RESUMO
A Pd3Bi intermetallic compound (IMC) was photocatalytically deposited onto the gallium oxide (Ga2O3) surface at room temperature. Conventional impregnation and reduction methods were difficult for the formation of the Pd3Bi IMC on Ga2O3, highlighting the importance of the photodeposition approach. The Pd3Bi-loaded Ga2O3 photocatalyst exhibited 84% selectivity in methane-to-ethane conversion with hydrogen production in the presence of water vapour.
RESUMO
Developing methane utilization technologies is desired to convert abundant and renewable carbon resources, such as natural gas and biogas, into value-added chemical products. This study provides insights into emerging photoelectrochemical (PEC) technology for the photocatalytic transformation of methane to C2H6 and H2 using visible light at room temperature. The PEC conversion of methane to oxygenates has been investigated in aqueous electrolytes. Herein, we demonstrate the gas-phase PEC methane conversion using a proton exchange membrane (PEM) as a solid polymer electrolyte and a gas-diffusion photoanode for methane oxidation. Tungsten trioxide (WO3), a semiconductor photocatalyst responsive to visible light, is utilized as the photoanode material. Ultraviolet light (â¼365 nm) excitation predominantly results in CO2 production with lower C2H6 selectivity in humidified methane. In contrast, visible light (â¼453 nm) effectively promotes C2H6 production over the WO3 photoanode, attributed to preferential hydroxyl radical (â¢OH) formation compared to UV irradiation. Photogenerated holes formed near the valence band maximum of WO3 contribute to â¢OH formation through a single-electron water oxidation. The photogenerated â¢OH activates gaseous methane molecules to methyl radicals, subsequently coupled into C2H6 at the gas-electrolyte-semiconductor boundary. H2 is concurrently formed on the cathode electrocatalyst. Improving the selectivity for the dehydrogenative coupling of methane is pivotal for enhancing the energy efficiency in the PEM-PEC system.