This work is supported by the Natural Science Foundation of China (No. 21506194, 21676255).

Caution: Please consult all relevant Material Safety Data Sheets (MSDS) before operation. Several chemicals are flammable and highly corrosive. Concentrating light can cause harmful light intensity and temperature increases. Please use all appropriate safety devices such as personal protective equipment (safety glasses, gloves, lab coats, pants, etc.).
1. Catalyst Preparation
<ol>
	<li>Preparation of TiO2 by anodization 
	Note: Anodization uses metal...

<ol>
	<li>De-Richter, R. K., Ming, T., Caillol, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fighting+global+warming+by+photocatalytic+reduction+of+CO2,+using+giant+photocatalytic+reactors.">Fighting global warming by photocatalytic reduction of CO2, using giant photocatalytic reactors.</a> Renewable &amp; Sustainable Energy Reviews. 19 (1), 82-106 (2013).</li><li>Fang, Y., Wang, X. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Photocatalytic+CO2+conversion+by+polymeric+carbon+nitrides.">Photocatalytic CO2 conversion by polymeric carbon nitrides.</a> Chemical Communications. 54 (45), 5674-5687 (2018).</li><li>Kondratenko, E. 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K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Photocatalytic+Reduction+of+CO2+on+TiO2+and+Other+Semiconductors.">Photocatalytic Reduction of CO2 on TiO2 and Other Semiconductors.</a> Angewandte Chemie International Edition. 52 (29), 7372-7408 (2013).</li><li>Weinstein, L. A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Concentrating+Solar+Power.">Concentrating Solar Power.</a> Chemical Reviews. 115 (23), 12797-12838 (2015).</li><li>Herrmann, J. M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=TiO2+-based+solar+photocatalytic+detoxification+of+water+containing+organic+pollutants.+Case+studies+of+2,+4-dichlorophenoxyaceticacid+(2,+4+-+D)+and+of+benzofuran.">TiO2 -based solar photocatalytic detoxification of water containing organic pollutants. Case studies of 2, 4-dichlorophenoxyaceticacid (2, 4 - D) and of benzofuran.</a> Applied Catalysis B Environmental. 17 (1-2), 15-23 (1998).</li><li>Zeng, K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Combined+effects+of+initial+water+content+and+heating+parameters+on+solar+pyrolysis+of+beech+wood.">Combined effects of initial water content and heating parameters on solar pyrolysis of beech wood.</a> Energy. 125, 552-561 (2017).</li><li>Zeng, K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Characterization+of+solar+fuels+obtained+from+beech+wood+solar+pyrolysis.">Characterization of solar fuels obtained from beech wood solar pyrolysis.</a> Fuel. 188, 285-293 (2017).</li><li>Nguyen, T. V., Wu, J. C. S., Chiou, C. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Photoreduction+of+CO+over+Ruthenium+dye-sensitized+TiO-based+catalysts+under+concentrated+natural+sunlight.">Photoreduction of CO over Ruthenium dye-sensitized TiO-based catalysts under concentrated natural sunlight.</a> Catalysis Communications. 9 (10), 2073-2076 (2008).</li><li>Guan, G., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Photoreduction+of+carbon+dioxide+with+water+over+K2Ti6O13,+photocatalyst+combined+with+Cu/ZnO+catalyst+under+concentrated+sunlight.">Photoreduction of carbon dioxide with water over K2Ti6O13, photocatalyst combined with Cu/ZnO catalyst under concentrated sunlight.</a> Applied Catalysis A: General. 249 (1), 11-18 (2003).</li><li>Han, S., Chen, Y. F., Abanades, S., Zhang, Z. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Improving+photoreduction+of+CO2+with+water+to+CH4+in+a+novel+concentrated+solar+reactor.">Improving photoreduction of CO2 with water to CH4 in a novel concentrated solar reactor.</a> Journal of Energy Chemistry. 26 (4), 743-749 (2017).</li><li>Roy, S. C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Toward+solar+fuels:+photocatalytic+conversion+of+carbon+dioxide+to+hydrocarbons.">Toward solar fuels: photocatalytic conversion of carbon dioxide to hydrocarbons.</a> ACS Nano. 4 (3), 1259-1278 (2010).</li><li>Li, D., Chen, Y. F., Abanades, S., Zhang, Z. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Enhanced+activity+of+TiO2+by+concentrating+light+for+photoreduction+of+CO2+with+H2O+to+CH4.">Enhanced activity of TiO2 by concentrating light for photoreduction of CO2 with H2O to CH4.</a> Catalysis Communications. 113, 6-9 (2018).</li></ol>

Concentrating light reduces the light incident area and requires the use of a disc-shaped catalyst or a so-called fixed-bed reactor to hold the catalyst. Since the light source is usually a round-shaped lamp, the shape of the catalyst should also be round. To obtain a round disc, it is possible to press the powder into a disk by tableting or to change the metal foil into an oxide by anodization. The anodization method uses electricity to oxidize the metal to an oxide semiconductor. As the metal precursor is already a she...

