Renewable energy-powered electro-reduction of carbon dioxide (CO2) to value-added multi-carbon fuels (i.e., ethylene) is widely recognized as a promising approach to address issues of global warming and future energy crisis. However, in most cases, selective and large-current ethylene (C2H4) production from CO2 reduction reaction (CO2RR) is only achieved in strong alkaline electrolytes, which react with CO2 to generate a large amount of carbonate for blocking the electrocatalysts and thus resulting in the sharp deactivation. Here, a robust strategy that combines the selection of specific electrolyte and structural design of electrocatalysts has been developed to artificially create a strongly alkaline and K+-rich interfacial microenvironment for reducing thermodynamic barriers towards the CO intermediate generation and C-C coupling, which in turn significantly promotes the generation of ethylene in a neutral electrolyte. Specific, a low buffering capability of KCl aqueous solution is selected as the electrolyte to increase the interfacial pH, and porous Cu nanowires are designed and prepared as electrocatalysts to increase interfacial concentration of K+ by pore-induced electric field-enhanced effect. Moreover, the abundant defects on the Cu nanowires have high ability to capture OH- for further increasing the interfacial pH. As a result, excellent performance is achieved by using a flow-cell in a neutral electrolyte, such as a large CO2-reduction current density of 329.6 mA cm-2 along with a high Faradaic efficiency (FE) of 71.2% towards C2H4, and outstanding stability of 100 h. Clearly, our work paves new pathways to achieve highly efficient and stable C2H4 production from CO2RR in a neutral media by tuning the interfacial micro-environment.

Tuning interfacial microenvironment to enable selective carbon dioxide electro-reduction to ethylene in neutral electrolytes

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