Manipulating the Coordination Environment of Cu Single Atoms via Regulating ZrO2 Support Crystal Phases for Enhanced CO2 Electroreduction

For electrochemical CO2 reduction (ECR), high-precision manipulation of the single-atomic catalytic centers is significant and remains an issue. Here, we report a support crystal phase engineering (SCPE) strategy by regulating the crystal phase of the ZrO2 support to modulate its interaction with Cu atomic centers, synergizing the coordination environment of Cu atoms and the local microenvironment for ECR. Specifically, tetragonal ZrO2 (tZrO2) supports a Cu1O3 structure, and the rich bridging O atoms at the tZrO2 surface could serve as basic sites. In contrast, the monoclinic ZrO2 (mZrO2) forming a Cu1O4 structure has weak basicity. The Cu1O3-tZrO2 site displays a high activity for ECR to methane, with 3.16 (FECH4) and 2.54 (jCH4) times higher than those of the Cu1O4-mZrO2 counterpart. Density functional theory (DFT) and attenuated total reflection surface-enhanced infrared absorption spectroscopy (ATR-SEIRAS) reveal that the dynamic *OH on Cu1O3-tZrO2 helps to significantly lower the Gibbs free-energy change (ΔG) for the rate-determining step (RDS). The rich basic sites on tZrO2 could also facilitate the adsorption and activation of CO2 and create an H2O-expelling local microenvironment to suppress the competing hydrogen evolution reaction. Our work demonstrates a facile strategy to simultaneously manipulate the coordination environment of the active centers and the local microenvironment for the catalytic reaction.