The authors want to thank the Secretar&#237;a de Ciencia, Tecnolog&#237;a e Innovaci&#243;n de la Ciudad de M&#233;xico for the resources provided to carry out this work through the funded project SECITI/047/2016, and the National Funds for Scientific and Technological Development Chile (FONDECYT 11170431).

NOTE: Please read all the material safety data sheets (MSDS) before using the chemical reagents. Follow all the safety protocols by wearing a lab coat and gloves. Wear UV protection safety glasses during the photocatalysis tests. Be aware that nanomaterials may present important hazardous effects compared to their precursors.
1. Preparation of the BiOI microspheres
<ol>
	<li>For Solution 1, dissolve 2.9104 g of bismuth nitrate pentahydrate (Bi(NO3)3&#87...

<ol>
	<li>Yu, C., Zhou, W., Liu, H., Liu, Y., Dionysiou, D. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Design+and+fabrication+of+microsphere+photocatalysts+for+environmental+purification+and+energy+conversion.">Design and fabrication of microsphere photocatalysts for environmental purification and energy conversion.</a> Chemical Engineering Journal. 287, 117-129 (2016).</li><li>Wang, H., 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=Semiconductor+heterojunction+photocatalysts:+Design,+construction,+and+photocatalytic+performances.">Semiconductor heterojunction photocatalysts: Design, construction, and photocatalytic performances.</a> Chemical Society Reviews. 43 (15), 5234-5244 (2014).</li><li>Chou, S. Y., Chen, C. C., Dai, Y. M., Lin, J. H., Lee, W. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Novel+synthesis+of+bismuth+oxyiodide/graphitic+carbon+nitride+nanocomposites+with+enhanced+visible-light+photocatalytic+activity.">Novel synthesis of bismuth oxyiodide/graphitic carbon nitride nanocomposites with enhanced visible-light photocatalytic activity.</a> RSC Advances. 6, 33478-33491 (2016).</li><li>Siao, C. W., 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=Controlled+hydrothermal+synthesis+of+bismuth+oxychloride/bismuth+oxybromide/bismuth+oxyiodide+composites+exhibiting+visible-light+photocatalytic+degradation+of+2-hydroxybenzoic+acid+and+crystal+violet.">Controlled hydrothermal synthesis of bismuth oxychloride/bismuth oxybromide/bismuth oxyiodide composites exhibiting visible-light photocatalytic degradation of 2-hydroxybenzoic acid and crystal violet.</a> Journal of Colloid and Interface Science. 526, 322-336 (2018).</li><li>Meng, X., Zhang, Z. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Bismuth-based+photocatalytic+semiconductors:+Introduction,+challenges+and+possible+approaches.">Bismuth-based photocatalytic semiconductors: Introduction, challenges and possible approaches.</a> Journal of Molecular Catalysis A: Chemical. 423, 533-549 (2016).</li><li>Wang, Y., Deng, K., Zhang, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Visible+light+photocatalysis+of+BiOI+and+its+photocatalytic+activity+enhancement+by+in+situ+ionic+liquid+modification.">Visible light photocatalysis of BiOI and its photocatalytic activity enhancement by in situ ionic liquid modification.</a> Journal of Physical Chemistry C. 115 (29), 14300-14308 (2011).</li><li>Xiao, X., Zhang, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=De+Facile+synthesis+of+nanostructured+BiOI+microspheres+with+high+visible+light-induced+photocatalytic+activity.">De Facile synthesis of nanostructured BiOI microspheres with high visible light-induced photocatalytic activity.</a> Journal of Materials Chemistry. 20 (28), 5866-5870 (2010).</li><li>Chen, C. 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=Bismuth+oxyfluoride/bismuth+oxyiodide+nanocomposites+enhance+visible-light-driven+photocatalytic+activity.">Bismuth oxyfluoride/bismuth oxyiodide nanocomposites enhance visible-light-driven photocatalytic activity.</a> Journal of Colloid and Interface Science. 532, 375-386 (2018).</li><li>Xia, J., 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=Self-assembly+and+enhanced+photocatalytic+properties+of+BiOI+hollow+microspheres+via+a+reactable+ionic+liquid.">Self-assembly and enhanced photocatalytic properties of BiOI hollow microspheres via a reactable ionic liquid.</a> Langmuir. 27 (3), 1200-1206 (2011).</li><li>Mera, A. C., Contreras, D., Escalona, N., Mansilla, H. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=BiOI+microspheres+for+photocatalytic+degradation+of+gallic+acid.">BiOI microspheres for photocatalytic degradation of gallic acid.</a> Journal of Photochemistry and Photobiology A: Chemistry. 318, 71-76 (2016).</li><li>Pan, M., Zhang, H., Gao, G., Liu, L., Chen, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Facet-dependent+catalytic+activity+of+nanosheet-assembled+bismuth+oxyiodide+microspheres+in+degradation+of+bisphenol+A.">Facet-dependent catalytic activity of nanosheet-assembled bismuth oxyiodide microspheres in degradation of bisphenol A.</a> Environmental Science and Technology. 49 (10), 6240-6248 (2015).