We are grateful to the Canadian Natural Sciences and Engineering Research Council (RGPIN-2018-06748), the Canadian Foundation for Innovation (229288), the Canadian Institute for Advanced Research (BSE-BERL-162173), and Canada Research Chairs for financial support. This research was undertaken thanks in part to funding from the Canada First Research Excellence Fund, Quantum Materials and Future Technologies Program. We thank Ben Herring at the UBC Shared Instrument Facility for assistance with the GC-MS instrument and method development. We thank Dr. Monika Stolar for contributions to the development and editing of this manuscript. Finally, we thank the entire Berlinguette Group at the University of British Columbia for their continued support and collaboration in studying the membrane reactor.

1. Pd rolling
<ol>
	<li>Clean the Pd wafer bar with a mixture of hexanes using a cotton cloth. 
	CAUTION: Hexane is flammable, a health hazard, an irritant, and environmentally damaging. Work under proper ventilation (i.e., a snorkel or a fume hood).</li>
	<li>Roll the Pd wafer using a manual roller until reaching a thickness of &#8804;150 &#181;m, as determined by a digital micrometer.</li>
	<li>Roll the Pd using an automatic roller to a thickness of 25 &#181;m, as determined by a digital micrometer. Then, cut the resulting Pd into the desired dimensions (e.g., 3.5 cm x 3.5 cm).</li>
</ol>
2. Pd annealing
<ol>
	<li>Load the rolled Pd foils into a muffle oven with an N2 atmosphere.</li>
	<li>Heat the Pd foils starting at 25 &#176;C, and ramp the temperature to 850 &#176;C at a rate of 60 &#176;C/h. Hold the temperature at 850 &#176;C for 1.5 h, and then cool the oven to room temperature at a rate of 60 &#176;C/h.</li>
</ol>
3. Pd cleaning
<ol>
	<li>Prepare a cleaning solution by combining 10 mL of nitric acid, 20 mL of 30% (v/v) hydrogen peroxide, and 10 mL of deionized water. 
	CAUTION: Nitric acid is corrosive, an oxidant, and toxic. Hydrogen peroxide is corrosive, an oxidant, and harmful.</li>
	<li>Submerge the annealed Pd foils in the cleaning solution until the vigorous bubbling subsides or the solution turns yellow (20-30 min).</li>
	<li>Rinse the Pd foils twice with DI water and once with isopropyl alcohol, and then dry with air.</li>
</ol>
4. Reactor assembly (Figure 2, left to right)
<ol>
	<li>Assemble the reactor by sandwiching the Pd membrane between two halves of an electrochemical H-cell.</li>
	<li>Place a chemical-resistant gasket between the left-hand side of the cell and the Pd membrane.</li>
	<li>Place an additional chemical-resistant gasket between the Pd membrane and the right- hand side of the electrochemical cell.</li>
	<li>Seal the resulting cell configuration with a clip.</li>
</ol>
<img alt="Figure 2" class="xfigimg" src="/files/ftp_upload/65098/65098fig02v2.jpg" /> 
Figure 2: An image of the H-cell assembly.&#160;The electrochemical compartment contains 1 M H2SO4&#160;electrolyte; this is where water oxidation occurs. The palladium membrane separates the two halves of the H-cell, and the gaskets provide a leak-free seal. The hydrogenation compartment contains 0.01 M propiophenone in ethanol (EtOH).&#160;<a href="https://www.jove.com/files/ftp_upload/65098/65098fig02largev2.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
5. Pd electrodeposition
<ol>
	<li>Prepare an electroplating solution by dissolving PdCl2 into 1 M HCl to reach a concentration of 15.9 mM. 
	CAUTION: PdCl2 is harmful and corrosive. HCl is corrosive and an irritant.</li>
	<li>Assemble the reactor using a clean Pd foil from step 3.</li>
	<li>Fill the electrochemical compartment of the reactor with 24 mL of the prepared electroplating solution, and leave the hydrogenation compartment empty.</li>
	<li>Place a Pt mesh anode and an Ag/AgCl reference electrode into the solution in the electrochemical compartment.</li>
	<li>Connect the electrodes to a potentiostat, and apply a potential of -0.2 V versus Ag/AgCl to the Pd foil until a charge of 15 C has passed.</li>
	<li>Disassemble the reactor, rinse the resulting Pd membrane twice with deionized water and once with isopropyl alcohol, and then dry the membrane under a stream of air or N2. The Pd membrane will now have a visible deposition of Pd black on the surface that was exposed to the electroplating solution.</li>
</ol>
6. Atm-MS reactor setup
<ol>
	<li>Assemble the reactor as indicated in step 4. Fill the electrochemical compartment with 1 M H2SO4, and fill the hydrogenation compartment with ethanol. Do not add hydrogenation feedstock. 
	CAUTION: H2SO4 is harmful and corrosive. Ethanol is flammable, harmful, and a health hazard.</li>
	<li>Submerge a Pt counter electrode in the electrolyte. Connect the Pt counter electrode and the Pd membrane to a power supply using alligator clips. Connect the Pt counter electrode as the positive electrode and the Pd membrane as the negative electrode.</li>
	<li>Apply a constant current of 25 mA.</li>
</ol>
7. Atm-MS instrument setup
<ol>
	<li>Turn on the power switch on the back of the atm-MS unit, just below the power cord.</li>
	<li>Press the pump button on the front to turn on the pump (it will light up blue when on). Then, turn on the bake jacket (green round switch, the light will come on).</li>
	<li>Turn on the capillary channel to be used (red round switches next to the channels, the light will come on). Check that the channel used is turned on by feeling the tube being heated. 