The utilization of fossil fuels is accompanied by large amounts of CO2 emission, contributing greatly to global warming. CO2 capture, storage, and conversion are essential to reduce the CO2 content in the atmosphere1. The photoreduction of CO2 to hydrocarbons can reduce CO2, convert CO2 to fuels, and save solar energy. However, CO2 is an extremely stable molecule. Its C=O bond possesses a higher dissociation energy (about 750 kJ/mol)2. This means that CO2 is very hard to be activated and transformed, and only short wavelength lights with high energy can be functional during the process. Therefore, CO2 photoreduction studies suffer from low conversion efficiencies and reaction rates at present. Most reported CH4 yield rates are only at several &#181;mol&#183;gcata-1&#183;h-1 levels on a TiO2 catalyst3,4. The design and fabrication of photocatalytic systems with high conversion efficiency and reaction rate for CO2 reduction remain a challenge.
One popular area of research into CO2 photoreduction catalysts is to broaden the available light band to the visible spectrum and enhance the utilization efficiency of these wavelengths5,6. Instead, in this manuscript, we try to increase the reaction rate by enhancing the light intensity. As the driving force of a photocatalytic reaction is solar light, the basic idea is to use concentration technology to raise the incident solar light intensity and, therefore, increase the reaction rate. This is similar to a thermocatalytic process, where the reaction rate can be increased by increasing the temperature. Of course, the temperature effect cannot be not increased infinitely, and likewise with the light intensity; a major goal of this research is to find a suitable light intensity or concentration ratio.
This is not the first experiment that uses concentrating technology. In fact, it has been widely used in concentrating solar power and waste water treatment7,8. Biomaterials such as beech wood sawdust can be pyrolyzed in a solar reactor9,10. Some previous reports have mentioned the method for CO2 photoreduction11,12,13. One sample exhibited a 50% increment in the product yield when the light intensity was doubled14. Our group has found that concentrating light can raise CH4 yield rate with an up to 12-fold increase in intensity. In addition, pretreatment of catalyst before reaction by concentrating light can further increase the CH4 yield rate15. Here, we demonstrate the experimental system and method in detail.

