Breaking the Activity–Selectivity Trade-off in Low-Temperature CO 2 Hydrogenation: Spatial-Electronic Dual Regulation via Ca-Doped Core–Shell Catalysts for Efficient Methanol Synthesis

To address the challenging trade-off between activity and selectivity in low-temperature hydrogenation of CO 2 to methanol, this study employs a nanoreactor design strategy to construct a Ca-doped Cu-based core–shell catalyst (CZ@Cu 5 Ca 2 Zn 0.375 ). Under a low temperature of 200 °C, 5.0 MPa, and gas hourly space velocity (GHSV) = 9000 mL·g cat –1 ·h –1, this catalyst achieves a CO 2 conversion rate of 8.8%, methanol selectivity of 92.0%, and a space–time yield (STY) of 252.8 g·kg –1 ·h –1 . Ca doping introduces moderate basic sites and enhances the adsorption of CO 2 by utilizing the alkaline nature of Ca, thereby improving the surface utilization efficiency. Simultaneously, the core–shell structure preserves the integrity of the hollow sphere and provides a spatial confinement effect that increases local methanol concentration, facilitating its autocatalytic role in methanol synthesis. The synergistic integration of the Ca-based outer shell and the hollow core promotes CO 2 adsorption, strengthens the autocatalytic pathway, and suppresses side reactions. This cooperative design effectively breaks the traditional activity–selectivity trade-off and offers a strategy for low-temperature, efficient CO 2 -to-methanol conversion.