</li><li>Hu, J., 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=Solvents+mediated-synthesis+of+BiOI+photocatalysts+with+tunable+morphologies+and+their+visible-light+driven+photocatalytic+performances+in+removing+of+arsenic+from+water.">Solvents mediated-synthesis of BiOI photocatalysts with tunable morphologies and their visible-light driven photocatalytic performances in removing of arsenic from water.</a> Journal of Hazardous Materials. 264, 293-302 (2014).</li><li>Ye, L., Su, Y., Jin, X., Xie, H., Zhang, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Recent+advances+in+BiOX+(X+=+Cl,+Br+and+I)+photocatalysts:+Synthesis,+modification,+facet+effects+and+mechanisms.">Recent advances in BiOX (X = Cl, Br and I) photocatalysts: Synthesis, modification, facet effects and mechanisms.</a> Environmental Science: Nano. 1 (2), 90-112 (2014).</li><li>Qin, X., 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=Three+dimensional+BiOX+(X=Cl,+Br+and+I)+hierarchical+architectures:+Facile+ionic+liquid-assisted+solvothermal+synthesis+and+photocatalysis+towards+organic+dye+degradation.">Three dimensional BiOX (X=Cl, Br and I) hierarchical architectures: Facile ionic liquid-assisted solvothermal synthesis and photocatalysis towards organic dye degradation.</a> Materials Letters. 100, 285-288 (2013).</li><li>Chou, S. Y., 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=A+series+of+BiO+x+I+y/GO+photocatalysts:+synthesis,+characterization,+activity,+and+mechanism.">A series of BiO x I y/GO photocatalysts: synthesis, characterization, activity, and mechanism.</a> RSC Advances. 6 (86), 82743-82758 (2016).</li><li>Shi, X., Chen, X., Chen, X., Zhou, S., Lou, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Solvothermal+synthesis+of+BiOI+hierarchical+spheres+with+homogeneous+sizes+and+their+high+photocatalytic+performance.">Solvothermal synthesis of BiOI hierarchical spheres with homogeneous sizes and their high photocatalytic performance.</a> Materials Letters. 68, 296-299 (2012).</li><li>Di, J., 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=Reactable+ionic+liquid-assisted+rapid+synthesis+of+BiOI+hollow+microspheres+at+room+temperature+with+enhanced+photocatalytic+activity.">Reactable ionic liquid-assisted rapid synthesis of BiOI hollow microspheres at room temperature with enhanced photocatalytic activity.</a> Journal of Materials Chemistry A. 2 (38), 15864-15874 (2014).</li><li>Ren, 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=Controllable+synthesis+of+hollow/flower-like+BiOI+microspheres+and+highly+efficient+adsorption+and+photocatalytic+activity.">Controllable synthesis of hollow/flower-like BiOI microspheres and highly efficient adsorption and photocatalytic activity.</a> CrystEngComm. 14 (13), 4384-4390 (2012).</li><li>Lei, Y., 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=Room+temperature,+template-free+synthesis+of+BiOI+hierarchical+structures:+Visible-light+photocatalytic+and+electrochemical+hydrogen+storage+properties.">Room temperature, template-free synthesis of BiOI hierarchical structures: Visible-light photocatalytic and electrochemical hydrogen storage properties.</a> Dalton Transactions. 39 (13), 3273-3278 (2010).</li><li>Montoya-Zamora, J. M., Mart&#237;nez-de la Cruz, A., L&#243;pez Cu&#233;llar, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Enhanced+photocatalytic+activity+of+BiOI+synthesized+in+presence+of+EDTA.">Enhanced photocatalytic activity of BiOI synthesized in presence of EDTA.</a> Journal of the Taiwan Institute of Chemical Engineers. 75, 307-316 (2017).</li><li>He, R., Zhang, J., Yu, J., Cao, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Room-temperature+synthesis+of+BiOI+with+tailorable+(0+0+1)+facets+and+enhanced+photocatalytic+activity.">Room-temperature synthesis of BiOI with tailorable (0 0 1) facets and enhanced photocatalytic activity.</a> Journal of Colloid and Interface Science. 478, 201-208 (2016).</li><li>Song, J. M., Mao, C. J., Niu, H. L., Shen, Y. H., Zhang, S. Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hierarchical+structured+bismuth+oxychlorides:+self-assembly+from+nanoplates+to+nanoflowers+via+a+solvothermal+route+and+their+photocatalytic+properties.">Hierarchical structured bismuth oxychlorides: self-assembly from nanoplates to nanoflowers via a solvothermal route and their photocatalytic properties.</a> CrystEngComm. 12, 3875-3881 (2010).</li><li>Mera, A. C., V&#225;ldes, H., Jamett, F. J., Mel&#233;ndrez, M. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=BiOBr+microspheres+for+photocatalytic+degradation+of+an+anionic+dye.">BiOBr microspheres for photocatalytic degradation of an anionic dye.</a> Solid State Science. 65, 15-21 (2017).</li><li>Kong, X. Y., Lee, W. C., Ong, W. J., Chai, S. P., Mohamed, A. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Oxygen-deficient+BiOBr+as+a+highly+stable+photocatalyst+for+efficient+CO2+reduction+into+renewable+carbon-neutral+fuels.">Oxygen-deficient BiOBr as a highly stable photocatalyst for efficient CO2 reduction into renewable carbon-neutral fuels.</a> ChemCatChem. 8, 3074-3081 (2016).</li></ol>