<table>
	<tbody>
		<tr>
			<td>Ti foil, 99.99%</td>
			<td>Hebei Metal Technology Co., Ltd.</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Pt foil, 99.99%</td>
			<td>Tianjin Aida Henghao Technology Co., Ltd.</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Ammonium fluoride, 98%</td>
			<td>Aladdin</td>
			<td>A111758</td>
			<td>Humidity sensitive</td>
		</tr>
		<tr>
			<td>Glycol, &#62;99.9%</td>
			<td>Aladdin</td>
			<td>E103323</td>
			<td></td>
		</tr>
		<tr>
			<td>Anhydrous ethanol,&#62;99.9%</td>
			<td>Aladdin</td>
			<td>E111977</td>
			<td>Flammable</td>
		</tr>
		<tr>
			<td>Acetone, &#62;99.5%</td>
			<td>Hangzhou Shuanglin Chemical Co., Ltd.</td>
			<td>200-662-2</td>
			<td>Irritating smell</td>
		</tr>
		<tr>
			<td>Nitric acid, 65.0%-68.0%</td>
			<td>Hangzhou Shuanglin Chemical Co., Ltd.</td>
			<td>231-714-2</td>
			<td>Humidity sensitive</td>
		</tr>
		<tr>
			<td>Hydrogen peroxide, 30 wt. % in H2O</td>
			<td>Aladdin</td>
			<td>H112515</td>
			<td>Strong oxidative</td>
		</tr>
		<tr>
			<td>Urea, 99%</td>
			<td>Aladdin</td>
			<td>U111897</td>
			<td></td>
		</tr>
		<tr>
			<td>De-ionized water, 99.00%</td>
			<td>Laboratory made</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Xe lamp, CELHXF300/CELHXUV300</td>
			<td>Beijing Zhongjiao Jinyuan Co., Ltd.</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Stainless cylinder reactor, CEL-GPPC</td>
			<td>Beijing Zhongjiao Jinyuan Co., Ltd.</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Fresnel lens, MYlens</td>
			<td>Meiying Technology Co., Ltd.</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>7000 mesh sandpaper</td>
			<td>Zibo Taichuan Abrasives Co., Ltd.</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Ultrasonic cleaner, SK2210HP</td>
			<td>Shanghai Kedao Ultrasonic Instrument Co., Ltd.</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Thermostatical water bath, DF-101S</td>
			<td>Boncie Instrument Technology Co., Ltd.</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Alligator clip</td>
			<td>Guangzhou Rongyu Co., Ltd.</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>DC constant voltage source, DY-150V 2A</td>
			<td>Shanghai Anding Electric Co., Ltd.</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Muffle furnace, KSL-1200X</td>
			<td>Hefei Kejing Materials Technolgy Co., Ltd.</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Quartz glass</td>
			<td>Lianyungang Weida Quartz Products Co., Ltd.</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Thermocouples, WRNK-191K</td>
			<td>Feiyang Electric Accessories Co., Ltd.</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Electronmagnetic stirrer, 85-2</td>
			<td>Shanghai Zhiwei Electric Appliance Co., Ltd.</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Vacuum pump,SHB-IIIA</td>
			<td>Henan Province Taikang science and education equipment factory</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Gas Chromatograph, GC2014</td>
			<td>SHIMAPZU</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>HT-PLOT Q capillary column</td>
			<td>Hychrom</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Optical power meter,CEL-NP2000</td>
			<td>Beijing Zhongjiao Jinyuan Co., Ltd.</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Electronic scale, JJ124BC</td>
			<td>Shanghai Jingtian Electronic Instrument Co., Ltd.</td>
			<td></td>
			<td></td>
		</tr>
	</tbody>
</table>

co2 photoreduction to ch4 performance under concentrating solar light

We demonstrate a method for the enhancement of CO2 photoreduction. As the driving force of a photocatalytic reaction is from solar light, the basic idea is to use concentration technology to raise the incident solar light intensity. Concentrating a large-area light onto a small area cannot only increase light intensity, but also reduce the catalyst amount, as well as the reactor volume, and increase the surface temperature. The concentration of light can be realized by different devices. In this manuscript, it is realized by a Fresnel lens. The light penetrates the lens and is concentrated on a disc-shaped catalyst. The results show that both the reaction rate and the total yield are efficiently increased. The method can be applied to most CO2 photoreduction catalysts, as well as to similar reactions with a low reaction rate at natural light.

The original photocatalytic reactor system mainly contains two components, a Xe lamp and a stainless cylinder reactor. For the concentrating light reactor system, we added a Fresnel lens and a catalyst holder, as shown in Figure 1. The Fresnel lens is used to concentrate the light in a smaller area. As the light has been concentrated, the catalyst must be placed in a lit area; therefore, the catalyst is made into disc shape, and a holder is used to hold the c...

Watch this Scientific Journal Video about CO2 Photoreduction to CH4 Performance Under Concentrating Solar Light at JoVE.com

CO2 Photoreduction to CH4 Performance Under Concentrating Solar Light

We present a protocol for improving the performance of CO2 photoreduction to CH4 by heightening the incident light intensity via concentrating solar energy technology.

CO2 Photoreduction to CH4 Performance Under Concentrating Solar Light

We demonstrate a method for the enhancement of CO2 photoreduction. As the driving force of a photocatalytic reaction is from solar light, the basic idea ...

