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1. Characterization of Platinum Nanoparticles Utilized in Photocatalytic Hydrogen Synthesis*

   Boyce, Daniel; Colton, John; Richards, Matt (March 2018, Bulletin of the American Physical Society)

   As energy needs grow ever greater in today's world, many scientists are investigating possible replacements for fossil fuels as an energy source. The use of hydrogen (H2) gas in particular is undergoing a significant amount of research, but a major obstacle in the use of H2 for green, environmentally-friendly fuel is the energetic and chemical requirement to synthesize the gas. A possibility in satisfying current and future H2 production needs is the use of photocatalytic reactions, where a light-absorbing substance acts as a catalyst in shuttling electrons from a donor to protons that are reduced into H2. Previous research conducted at BYU found such a system where platinum nanoparticles bound to ferritin catalyzed the photoreaction of methyl viologen to reduce protons in an organic acid, which offered a one hundred-fold increase in H2 production efficiency over photocatalytic reactions catalyzed by bulk platinum. We are reporting on our efforts to optimize the synthesis of the platinum nanoparticles bound to ferritin that are used in this photocatalytic system and how we characterize these nanoparticles. *We'd like to thank the Brigham Young University Physics Department and the National Science Foundation (grant no. 1757998) for their generous funding. To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2018.4CS.J03.3 

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2. Biomimetic Catalysts Based on Au@TiO2-MoS2-CeO2 Composites for the Production of Hydrogen by Water Splitting

   https://doi.org/10.3390/ijms24010363  

   Fontánez, Kenneth; García, Diego; Ortiz, Dayna; Sampayo, Paola; Hernández, Luis; Cotto, María; Ducongé, José; Díaz, Francisco; Morant, Carmen; Petrescu, Florian; et al (January 2023, International Journal of Molecular Sciences)

   The photocatalytic hydrogen evolution reaction (HER) by water splitting has been studied, using catalysts based on crystalline TiO2 nanowires (TiO2NWs), which were synthesized by a hydrothermal procedure. This nanomaterial was subsequently modified by incorporating different loadings (1%, 3% and 5%) of gold nanoparticles (AuNPs) on the surface, previously exfoliated MoS2 nanosheets, and CeO2 nanoparticles (CeO2NPs). These nanomaterials, as well as the different synthesized catalysts, were characterized by electron microscopy (HR-SEM and HR-TEM), XPS, XRD, Raman, Reflectance and BET surface area. HER studies were performed in aqueous solution, under irradiation at different wavelengths (UV-visible), which were selected through the appropriate use of optical filters. The results obtained show that there is a synergistic effect between the different nanomaterials of the catalysts. The specific area of the catalyst, and especially the increased loading of MoS2 and CeO2NPs in the catalyst substantially improved the H2 production, with values of ca. 1114 μm/hg for the catalyst that had the best efficiency. Recyclability studies showed only a decrease in activity of approx. 7% after 15 cycles of use, possibly due to partial leaching of gold nanoparticles during catalyst use cycles. The results obtained in this research are certainly relevant and open many possibilities regarding the potential use and scaling of these heterostructures in the photocatalytic production of H2 from water. 

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3. Controlling product selectivity in hybrid gas/liquid reactors using gas conditions, voltage, and temperature

   https://doi.org/10.1039/D3NR00561E  

   Lee, Seung-Hoon; Iglesias, Brandon; Everitt, Henry O.; Liu, Jie (June 2023, Nanoscale)

   For the conversion of CO 2 into fuels and chemical feedstocks, hybrid gas/liquid-fed electrochemical flow reactors provide advantages in selectivity and production rates over traditional liquid phase reactors. However, fundamental questions remain about how to optimize conditions to produce desired products. Using an alkaline electrolyte to suppress hydrogen formation and a gas diffusion electrode catalyst composed of copper nanoparticles on carbon nanospikes, we investigate how hydrocarbon product selectivity in the CO 2 reduction reaction in hybrid reactors depends on three experimentally controllable parameters: (1) supply of dry or humidified CO 2 gas, (2) applied potential, and (3) electrolyte temperature. Changing from dry to humidified CO 2 dramatically alters product selectivity from C 2 products ethanol and acetic acid to ethylene and C 1 products formic acid and methane. Water vapor evidently influences product selectivity of reactions that occur on the gas-facing side of the catalyst by adding a source of protons that alters reaction pathways and intermediates. 