We consider the mixture of the precursors as the critical step in the solvothermal synthesis of the BiOI microspheres. A very slow dripping of the KI solution into the Bi(NO3)3 solution (at a maximum of 1 mL/min) is crucial to obtain mesoporous microspheres, since it allows the slow formation and self-assembly of the [Bi2O2]+2 slabs, followed by the bonding with the iodide atoms to form the BiOI laminates. The lamellae are the bricks of the microspheres in the solvot...

A plethora of semiconductors has been synthesized so far, aiming for photocatalysts with high activity under visible light irradiation, either to degrade organic compounds or to generate renewable energy in the form of hydrogen1,2. Bismuth oxyhalides BiOX (X = Cl, Br, or I) are candidates for such applications because of their high photocatalytic efficiency under visible light or simulated sunlight irradiation3,4. The band gap energy (Eg) of bismuth oxyhalides decreases with the increase of the atomic number of the halide; thus, BiOI is the material displaying the lowest activation energy (Eg = 1.8 eV)5. Iodide atoms, bonded via Van der Waals force to bismuth atoms, create an electric field that favors the migration of the charge carriers to the semiconductor surface, triggering the photocatalytic process4,6. Moreover, the architecture of the crystallite has a critical role in the separa,tion of the charge carriers. Highly oriented structures in the (001) plane and 3D structures (such as microspheres) facilitate the charge carrier separation upon irradiation, increasing the photocatalytic performance7,8,9,10,11,12. In light of this, it is necessary to develop reliable synthetic methods to obtain structures that boost the photo-activity of the bismuth oxyhalide materials.
The solvothermal method is, by far, the most commonly used and studied route to obtain BiOI microspheres13,14,15,16. Some methodologies using ionic liquids have been also reported17, although the expenses associated with these methodologies can be higher. Microsphere structure is usually obtained using organic solvents such as ethylene glycol, which acts as a coordinating agent to form metallic alkoxides, resulting in a gradual self-assembling of [Bi2O2]2+ species18,19. Using the solvothermal route with ethylene glycol facilitates the formation of different morphologies by changing the key parameters in the reaction, such as temperature and reaction time4,18. There is a wide body of literature on synthetic methods to obtain BiOI microspheres, which shows contrasting information to achieve highly photoactive structures. This detailed protocol is aimed at showing a reliable synthetic method to obtain BiOI microspheres highly functional in the photocatalytic degradation of pollutants in water. We intend to help new researchers to successfully obtain this kind of materials, avoiding the most common pitfalls associated with the synthesis process.