	NOTE: The green LED next to &#34;vac ok&#34; will come on within a few minutes of turning the pump on. To turn off the system after finishing the experiments, turn off all the switches that have been turned on.</li>
	<li>Connect the hydrogenation cell outlet to the atm-MS capillaries. This connection must be airtight.</li>
</ol>
8. Atm-MS software setup
<ol>
	<li>Click on the Service desktop shortcut. Go to Setup | SEM/Emission Control, and check the boxes for both SEM and emissions. Press OK. Close the service window.</li>
	<li>Click on the Measure shortcut, and go to Sequence | Execute.</li>
	<li>Fill in the following parameters: Measurements = 30, Purge time = 30 s. Press File Manager, and create a folder to save the output data in. These settings will take 30 measurements with a purge time of 30 s between each measurement set; this can be changed if needed.</li>
	<li>The MID measurements file will then open. Select File Management, and open a program to measure the mass spectrometry signal for m/z = 2. This signal corresponds to the ionic current from H2+, the ionized form of hydrogen gas.</li>
	<li>Press OK to start the program. Do not close the measurement window as this will stop the instrument running.</li>
	<li>After the signal has stabilized (1-3 h), disconnect the atm-MS capillary from the hydrogenation compartment, and connect it to the electrochemical compartment.</li>
	<li>Save the data, and terminate the experiment when the signal for the electrochemical compartment has stabilized (about 30 min).</li>
	<li>Calculate the percentage of hydrogen permeation through the Pd membrane using Equation 1.</li>
</ol>
9. Electrochemical hydrogenation
<ol>
	<li>Assemble the reactor according to step 4.</li>
	<li>Fill the electrochemical compartment with 24 mL of 1 M H2SO4.</li>
	<li>Insert a Pt counter electrode into the electrochemical compartment through the counter electrode opening. Connect the Pt counter electrode to the positive terminal of a power supply, and connect the Pd membrane to the negative terminal via Cu tape.</li>
	<li>Apply a galvanostatic current of 25 mA (corresponds to 40 mA/cm2) across the cell for 15 min. The voltage will read between 3 V and 5 V.</li>
	<li>After 15 min has passed, fill the chemical compartment with 24 mL of reaction solution (e.g., 0.01 M propiophenone in ethanol). Maintain the galvanostatic current during reactant addition. 
	NOTE: Sample the initial reaction solution before it is added to the reactor. See step 9.6. 
	CAUTION: Propiophenone is harmful.</li>
	<li>Sample the chemical compartment periodically (e.g., every 15 min) by taking 30 &#181;L of reaction solution from the chemical compartment using a micropipette and dissolving the sample in 1 mL of dichloromethane. Store the samples in GC-MS vials until the reaction is complete. 
	&#8203;CAUTION: Dichloromethane is harmful and a health hazard.</li>
</ol>
10. Gas chromatography-mass spectrometry
<ol>
	<li>Load the sample vials into the autosampling tray.</li>
	<li>Launch the GC-MS software by clicking on the green Masshunter icon.</li>
	<li>Click on Sequence | Edit Sequence to open the sequence editing window. Fill in the desired sample names, vial (position in the autosampling tray), method path, method file, data path, and data file into the chart. Set the sample type to &#34;sample&#34; and the dilution to 1, and ensure that the data file matches the sample name.</li>
	<li>Adjust the method by clicking on Method | Edit Entire Method.
	<ol>
		<li>Ensure both Method information and Instrument acquisition are checked. Click on OK. Add Method comments (if desired).</li>
		<li>Ensure Data Acquisition and Data analysis are checked. Leave every other field blank. Click on OK.</li>
		<li>Ensure that the sample inlet is set to GC and the injection source is set to GC ALS. Check the Use MS box. Ensure that the inlet location is set to Front and the MS is connected to Front. Click on OK.</li>
	</ol>
	</li>
	<li>Under the Inlet tab, ensure the heater temperature is set to 250 &#176;C. Set the pressure to 7.2 psi and the He flow to 23.1 mL/min.</li>
	<li>Under the Oven tab, set the initial temperature to 50 &#176;C, and hold for 1 min. Next, set the ramp rate to 25 &#176;C/min and the temperature to 200 &#176;C, and hold for 0 min. Click on OK.</li>
	<li>Ensure none of the display signals are checked. Click on OK.</li>
	<li>Set the solvent delay to 2.50 min. Click on OK.</li>
	<li>Ensure that the selected monitors include the following: GC oven temperature, GC inlet F temperature, GC inlet F pressure, GC column 2 flow calc, MS EM volts, MS MS source, MS MS quad. Click on OK.</li>
	<li>Save the method under the desired method name.</li>
	<li>Start the sequence by clicking on Sequence | Start Sequence | Run Sequence.</li>
	<li>When the sequence is complete, view the data by opening the Masshunter software and clicking on the file name that was programmed in step 10.3.</li>
	<li>Identify the product peaks by clicking on Spectrum | Library search report to compare the acquired mass spectra to the NIST database.</li>
	<li>Calculate the relative composition of starting materials and products by using Equation 2. 
	<img alt="Equation 2" src="/files/ftp_upload/65098/65098eq02v2.jpg" style="margin: auto;" />&#160; (Eq. 2) 
	where A is the chemical component of interest, and n is the number of components measured by GC-MS. An example is as follows: 
	<img alt="Equation 3" src="/files/ftp_upload/65098/65098eq3v2.jpg" style="margin: auto;" /></li>
</ol>

