Opening Direct Electrochemical Fischer-Tropsch Synthesis Path by Interfacial Engineering of Cu Electrode with P-Block Elements.

The electrochemical synthesis of syngas (CO and H2) has garnered considerable attention in the context of Fischer-Tropsch (FT) synthesis employing thermal catalysts. Nonetheless, the need for a novel, cost-effective technique persists. In this investigation, we introduce a direct electrochemical (dEC) approach for FT synthesis that functions under ambient conditions by utilizing a p-block element (Sn and In) overlaid Cu electrode. Surface *CO and H* species were obtained in an electrolytic medium through the CO2 + H+ + e- → HOOCad → *CO (or direct CO adsorption) and H+ + e- → H* reactions, respectively. We have observed C2-7 long-chain hydrocarbons with a CnH2n+2/CnH2n ratio of 1-3, and this observation can be explained through the process of C-C coupling chain growth of the conventional FT synthesis, based on the linearity of the Anderson-Schulz-Flory equation plots. Thick Sn and In overlayers resulted in the dominant production of formate, while CO and C2H4 production were found to be proportional and inversely correlated to H2, C2H6, and C3-7 hydrocarbon production. The EC CO2/CO reduction used in dEC FT synthesis offers valuable insights into the mechanism of C2+ production and holds promise as an eco-friendly approach to producing long-chain hydrocarbons for energy and environmental purposes.

New reaction path for long-chain hydrocarbons by electrochemical CO2 and CO reduction over Au/stainless steel.

The Fischer-Tropsch (F-T) synthesis is recognized for its ability to produce long-chain hydrocarbons. In this study, we aimed to replicate F-T synthesis using electrochemical CO2 reduction and CO reduction reactions on a stainless steel (SS) support with a gold (Au) overlayer. Under CO2-saturated conditions, the presence of Au on the SS surface led to the formation of CH4 and a range of hydrocarbons (CnH2n and CnH2n+2, n = 2-7), while bare SS primarily produced hydrogen. The Au(10 nm)/SS exhibited the highest hydrocarbon production in CO2-saturated phosphate, indicating a synergistic effect at the Au-SS interface. In CO-saturated conditions, bare SS also produced long-chain hydrocarbons, but increasing Au thickness resulted in decreased production due to poor CO adsorption. Hydrocarbons were formed through both direct and indirect CO adsorption pathways. Anderson-Schulz-Flory analysis confirmed surface CO hydrogenation and C-C coupling polymerization following conventional F-T synthesis. The C2 hydrocarbons exhibited distinct behavior compared to C3-5 hydrocarbons, suggesting different reaction pathways. Despite low reduction product levels, our EC method successfully replicated F-T synthesis using the Au/SS electrode, providing valuable insights into C-C coupling mechanisms and electrochemical production of long-chain hydrocarbons. Depth-profiling X-ray photoelectron spectroscopy revealed significant changes in surface elemental compositions before and after EC reduction.

Interface Engineered V-Zn Hybrids: Electrocatalytic and Photocatalytic CO2 Reductions.

V-Zn hybrids have widely been used as catalyst materials in the environment and as energy. Herein, V-Zn hybrid electrodes were prepared by the hydrothermal and sputter-deposition methods using a Zn foil support. Their electrocatalytic CO2 reduction (EC CO2 RR) performances were tested under various applied potentials, different electrolytes, and concentrations before and after thermal treatment of the demonstrated electrode. Gas and liquid products were confirmed by gas chromatography and nuclear magnetic resonance spectroscopy, respectively. For V-Zn electrode by hydrothermal method produced mainly syngas (CO and H2) with tunable ratio by varying applied potential. Minor products include CH4, C2H4, and C2H6. A liquid product of formate showed a Faradaic efficiency (FE) of 2%. EC CO2 RR efficiency for CO, CH4, and formate was best in 0.2 M KHCO3 electrolyte condition. CO and formate were further increased by photoirradiation and Nafion-treated electrode. Formate and CH4 productions were significantly increased by thermal treatment of the V-Zn electrode. CO production was diminished for the V-Zn electrode by sputter deposition but was recovered by thermal treatment. Photocatalytic CO2 RR was tested to find that RR products include CH3OH, CO, CH4, C2H4, and C2H6. Interestingly long-chain hydrocarbons (CnH2n and CnH2n+2, where n = 3-6) were first observed under mild conditions. The long-chain formation was understood by Fisher-Tropsch (F-T) synthesis. Alkenes were observed to be more produced than alkanes unlike in the conventional F-T synthesis. The present new findings provide useful clues for the development of hybrid electro-and photo-catalysts tested under various experimental conditions in energy and environment.

Photoelectrochemical CO2 Reduction Products Over Sandwiched Hybrid Ga2O3:ZnO/Indium/ZnO Nanorods.

Recycled valuable energy production by the electrochemical CO2 reduction method has explosively researched using countless amounts of developed electrocatalysts. Herein, we have developed hybrid sandwiched Ga2O3:ZnO/indium/ZnO nanorods (GZO/In/ZnONR) and tested their photoelectrocatalytic CO2 reduction performances. Gas chromatography and nuclear magnetic spectroscopy were employed to examine gas and liquid CO2 reduction products, respectively. Major products were observed to be CO, H2, and formate whose Faradaic efficiencies were highly dependent on the relative amounts of overlayer GZO and In spacer, as well as applied potential and light irradiation. Overall, the present study provides a new strategy of controlling CO2 reduction products by developing a sandwiched hybrid catalyst system for energy and environment.