<table>
	<tbody>
		<tr>
			<td>Bismuth(III) nitrate pentahydrate</td>
			<td>Sigma Aldrich</td>
			<td>383074</td>
			<td>ACS reagent, &#8805;98.0%</td>
		</tr>
		<tr>
			<td>Potassium iodide</td>
			<td>Sigma Aldrich</td>
			<td>746428</td>
			<td>ACS reagent, &#8805;98.0%</td>
		</tr>
		<tr>
			<td>Ethylene glycol</td>
			<td>Sigma Aldrich</td>
			<td>324558</td>
			<td>Anhydrous, 99.8%</td>
		</tr>
		<tr>
			<td>Ethanol</td>
			<td>Meyer</td>
			<td>5405</td>
			<td>Technical Grade, 96%</td>
		</tr>
		<tr>
			<td>Ciprofloxacin</td>
			<td>Sigma Aldrich</td>
			<td>17850</td>
			<td>HPLC, &#8805;98.0%</td>
		</tr>
		<tr>
			<td>Cary 5000 UV-Vis-NIR spectrophotometer</td>
			<td>Agilent</td>
			<td></td>
			<td>Used for the Band gap determination by the Tauc model.</td>
		</tr>
		<tr>
			<td>JSM-5600 Scanning Electron Microscope</td>
			<td>JOEL</td>
			<td></td>
			<td>Used for the SEM images.</td>
		</tr>
		<tr>
			<td>Autosob-1</td>
			<td>Qantachrome Instruments</td>
			<td></td>
			<td>Used for the determination of surface area and pore diameter.</td>
		</tr>
		<tr>
			<td>TOC-L Total Organic Carbon Analyzer</td>
			<td>Shimadzu</td>
			<td></td>
			<td>Used for determination of total organic carbon in water samples.</td>
		</tr>
		<tr>
			<td>Bruker AXS D8 Advance - X-ray Diffraction</td>
			<td>Bruker</td>
			<td></td>
			<td>Determination of crystal structure and crystallite size</td>
		</tr>
	</tbody>
</table>

a facile synthetic method to obtain bismuth oxyiodide microspheres highly functional for the photocatalytic processes of water depuration

Bismuth oxyhalide (BiOI) is a promising material for sunlight-driven-environmental photocatalysis. Given that the physical structure of this kind of materials is highly related to its photocatalytic performance, it is necessary to standardize the synthetic methods in order to obtain the most functional architectures and, thus, the highest photocatalytic efficiency. Here, we report a reliable route to obtain BiOI microspheres via the solvothermal process, using Bi(NO3)3 and potassium iodide (KI) as precursors, and ethylene glycol as a template. The synthesis is standardized in a 150 mL autoclave, at 126 &#176;C for 18 h. This results in 2-3 &#181;m-sized mesoporous microspheres, with a relevant specific surface area (61.3 m2/g). Shortening the reaction times in the synthesis results in amorphous structures, while higher temperatures lead to a slight increase in the porosity of the microspheres, with no effect in the photocatalytic performance. The materials are photo-active under UV-A/visible light irradiation for the degradation of the antibiotic ciprofloxacin in water. This method has demonstrated to be effective in interlaboratory tests, obtaining similar BiOI microspheres in Mexican and Chilean research groups.

3D microstructures of BiOI were successfully synthesized by the proposed synthetic method. This was confirmed by the SEM images shown in Figure 1a-c. The microspheres are formed from laminar structures of [Bi2O2]2+, which are bonded by two iodide atoms1. The formation of the microspheres depends on the temperature and time of the solvothermal procedure, as these paramet...

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A Facile Synthetic Method to Obtain Bismuth Oxyiodide Microspheres Highly Functional for the Photocatalytic Processes of Water Depuration

This article describes a synthetic method to obtain bismuth oxyiodide microspheres, which are highly functional to perform the photocatalytic removal of organic pollutants, such as ciprofloxacin, in water under UV-A/visible light irradiation.

Bismuth oxyhalide (BiOI) is a promising material for sunlight-driven-environmental photocatalysis. Given that the physical structure of this kind of ...