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Patent applications based on the technology described in this work have been filed and published: Berlinguette, C. P.; Sherbo, R. S. "Methods and Apparatus for Performing Chemical and Electrochemical Reactions" US Patent Application No. 16964944 (PCT filed January 2019, national entry July 2020), Publication No. US20210040017A1 (published February 2021). Canadian Patent Application No. 3089508 (PCT filed January 2019, national entry July 2020), Publication No. CA3089508 (published August 2019). Priority data: US Provisional Patent Application No. 62/622,305 (filed January 2018).

The Pd membrane enables hydrogen permeation and chemical hydrogenation. The preparation of this membrane is, therefore, important to the efficacy of the membrane reactor. The Pd membrane size, crystallography, and surface are tuned to improve the experimental results. Although Pd metal can evolve hydrogen at any thickness, the Pd membranes are rolled to 25 &#181;m. This standardization of membrane thickness ensures that the time it takes for hydrogen to permeate through the membrane is constant for all the experiments. M...

Thermochemical hydrogenation reactions are used in ~20% of all chemical synthesis1. These reactions require large quantities of H2 gas, which are usually derived from fossil fuels, temperatures between 150 &#176;C and 600 &#176;C, and pressures up to 200 atm2. Electrochemical hydrogenation is an appealing way to bypass these requirements and to drive hydrogenation reactions using water and renewable electricity3. For conventional electrochemical hydrogenation, an unsaturated feedstock is dissolved in a protic electrolyte in an electrochemical cell. When a potential is applied to the cell, water oxidation occurs at the anode, while hydrogenation occurs&#160;at the cathode. In this reaction setup, both electrochemical water oxidation and chemical hydrogenation occur in the same reaction environment. The organic substrate is dissolved in a protic electrolyte to enable both electrochemical water splitting and hydrogenation of the feedstock. The proximity of these reactions can lead to byproduct formation and electrode fouling when the reactant is susceptible to nucleophilic attack or if the reactant concentration is too high (&#62;0.25 M)4.
These challenges prompted our group to explore alternative ways to electrochemically drive hydrogenation reactions5,6,7. This search resulted in the use of a Pd membrane, which is conventionally used in hydrogen gas separation8. We use it as an electrode for water electrolysis on the electrochemical reactor side. This novel application of a palladium membrane enables the physical separation of the site of electrochemical water oxidation from the site of chemical hydrogenation. The resulting reactor configuration has two compartments: 1) an electrochemical compartment for hydrogen production; and 2) a chemical compartment for hydrogenation (Figure 1). Protons are generated in the electrochemical compartment by applying a potential across the Pt anode and the Pd membrane, which also serves as the cathode. These protons then migrate to the Pd membrane, where they are reduced to surface-adsorbed hydrogen atoms. The electrochemical compartment can be subdivided to include an optional cation exchange membrane to facilitate this proton migration. The surface-adsorbed hydrogen atoms permeate through the interstitial octahedral sites of the Pd fcc lattice9 and emerge on the opposite face of the membrane in the hydrogenation compartment, where they react with the unsaturated bonds of a given feedstock to form hydrogenated products7,10,11,12,13,14,15,16. The Pd in the membrane reactor, therefore, acts as (i) a hydrogen-selective membrane, (ii) a cathode, and (iii) a catalyst for hydrogenation.
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/65098/65098fig1v2.jpg" /> 
Figure 1: Hydrogenation in a membrane reactor. Water oxidation at the anode produces protons, which are reduced on the palladium cathode. H permeates through the Pd membrane and reacts with propiophenone to form propylbenzene. Hydrogen evolution is a competing reaction that can occur on either side of the palladium membrane. For atmospheric mass-spectrometry, no chemical feedstock is used, necessitating H to leave the reactor in the form of H2 gas in either the electrochemical or hydrogenation compartments. <a href="https://www.jove.com/files/ftp_upload/65098/65098fig1largev2.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
The membrane reactor is assembled by sandwiching a Pd membrane between the anode and cathode compartments of an electrochemical H-cell12. Chemical-resistant O-rings are used to secure the membrane into place and ensure a leak-free seal. The electrochemical compartment of the membrane reactor contains a hydrogen-rich aqueous solution. In this study, we use 1 M H2SO4 and an anode that consists of a Pt wire enveloped in a 5 cm2 piece of platinum mesh. The anode is submerged in the electrolyte solution through a hole in the top of the electrochemical compartment. The chemical hydrogenation compartment contains a solvent and hydrogenation feedstock7,10,11,12,16,17. The hole at the top of the H-cell compartment is used for sampling. The experiments shown here use 0.01 M propiophenone in ethanol as the hydrogenation feed. However, the starting material (and concentration) can be varied to fit the experimental needs. For instance, a starting material that contains a long hydrocarbon chain and an alkyne functional group may be dissolved in pentane to improve solubility11. The applied current for the reaction can be between 5 mA/cm2 and 300 mA/cm2. All reactions are carried out under ambient temperature and pressure.
Atmospheric mass spectrometry (atm-MS) is used to measure the percent of hydrogen in the electrochemical compartment that permeates to the hydrogenation compartment11,12.&#160;This measurement is important to understand&#160;the energy inputs required for the membrane reactor, because it reveals the maximum possible hydrogen utilization (i.e., how much of the hydrogen being produced can actually be used for hydrogenation reactions). Hydrogen permeation through the Pd membrane is calculated by measuring the amount of H2 that evolves from both the electrochemical and hydrogenation compartments11,12. A permeation value of 100% means that all the hydrogen produced in the electrochemical compartment is transported through the Pd membrane to the hydrogenation compartment and then subsequently combines to form hydrogen gas. A permeation value of &#60;100% means&#160;that hydrogen evolution occurs in the electrochemical compartment prior to permeating through the membrane. As H2 is produced from either the electrochemical or hydrogenation compartment, it enters the instrument and is ionized to H2+. The quadrupole selects fragments of m/z = +2, and the corresponding charge is measured by the detector. The plot obtained by this technique is the ionic charge over time. The ionic charge is measured for the hydrogenation compartment first, and when the signal stabilizes, the channels are changed to measure the electrochemical compartment. Hydrogen permeation is calculated by dividing the average ionic charge in the hydrogenation compartment by the total ionic charge measured in the reactor (Equation 1)11,12. To calculate hydrogen permeation, H2 from the hydrogenation and electrochemical compartments are measured separately using atm-MS.
<img alt="Equation 1" src="/files/ftp_upload/65098/65098eq1v2.jpg" style="margin: auto;" /> (Eq. 1)
Gas chromatography mass spectrometry (GC-MS) is used to monitor the progress of the hydrogenation reaction12,14,15,16. To collect data for the example, the hydrogenation compartment of the reactor is filled with 0.01 M propiophenone in ethanol. By applying a potential across the Pt anode and the Pd cathode, reactive hydrogen is supplied to the hydrogenation compartment. The reactive hydrogen atoms then hydrogenate the unsaturated feedstock, and the products are quantified using GC-MS, where the sample is fragmented and ionized. By analyzing the mass of these fragments, the composition of the hydrogenation solution can be determined, and reaction rates can be calculated12,14,15,16.

