Building of rich (111) grain boundary in copper for syngas in electrochemical CO2 reduction

Building of grain boundary (GB) in Cu-based catalysts has been demonstrated to be an efficient strategy to control the product selectivity of electrochemical CO 2 reduction reaction (eCO 2 RR). However, the fabrication and modulation of GBs in Cu are still challenging. In this study, a series of bare Cu catalysts with controllable density of Cu(111) GBs were investigated systematically for eCO 2 RR. These catalysts exhibit superior eCO 2 RR performance for syngas production with a high FE of ∼80 % and tunable H 2 /CO ratio of 0.46–2.78. Three-dimensional wormlike Cu with abundant (111) GBs displays a stable H 2 /CO ratio of ∼0.5 over a wide potential range from −0.9 to −1.2 V ( vs. RHE). In situ Raman and ATR-SEIRAS spectroscopy combined with DFT calculations reveal that Cu(111) GBs enhance the adsorption of CO 2 , lower the energy barriers of CO 2 to *COOH and *CO, further highlighting the potential to control syngas production with desirable proportion over Cu-based catalysts.