This method can help answer key questions in the artificial photosynthesis field, such as carbon dioxide photoreduction to methane. Concentrating technology can not only increase the light intensity but also reduce the catalyst amount as well as the reactor volume, while increasing the reaction temperature, thereby increasing the photoreduction reaction rate. Though this method can provide insight into photocatalytic reduction of carbon dioxide, it can also be applied to other systems such as concentrating solar power and wastewater treatment.To prepare the titanium dioxide by anodization dissolve 0.3 grams of ammonium fluoride and two milliliters of water into 100 milliliters of glycol in a 200 milliliter beaker with a stirrer to form the electrolyte. Place the beaker with the electrolyte into a 45 degree celsius water bath. Trim the titanium foil with scissors to 25 by 25 millimeters then polish the titanium foil surface with a 7000 mesh sand paper to remove the surface impurities.Submerge the titanium foil in a volumetric flask containing 15 milliliters of ethanol and then a flask with 15 milliliters of acetone. Now treat the foil for 15 minutes with an ultrasonic cleaner. Take out the titanium foil, rinse it three to five times with the ionized water and place it in a volumetric flask containing 20 milliliters of ethanol.Prepare the polishing solution in a 100 milliliter beaker as described in the text protocol. Now remove the titanium foil from the ethanol flask, rinse it three times with the ionized water and put it into the polishing solution for two to thee minutes. Remove the titanium foil and wash it with the ionized water an additional three times.Use an anoid alligator clip to hold the pretreated titanium foil and a cathode clip to hold a platinum foil. Place the two foils face to face in the electrolyte at a distance of two centimeters from each other. Turn on the direct current stabilized current power source, tune the voltage to 50 volts and electrolyze for 30 minutes.After the anodization has finished turn off the power and take out the titanium dioxide foil. Submerge the titanium foil in a volumetric flask containing 15 milliliters of ethanol and then transfer to a flask with 15 milliliters of acetone. Treat the titanium foil for 15 minutes with an ultrasonic cleaner.Following treatment, rinse the titanium foil three to five times with the ionized water and place it in 15 milliliter crucible. Put the crucible in an oven at 60 degrees Celsius for 12 hours to let the foil dry. Once dry, calcine the titanium dioxide foil in a muffle furnace under 400 degree Celsius for two hours with a heating rate of two degree Celsius per minute.To perform catalytic tests under concentrating light, clean the stainless cylinder shaped reactor with the ionized water. Then dry it in an oven at 60 degree Celsius for 10 minutes to ensure no interference from other carbon sources. After drying in the oven, add two milliliters of water, a stirrer and a catalyst holder to the reactor.Place a quartz glass with pours on the bottom of the holder and place the titanium dioxide catalysts on the center of the quartz glass. Now put thermal cup hole through an opening in the reactor wall and onto the catalyst surface. Add a Fresno lens on the top of the holder and seal the reactor with a quartz glass window.Place the reactor on the electromagnetic apparatus and check the air tightness with nitrogen. Feed the carbon dioxide into the reactor through a mass flow controller and flush the reactor at least three times to change the gas in the reactor to carbon dioxide. Place the Xenon lamp two centimeters directly above the reactor.Power on the Xenon lamp and adjust it's current to 15 amps then turn on the magnetic stirrers switch to start the reaction. Record the temperature change on the catalyst surface and in the gas. Analyze the product every hour using gas chromatography equipped with the flame ionized detector and a capillary column for separation of hydro carbons with one to six carbons.Calculate the number of products by the the external standard line method. Before quantifying the product build a standard curve of methane. Shown here is a device for concentrating photocatalytic reduction of carbon dioxide.XRD and SEM characterization of the catalyst showed that the prepared catalyst was a typical titanium oxide nanotube. Shown here is the catalyst under natural light. Under concentrating light the catalyst shows some shining.Here the x-ray diffraction pattern is shown, after concentrating light irradiation, to reveal crystal structure changes. The crystallinity is clearly improved after reaction under concentrating light. Methane yield is measured under natural and under concentrating light.The reaction rates of methane on different catalyst were significantly improved under the concentrating conditions. Pre-treatment of the catalyst with suitable gas would further increase the methane production rate. Following this procedure, other methods like concentrated photocatalysis under real sunlight can be performed in order to answer addition questions like photocatalytic splitting of water, and degradation of volatile organic compounds under real sunlight.After it's development, this technique paved the way for researchers in the photocatalytic field how to improve carbon dioxide photoreduction behavior in a photochemical system. Don't forget that working with concentrating light can be extremely hazardous and precautions such as googles should always be taken while performing this procedure.

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Engineering

6.6K visualizações.  Zhejiang University of Technology. Este método pode ajudar a responder a perguntas-chave no campo da fotossíntese artificial, como a fotoredução de dióxido de carbono ao metano. A tecnologia de concentração pode não apenas aumentar a intensidade da luz, mas também reduzir a quantidade de catalisador, bem como o volume do reator, ao mesmo tempo em que aumenta a temperatura de reação, aumentando assim a taxa de reação de fotoredução. Embora este método possa fornecer uma visão sobre a redução fotocatalítica d...