<table><tbody><tr><td>Ag/AgCl Reference Electrode</td><td>BASi research products</td><td>MW-2021</td><td>Reference electrode</td></tr><tr><td>Analytical Balance</td><td>Cole-Parmer</td><td>RK-11219-03</td><td>Instrument</td></tr><tr><td>Atmospheric Mass Spectrometer</td><td>ESS CatalySys</td><td>NA</td><td>Instrument</td></tr><tr><td>Bench Power Supply</td><td>Newark</td><td>1550</td><td>Instrument</td></tr><tr><td>Conductive Copper Foil Electrical Tape&amp;nbsp;</td><td>McMaster Carr</td><td>76555A711</td><td>Electrochemical cell assembly</td></tr><tr><td>Dichloromethane</td><td>Sigma Aldrich</td><td>270997</td><td>Reagent</td></tr><tr><td>Electric Rolling Press with Dual Micrometer</td><td>MTI Corporation</td><td>MR100A</td><td>Equipment</td></tr><tr><td>Electrochemical glass H-cell</td><td>University of British Columbia glass blowing</td><td>NA</td><td>Electrochemical cell assembly</td></tr><tr><td>ESS catalysis QUADSTAR</td><td>ESS CatalySys</td><td>NA</td><td>Software</td></tr><tr><td>Ethanol</td><td>Sigma Aldrich</td><td>493511</td><td>Reagent</td></tr><tr><td>Flat Rolling Mill</td><td>Pepetolls</td><td>18700A</td><td>Equipment</td></tr><tr><td>Gas Chromatography Mass Spectrometer</td><td>Agilent</td><td>NA</td><td>Instrument</td></tr><tr><td>GC-MS vial</td><td>Agilent</td><td>5067-0205</td><td>Vial for GC-MS</td></tr><tr><td>Hexanes</td><td>Sigma Aldrich</td><td>1.0706</td><td>Reagent</td></tr><tr><td>Hydrochloric Acid</td><td>Sigma Aldrich</td><td>258148</td><td>Reagent</td></tr><tr><td>Hydrogen peroxide solution (30% v/v)</td><td>Sigma Aldrich</td><td>H1009</td><td>Reagent</td></tr><tr><td>Isopropyl Alcohol</td><td>Sigma Aldrich</td><td>W292907</td><td>Reagent</td></tr><tr><td>Masshunter Aquisition Software</td><td>Agilent</td><td>G1617FA</td><td>Software</td></tr><tr><td>Micropipette (100 &amp;micro;L - 1000 &amp;micro;L)</td><td>Gilson</td><td>F123602</td><td>instrument</td></tr><tr><td>Micropipette (20 &amp;micro;L - 200 &amp;micro;L)&amp;nbsp;</td><td>Gilson</td><td>F123601</td><td>Instrument</td></tr><tr><td>Mitutoyo Digital Micrometer</td><td>Uline</td><td>H-2780</td><td>Instrument</td></tr><tr><td>Muffle Furnace</td><td>MTI Corporation</td><td>KSL-1100X</td><td>Equipment</td></tr><tr><td>Nitric acid</td><td>Sigma Aldrich</td><td>438073</td><td>Reagent</td></tr><tr><td>Nitrogen gas</td><td>Sigma Aldrich</td><td>608661</td><td>Reagent</td></tr><tr><td>Palladium (II) Chloride</td><td>Sigma Aldrich</td><td>520659</td><td>Reagent</td></tr><tr><td>Pd wafer bar, 1 oz, 99.95%</td><td>Silver Gold Bull.</td><td>NA</td><td>Reagent</td></tr><tr><td>Platinum Auxiliary Electrode</td><td>BASi research products</td><td>MW-1032</td><td>Anode</td></tr><tr><td>Potentiostat</td><td>Metrohm</td><td>PGSTAT302N</td><td>Instrument</td></tr><tr><td>Propiophenone</td><td>Sigma Aldrich</td><td>P51605</td><td>Reagent</td></tr><tr><td>Proton Exchange Membrane, Nafion 212</td><td>Fuel cell store&amp;nbsp;</td><td>NA</td><td>Electrochemical cell assembly</td></tr><tr><td>Sulfuric acid&amp;nbsp;</td><td>Sigma Aldrich</td><td>258105</td><td>Reagent</td></tr></tbody></table>