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4. Diiron Disulfide Methacrylate Metallopolymers as Sustainable Electrocatalysts for Water-Splitting and Molecular Hydrogen Production

   https://doi.org/10.1021/acsmacrolett.5c00567  

   Gibson, Arthur C; Glass, Richard S; Lichtenberger, Dennis L; Pyun, Jeffrey (October 2025, ACS Macro Letters)

   Rowan, Stuart J (Ed.)

   ABSTRACT: We review in this Viewpoint recent progress on the development of a new class of sustainable electrocatalytic systems for water-splitting and molecular hydrogen generation using diiron disulfide ([2Fe-2S]) active site methacrylate metallopolymers. To date, noble metal catalysts (e.g, platinum) remain the best electrocatalysts for molecular hydrogen generation using water as the chemical feedstock and proton donor. However, there remains a need for the synthesis of efficient electrocatalytic systems using low cost, earth abundant materials for sustainable H2 generation. We focus on our recent work in this area using well-defined single site [2Fe-2S]-metallopolymer catalysts. Thus far, these systems have demonstrated rates of hydrogen production >25 times faster than [FeFe]-hydrogenase enzymes and match the current densities of platinum with only 0.2 V higher potential when operating in water at neutral pH with tris(hydroxymethyl)aminoethane (TRIS) buffer (Faradaic yields 100±3%). The molecular design and synthesis of [2Fe-2S]-metallopolymers are reviewed along with mechanistic studies unraveling the causality of efficient H2 production from this catalytic system. The overall current output and overpotential are improved by (a) the reversible electrostatic adsorption of the metallopolymer on the carbon electrode surface that enhances the proton and electron transfer rates and (b) the use of protic buffer electrolytes (PBEs) that enhance the availability of protons. The schemes summarized here to improve the performance of [2Fe-2S] catalysts by incorporation into metallopolymers may be used to enhance the performance of other molecular electrocatalysts at the electrode surface. 

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5. Water Splitting Electrocatalysis within Layered Inorganic Nanomaterials

   https://doi.org/10.5772/intechopen.88116  

   Ramos-Garcés, Mario V; Sanchez, Joel; Barraza_Alvarez, Isabel; Wu, Yanyu; Villagrán, Dino; Jaramillo, Thomas F; Colón, Jorge L (February 2020, IntechOpen)

   Eyvaz, M; Yüksel, E (Ed.)

   The conversion of solar energy into chemical fuel is one of the “Holy Grails” of 21st century chemistry. Solar energy can be used to split water into oxygen and protons, which are then used to make hydrogen fuel. Nature is able to catalyze both the oxygen evolution reaction (OER) and the hydrogen evolution reaction (HER) required for the conversion of solar energy into chemical fuel through the employment of enzymes that are composed of inexpensive transition metals Instead of using expensive catalysts such as platinum, cheaper alternatives (such as cobalt, iron, or nickel) would provide the opportunity to make solar energy competitive with fossil fuels. However, obtaining efficient catalysts based on earth abundant materials is still a daunting task. Progress in finding an ideal catalyst for the OER has been challenging as it appears that the overpotential for these catalysts have plateaued. Recent theory has shown that nanoscopic confinement of catalysts into 3D frameworks increases stability and efficiency of catalysts for OER. We are studying the use of the layered inorganic nanomaterial zirconium phosphate (ZrP) for water splitting. In this chapter we review the advancements made with ZrP as a support for transition metals for the OER. Our studies have found that ZrP is a suitable support for transition metals as it provides an accessible surface where the OER can occur. Further findings have also show that exfoliation of ZrP increases the availability of sites where active species can be adsorbed and performance is improved with this strategy. 

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