This protocol provides a reliable method to synthesize bismuth oxyiodide microspheres which are photocatalytically active under visible light irradiation. Here we present the key parameters that result in a successful synthesis of this kind of 3D structure via the solvothermal method. One of the main advantages of this method is that by varying key parameters such as temperature and time of heating, it is possible to obtain different structures.Microsphere leaf and flower-like structures have been obtained for instance. Through this method, it is possible to obtain photocatalytically active materials which have demonstrated to efficiently remove organic pollutants, bacteria and even heavy materials in polluted waters. To a higher scale, it is possible to use photocatalysis to clean water for human consumption.This method can provide some insights on the synthesis of other bismuth-based materials which have been reported as efficient in other catalysis reactions such as the oxidation of carbon monoxide as well as in artificial photosynthesis. To start preparing solution one, dissolve 2.9 grams of bismuth nitrate pentahydrate in 60 milliliters of ethylene glycol in a glass beaker. For solution two, dissolve one gram of potassium iodide in 60 milliliters of ethylene glycol in a glass beaker.Use a micropipette to add solution two to solution one drop by drop at a flow rate of one milliliter per minute to create a yellowish suspension. Abrupt addition of solution two will create a black color due to formation of bismuth tetraiodide anion. In such case, the synthesis must be aborted and started again.While making the precursor, it is necessary to wait until the disappearance of the yellow color from around the dripping solution before adding the next step of the potassium iodide to the bismuth solution. After stirring the mixture for 30 minutes at room temperature, transfer the mixture to a 150 milliliter autoclave reactor. Use ethylene glycol to rinse the beaker, swirl the beaker to remove the remaining suspension from the sidewalls, and tightly close the reactor.Place the autoclave reactor in a furnace. Set the temperature to 126 degrees Celsius at a temperature ramp of two degrees per minute and keep the reactor in the furnace for 18 hours. After that, take the autoclave reactor out of the furnace to cool down.Do not open hot reactor to avoid release of iodine gas. Adhere a 0.8 micrometer filter paper to the walls of a glass funnel. Pour the suspension from the reactor into the funnel and use ethylene glycol to rinse the reactor.Use deionized water and absolute ethanol to wash the solid retained on the filter for removing inorganic ions and ethylene glycol respectively. Alternate the washing solvent until the leachate is colorless. Use deionized water as the last washing step to remove any trace of ethanol.Place the product in the oven and set at 80 degrees Celsius for 24 hours. After that, separate the powder material from the filter to homogenize in an agate mortar. Then transfer the material into amber glass bottles in a desiccator.Put 30 milligrams of the samples into the sample port of the praying mantis accessory of the spectrophotometer. With a light source of 200 to 800 nanometers, irradiate the powder samples and continue as described in the manuscript. Band gap value obtained via this characterization would be around 1.8 electron volts.To make the 30 parts per million test solution, dissolve 7.5 milligrams of ciprofloxacin in 250 milliliters of distilled water. Then transfer the test solution to the photocatalytic reactor and thoroughly stir the solution at 25 degrees Celsius on a magnetic stir. From a pipeline, bubble dry air from a tank to the solution at 100 milliliters per minute to maintain air saturation.Position a 70 watt lamp at a five centimeters distance above the photoreactor. Add 62.5 milligrams of the bismuth oxyiodide microspheres to the test solution to achieve a load of 0.25 grams per liter. Immediately, use a glass syringe to take eight milliliters of the sample.Use a glass syringe to take the second eight milliliter sample for measuring the absorption of the organic molecule on the bismuth oxyiodide surface and then turn on the light. Take 12 samples after irradiation at the desired irradiation periods. Filter all the withdrawn samples by passing them through a nylon membrane.Store the filtered samples in glass vials at four degrees Celsius. Load the glass vials into the TOC device. This equipment analyzes the concentration of total and inorganic carbon remaining in the liquid samples through an infrared detector.3D microstructures of bismuth oxyiodide were successfully synthesized by the proposed synthetic method. SEM images show perfectly shaped spherical structures obtained by the solvothermal treatment at 126 degrees Celsius for 18 hours. Amorphous structures were observed when the solvothermal treatment was performed at 130 degrees Celsius for only 12 hours.Mesoporous microspheres of bismuth oxyiodide were achieved when a treatment was performed at 160 degrees for 18 hours. X-ray diffraction patterns of the bismuth oxyiodide microspheres obtained with 18-hour thermal treatment at 126 degrees Celsius and 160 degrees Celsius as well as a 0D bismuth oxyiodide material were compared. The decay in the peak intensity along with the broadening of the diffraction patterns showed the loss of orientation of the crystals when microspheres were obtained.The photocatalytic activity of the microspheres was assessed through the degradation of ciprofloxacin in pure water under UVA visible light irradiation. The bismuth oxyiodide washed with both ethanol and water showed higher mineralization rate than bismuth oxyiodide washed only with water. Photolysis was unable to completely oxidize the organic molecule.Please remember bismuth oxyiodide precursors are very unique. Thus, the addition of the iodide to the bismuth solution must be slow giving us a result the formation of the microsphere structures. Microspheres obtained by this method can be used in other environmental photocatalysis lines.It is necessary to test their capacity introduction reactions to produce hydrogen and also to reduce heavy metals in water. The development of this procedure paved the way to synthesize other 3D bismuth oxyiodide such as bismuth oxychloride or bismuth oxybromide which are known to potentially produce highly oxidative species.

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7.6K Views.  Universidad Nacional Autónoma de México. This protocol provides a reliable method to synthesize bismuth oxyiodide microspheres which are photocatalytically active under visible light irradiation. Here we present the key parameters that result in a successful synthesis of this kind of 3D structure via the solvothermal method. One of the main advantages of this method is that by varying key parameters such as temperature and time of heating, it is possible to obtain different structures.Microsphere leaf and flower-like structur...