hydrogen production and utilization in a membrane reactor

Industrial hydrogenation consumes ~11 Mt of fossil-derived H2 gas yearly. Our group invented a membrane reactor to bypass the need to use H2 gas for hydrogenation chemistry. The membrane reactor sources hydrogen from water and drives reactions using renewable electricity. In this reactor, a thin piece of Pd separates an electrochemical hydrogen production compartment from a chemical hydrogenation compartment. The Pd in the membrane reactor acts as (i) a hydrogen-selective membrane, (ii) a cathode, and (iii) a catalyst for hydrogenation. Herein, we report the use of atmospheric mass spectrometry (atm-MS) and gas chromatography mass spectrometry (GC-MS) to demonstrate that an applied electrochemical bias across a Pd membrane enables efficient hydrogenation without direct H2 input in a membrane reactor. With atm-MS, we measured a hydrogen permeation of 73%, which enabled the hydrogenation of propiophenone to propylbenzene with 100% selectivity, as measured by GC-MS. In contrast to conventional electrochemical hydrogenation, which is limited to low concentrations of starting material dissolved in a protic electrolyte, the physical separation of hydrogen production from utilization in the membrane reactor enables hydrogenation in any solvent or at any concentration. The use of high concentrations and a wide range of solvents is particularly important for reactor scalability and future commercialization.

Atm-MS is used to measure the ionic current of the hydrogen that is produced in the membrane reactor. We can use these measurements to quantify how much hydrogen permeates through the Pd membrane during electrolysis. First, the hydrogen evolving from the hydrogenation compartment is measured (Figure 3, left of the dotted lines). When the signal reaches a steady state, the channel is switched to the electrochemical compartment. The H2 gas evolving from the electrochemical compartme...

Watch this Scientific Journal Video about Hydrogen Production and Utilization in a Membrane Reactor at JoVE.com

Hydrogen Production and Utilization in a Membrane Reactor

Membrane reactors enable hydrogenation in ambient conditions without direct H2 input. We can track the hydrogen production and utilization in these systems using atmospheric mass spectrometry (atm-MS) and gas chromatography mass spectrometry (GC-MS).

Industrial hydrogenation consumes ~11 Mt of fossil-derived H2 gas yearly. Our group invented a membrane reactor to bypass the need to use H2 gas for ...

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Chemistry

2.2K Views.  The University of British Columbia. Membrane reactors enable hydrogenation in ambient conditions without direct H2 input. We can track the hydrogen production and utilization in these systems using atmospheric mass spectrometry (atm-MS) and gas chromatography mass spectrometry (GC-MS).

Video: Hydrogen Production and Utilization in a Membrane Reactor

Untargeted Metabolomics from Biological Sources Using Ultraperformance Liquid Chromatography-High Resolution Mass Spectrometry (UPLC-HRMS)

Here we present a workflow to analyze the metabolic profiles for biological samples of interest including; cells, serum, or tissue. The sample is first separated into polar and non-polar fractions by a liquid-liquid phase extraction, and partially purified to facilitate downstream analysis. Both aqueous (polar metabolites) and organic (non-polar metabolites) phases of the initial extraction are processed to survey a broad range of metabolites. Metabolites are separated by different liquid chromatography methods based upon their partition properties. In this method, we present microflow ultra-performance (UP)LC methods, but the protocol is scalable to higher flows and lower pressures. Introduction into the mass spectrometer can be through either general or compound optimized source conditions. Detection of a broad range of ions is carried out in full scan mode in both positive and negative mode over a broad m/z range using high resolution on a recently calibrated instrument. Label-free differential analysis is carried out on bioinformatics platforms. Applications of this approach include metabolic pathway screening, biomarker discovery, and drug development.

