Promotion of electrochemical CO2 reduction to ethylene on phosphorus-doped copper nanocrystals with stable Cuδ+ sites

Highlights: • Cu^δ+-rich nanocrystals induced by doping P are constructed by one-step reduction. • The electronic modulation of copper catalyst enhances CO₂RR for ethylene. • The favorable Cu^δ+ can be well reserved after the durability test. • Cu^δ+ with electron transfer improves intermediates adsorption for C-C coupling. Electrochemical reduction of CO₂ to C₂₊ products is a sustainable energy-driven pursuit for high added-value hydrocarbons. Tremendous efforts have been made to copper based electrocatalysts, which are well-known for producing C₂₊ products. However, being short of well-defined catalysts with stable Cu^δ+ electronic structure hinders its practical application and in-depth understanding. Herein, we developed a facile one-pot approach to prepare Cu^δ+-rich catalyst by doping phosphorus. Enhanced performance and tunable product selectivities are achieved due to the electron donor–acceptor interaction based on phosphorus content in series. C₂ hydrocarbons and alcohols are produced with high (~44.9%) selectivity, in which C₂H₄ (30.7 ± 0.9%) is dominant at −1.6 V vs reversible hydrogen electrode (RHE). This P-Cu catalyst shows a significantly higher current density (57.2 mA cm⁻²) compared to pristine Cu. In addition, the favorable Cu^δ+ is reserved during CO₂RR contributing to a long-term stability. Experimental results and DFT calculations demonstrate that the Cu^δ+ moiety facilitates the adsorption of carbon intermediates, C-C coupling and hence promotes the generation of C₂H₄ energetically. The well-designed catalyst indicates the profit of electronic structure engineering in designing catalysts for multiple-step chemical conversions.