Hydrothermal Fabrication of Carbon-Supported Oxide-Derived Copper Heterostructures: A Robust Catalyst System for Enhanced Electro-Reduction of CO2 to C2 H4.

Anthropogenic CO2 can be converted to alternative fuels and value-added products by electrocatalytic routes. Copper-based catalysts are found to be the star materials for obtaining longer-chain carbon compounds beyond 2e- products. Herein, we report a facile hydrothermal fabrication of a highly robust electrocatalyst: in-situ grown heterostructures of plate-like CuO-Cu2 O on carbon black. Simultaneous synthesis of copper-carbon catalysts with varied amounts of copper was conducted to determine the optimum blend. It is observed that the optimum ratio and structure have aided in achieving the state of art faradaic efficiency for ethylene >45 % at -1.6 V vs. RHE at industrially relevant high current densities over 160 to 200 mA ⋅ cm-2 . It is understood that the in-situ modification of CuO to Cu2 O during the electrolysis is the driving force for the highly selective conversion of CO2 to ethylene through the *CO intermediates at the onset potentials followed by C-C coupling. The excellent distribution of Cu-based platelets on the carbon structure enables rapid electron transfer and enhanced catalytic efficiency. It is inferred that choosing the right composition of the catalyst by tuning the catalyst layer over the gas diffusion electrode can substantially affect the product selectivity and promote reaching the potential industrial scale.