Untargeted Metabolomics from Biological Sources Using Ultraperformance Liquid Chromatography-High Resolution Mass Spectrometry UPLC-HRMS

Untargeted metabolomics provides a hypothesis generating snapshot of a metabolic profile. This protocol will demonstrate the extraction and analysis of metabolites from cells, serum, or tissue. A range of metabolites are surveyed using liquid-liquid phase extraction, microflow ultraperformance liquid chromatography/high-resolution mass spectrometry (UPLC-HRMS) coupled to differential analysis software.

Here we present a workflow to analyze the metabolic profiles for biological samples of interest including; cells, serum, or tissue. The sample is first ...

A Simple, Low-cost, and Robust System to Measure the Volume of Hydrogen Evolved by Chemical Reactions with Aqueous Solutions

There is a growing research interest in the development of portable systems which can deliver hydrogen on-demand to proton exchange membrane (PEM) hydrogen fuel cells. Researchers seeking to develop such systems require a method of measuring the generated hydrogen. Herein, we describe a simple, low-cost, and robust method to measure the hydrogen generated from the reaction of solids with aqueous solutions. The reactions are conducted in a conventional one-necked round-bottomed flask placed in a temperature controlled water bath. The hydrogen generated from the reaction in the flask is channeled through tubing into a water-filled inverted measuring cylinder. The water displaced from the measuring cylinder by the incoming gas is diverted into a beaker on a balance. The balance is connected to a computer, and the change in the mass reading of the balance over time is recorded using data collection and spreadsheet software programs. The data can then be approximately corrected for water vapor using the method described herein, and parameters such as the total hydrogen yield, the hydrogen generation rate, and the induction period can also be deduced. The size of the measuring cylinder and the resolution of the balance can be changed to adapt the setup to different hydrogen volumes and flow rates.

The study of methods to generate on-demand hydrogen for fuel cells continues to grow in importance. However, systems to measure hydrogen evolution from the reaction of chemicals with water can be complicated and expensive. This article details a simple, low-cost, and robust method to measure the evolution of hydrogen gas.

There is a growing research interest in the development of portable systems which can deliver hydrogen on-demand to proton exchange membrane (PEM) ...

Experimental Methods for Efficient Solar Hydrogen Production in Microgravity Environment

Long-term space flights and cis-lunar research platforms require a sustainable and light life-support hardware which can be reliably employed outside the Earth's atmosphere. So-called 'solar fuel' devices, currently developed for terrestrial applications in the quest for realizing a sustainable energy economy on Earth, provide promising alternative systems to existing air-revitalization units employed on the International Space Station (ISS) through photoelectrochemical water-splitting and hydrogen production. One obstacle for water (photo-) electrolysis in reduced gravity environments is the absence of buoyancy and the consequential, hindered gas bubble release from the electrode surface. This causes the formation of gas bubble froth layers in proximity to the electrode surface, leading to an increase in ohmic resistance and cell-efficiency loss due to reduced mass transfer of substrates and products to and from the electrode. Recently, we have demonstrated efficient solar hydrogen production in microgravity environment, using an integrated semiconductor-electrocatalyst system with p-type indium phosphide as the light-absorber and a rhodium electrocatalyst. By nanostructuring the electrocatalyst using shadow nanosphere lithography and thereby creating catalytic 'hot spots' on the photoelectrode surface, we could overcome gas bubble coalescence and mass transfer limitations and demonstrated efficient hydrogen production at high current densities in reduced gravitation. Here, the experimental details are described for the preparations of these nanostructured devices and further on, the procedure for their testing in microgravity environment, realized at the Bremen Drop Tower during 9.3 s of free fall.

Efficient solar-hydrogen production has recently been realized on functionalized semiconductor-electrocatalyst systems in a photoelectrochemical half-cell in microgravity environment at the Bremen Drop Tower. Here, we report the experimental procedures for manufacturing the semiconductor-electrocatalyst device, details of the experimental set-up in the drop capsule and the experimental sequence during free fall.

Long-term space flights and cis-lunar research platforms require a sustainable and light life-support hardware which can be reliably employed outside the ...

Developing Photosensitizer-Cobaloxime Hybrids for Solar-Driven H2 Production in Aqueous Aerobic Conditions

Developing photocatalytic H2 production devices is the one of the key steps for constructing a global H2-based renewable energy infrastructure. A number of photoactive assemblies have emerged where a photosensitizer and cobaloxime-based H2 production catalysts work in tandem to convert light energy into the H-H chemical bonds. However, the long-term instability of these assemblies and the need for hazardous proton sources have limited their usage. Here, in this work, we have integrated a stilbene-based organic dye into the periphery of a cobaloxime core via a distinct axial pyridine linkage. This strategy allowed us to develop a photosensitizer-catalyst hybrid structure with the same molecular framework. In this article, we have explained the detailed procedure of the synthesis of this hybrid molecule in addition to its comprehensive chemical characterization. The structural and optical studies have exhibited an intense electronic interaction between the cobaloxime core and the organic photosensitizer. The cobaloxime was active for H2 production even in the presence of water as the proton source. Here, we have developed a simple airtight system connected with an online H2 detector for the investigation of the photocatalytic activity by this hybrid complex. This photosensitizer-catalyst dyad present in the experimental setup continuously produced H2 once it was exposed in the natural sunlight. This photocatalytic H2 production by the hybrid complex was observed in aqueous/organic mixture media in the presence of a sacrificial electron donor under complete aerobic conditions. Thus, this photocatalysis measurement system along with the photosensitizer-catalyst dyad provide valuable insight for the development of next generation photocatalytic H2 production devices.

