Electrochemical reduction of CO2 to high value-added hydrocarbon fuels and chemicals has emerged as an effective strategy to achieve carbon neutrality.In conventional electrocatalytic powder-coated electrodes fabricated by spraying method,poor contact between electrocatalyst and substrate can severely impact the electrocatalytic activity and stability.Herein,a self-supporting nanotree electrode(Bi@Cu NTs)for efficient electroreduction from CO2 to formate was structured by combing facile electrodeposition method and galvanic replacement reaction.The advantages of self-supporting nanotree structure including:1)minimization of the interfacial resistance and improvement of the spatial structure stability;2)rich active sites and plentiful pore structures.The charge transfer resistant could be effectively reduced while ensuring the stability of the electrode operation.Results demonstrated that the prepared Bi@Cu NTs electrode exhibited outstanding performance for CO2 conversion in both electrochemical activity and long-term operation stability.In a wide operating potential window from-1.4 to-0.8 V(vs.RHE),the proposed Bi@Cu NTs electrode presented excellent formate selectivity,where the Faradaic efficiency of CO2-to-formate(FEFormate)at each operating potential was above 90％.Typically,at-1.2 V,the proposed electrode achieved a high FEFormate of 97.9％and a current density of 170.6 mA·cm-2,simultaneously.Meanwhile,the self-supporting Bi@Cu NTs electrode also revealed excellent stability in a long-term operation,as evidenced by maintaining an average FEFormate of more than 90％and an average current density higher than 110 mA·cm 2 over 50 h of continuous electrolysis at a controlled potential of-1.0 V without any degradation in performance.
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