Developing Photosensitizer-Cobaloxime Hybrids for Solar-Driven H2 Production in Aqueous Aerobic Conditions

We have directly incorporated a stilbene-based organic dye into a cobaloxime core to generate a photosensitizer-catalyst dyad for photocatalytic H2 production. We have also developed a simple experimental setup for evaluating the light-driven H2 production by photocatalytic assemblies.

Developing photocatalytic H2 production devices is the one of the key steps for constructing a global H2-based renewable energy infrastructure. A number ...

Ion-Exchange Membranes for the Fabrication of Reverse Electrodialysis Device

Reverse electrodialysis (RED) is an effective way to generate power by mixing two different salt concentrations in water using cation-exchange membranes (CEM) and anion-exchange membranes (AEM). The RED stack is composed of an alternating arrangement of the cation-exchange membrane and anion-exchange membrane. The RED device acts as a potential candidate for fulfilling the universal demand for future energy crises. Here, in this article, we demonstrate a procedure to fabricate a reverse electrodialysis device using laboratory-scale CEM and AEM for power production. The active area of the ion-exchange membrane is 49 cm2. In this article, we provide a step-by-step procedure for synthesizing the membrane, followed by the stack&#39;s assembly and power measurement. The measurement conditions and net power output calculation have also been explained. Furthermore, we describe the fundamental parameters that are taken into consideration for obtaining a reliable outcome. We also provide a theoretical parameter that affects the overall cell performance relating to the membrane and the feed solution. In short, this experiment describes how to assemble and measure RED cells on the same platform. It also contains the working principle and calculation used for estimating the net power output of the RED stack using CEM and AEM membranes.

We demonstrate the fabrication of a reverse electrodialysis device using a cation-exchange membrane (CEM) and anion-exchange membrane (AEM) for power generation.

Reverse electrodialysis (RED) is an effective way to generate power by mixing two different salt concentrations in water using cation-exchange membranes ...

Engineering

Synthesis of Metal Nanoparticles Supported on Carbon Nanotube with Doped Co and N Atoms and its Catalytic Applications in Hydrogen Production

A method for facile synthesis of nanostructured catalysts supported on carbon nanotubes with atomically dispersed cobalt and nitrogen dopant is presented herein. The novel strategy is based on a facile one-pot pyrolysis treatment of cobalt (II) acetylacetonate and nitrogen-rich organic precursors under Ar atmosphere at 800 &#176;C, resulting in the formation of Co- and N- co-doped carbon nanotube with earthworm-like morphology. The obtained catalyst was found to have a high density of defect sites, as confirmed by Raman spectroscopy. Here, cobalt (II) nanoparticles were stabilized on the atomically dispersed cobalt- and nitrogen-doped carbon nanotubes. The catalyst was confirmed to be effective in the catalytic hydrolysis of ammonia borane, in which the turnover frequency was 5.87 mol H2&#183;molCo-1&#183;min-1, and the specific hydrogen generation rate was determined to be 2447 mL H2&#183;gCo-1&#183;min-1. A synergistic function between the Co nanoparticle and the doped carbon nanotubes was proposed for the first time in the catalytic hydrolysis of ammonia borane reaction under a mild condition. The resulting hydrogen production with its high energy density and minimal refueling time could be suitable for future development as energy sources for mobile and stationary applications such as road trucks and forklifts in transport and logistics.

Here, we present a protocol to synthesize Co nanoparticles supported on carbon nanotubes with Co- and N- dopants for hydrogen productions.

A method for facile synthesis of nanostructured catalysts supported on carbon nanotubes with atomically dispersed cobalt and nitrogen dopant is presented ...

Exploring Innovative 3D Electrodes for Hydrogen Peroxide Fuel Cells

Membraneless Hydrogen Peroxide Fuel Cells as a Promising Clean Energy Source

In an in-depth investigation of membraneless hydrogen peroxide-based fuel cells (H2O2 FCs), hydrogen peroxide (H2O2), a carbon-neutral compound, is demonstrated to undergo electrochemical decomposition to produce H2O, O2, and electrical energy. The unique redox properties of H2O2 position it as a viable candidate for sustainable energy applications. The proposed membraneless design addresses the limitations of conventional fuel cells, including fabrication complexities and design challenges. A novel three-dimensional electrode, synthesized via electroplating techniques, is introduced. Constructed from Au-electroplated carbon fiber cloth combined with Ni-foam, this electrode showcases enhanced electrochemical reaction kinetics, leading to an increased power density for H2O2 FCs. The performance of fuel cells is intricately linked to the pH levels of the electrolyte solution. Beyond FC applications, such electrodes hold potential in portable energy systems and as high surface area catalysts. This study emphasizes the significance of electrode engineering in optimizing the potential of H2O2 as an environmentally friendly energy source.

Author Spotlight: Design and Evaluation of Au-Electroplated Carbon Fiber Cloth Electrodes for Hydrogen Peroxide Fuel Cells 

This protocol introduces the design and evaluation of innovative three-dimensional electrodes for hydrogen peroxide fuel cells, utilizing Au-electroplated carbon fiber cloth and Ni-foam electrodes. The research findings highlight hydrogen peroxide's potential as a promising candidate for sustainable energy technologies.

In an in-depth investigation of membraneless hydrogen peroxide-based fuel cells (H2O2 FCs), hydrogen peroxide (H2O2), a carbon-neutral compound, is ...

Proton Exchange Membrane Fuel Cells

Source: Laboratories of Margaret Workman and Kimberly Frye - Depaul University
The United States consumes a large amount of energy &#8211; the current rate is around 97.5 quadrillion BTUs annually. The vast majority (90%) of this energy comes from non-renewable fuel sources. This energy is used for electricity (39%), transportation (28%), industry (22%), and residential/commercial use (11%). As the world has a limited supply of these non-renewable sources, the United States (among others) is expanding the use of renewable energy sources to meet future energy needs. One of these sources is hydrogen.
Hydrogen is considered a potential renewable fuel source, because it meets many important criteria: it&#8217;s available domestically, it has few harmful pollutants, it&#8217;s energy efficient, and it&#8217;s easy to harness. While hydrogen is the most abundant element in the universe, it is only found in compound form on Earth. For example, it is combined with oxygen in water as H2O. To be useful as a fuel, it needs to be in the form of H2 gas. Therefore, if hydrogen is to be used as a fuel for cars or other electronics, H2 needs to be made first. Thusly, hydrogen is often called an &#8220;energy carrier&#8221; rather than a &#8220;fuel.&#8221;
Currently, the most popular way to make H2 gas is from fossil fuels, through steam reforming of hydrocarbons or coal gasification. This does not reduce dependence on fossil fuels and is energy intensive. A less-used method is by electrolysis of water. This also requires an energy source, but it can be a renewable source, like wind or solar power. In electrolysis, water (H2O) is split into its component parts, hydrogen gas (H2) and oxygen gas (O2), through an electrochemical reaction. The hydrogen gas made through the process of electrolysis can then be used in a Proton Exchange Membrane (PEM) fuel cell, generating an electric current. This electric current can be used to power motors, lights, and other electrical devices.

Source: Laboratories of Margaret Workman and Kimberly Frye - Depaul University
The United States consumes a large amount of energy &#8211; the current ...

Education

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Environmental Sciences

Environmental Science

Hydrogenation

Source: Vy M. Dong and Zhiwei Chen, Department of Chemistry, University of California, Irvine, CA
This experiment will demonstrate the hydrogenation of chalcone as an example of an alkene hydrogenation reaction (Figure 1). In this experiment, palladium on carbon (Pd/C) will be used as a heterogeneous catalyst for the process. A balloon will be used to supply the hydrogen atmosphere.
<img alt="Figure 1" src="/files/ftp_upload/10350/10350fig1.jpg" /> 
Figure 1: Diagram showing the hydrogenation of chalcone to 3-phenylpropiophenone.

Catalytic Hydrogenation of Alkene: Applications in Chemistry

Source: Vy M. Dong and Zhiwei Chen, Department of Chemistry, University of California, Irvine, CA
This experiment will demonstrate the hydrogenation of ...

Organic Chemistry II

Catalytic Reactor: Hydrogenation of Ethylene

Source: <a href="https://www.jove.com/author/Kerry+M._Dooley">Kerry M. Dooley</a> and Michael G. Benton, Department of Chemical Engineering, Louisiana State University, Baton Rouge, LA
The hydrogenation of ethylene (C2H4) to ethane (C2H6) has often been studied as a model reduction reaction in characterizing new metal catalysts.1-2 While supported nickel is not the most active metal catalyst for this reaction, it is active enough that reaction can take place at &#60; 200&#176;C.
The reaction typically involves adsorbed, dissociated hydrogen (H2) reacting with adsorbed ethylene. In other words, both hydrogen-atoms and ethylene molecules form bonds with a metal site (here denoted &#34;S&#34;). The strong bonding of ethylene with S weakens the double bond sufficiently to allow hydrogen atoms to add to ethylene, forming ethane, which is not adsorbed.
The purpose of this experiment is, first, to convert raw composition measurements to limiting reactant fractional conversions.3 These conversions can then be used in a plug-flow reactor (PFR) to fit the data to a standard power-law kinetics model by the &#34;Integral Method&#34;.3 A comparison of the experimental orders of reaction for both ethylene and hydrogen with the theoretical orders reveals in this case that the reaction is kinetically controlled rather than mass-transfer controlled.

Heterogeneous Catalytic Reactor and Hydrogenation of Ethylene

Source: Kerry M. Dooley and Michael G. Benton, Department of Chemical Engineering, Louisiana State University, Baton Rouge, LA
The hydrogenation of ...