Rational Precipitant Selection Enables Efficient CO2 Hydrogenation Toward Tailored CH4 and CO Product Selectivity

Direct conversion of CO2 into fuels or chemicals using solar energy has long been a topic of interest among researchers. However, the severe recombination of photogenerated carriers in photocatalysts often results in low conversion efficiency. To synergistically utilize both the light and thermal energy components of sunlight, this study designed a structurally simple Zn-Co bimetallic catalyst to enhance photocatalytic efficiency while lowering the temperature required for the thermal catalytic reaction. Through screening different precipitants, it was found that the Zn-Co catalyst prepared with NH3 as the precipitant exhibits outstanding activity for CO2 hydrogenation to methane at 240 °C, with CH4 selectivity exceeding 93%. Under the same conditions, the photothermal synergistic effect leads to an approximately 10% increase in turnover frequency (TOF). Structural characterization revealed that the NH3 precipitant effectively modulates the crystal phase, surface active sites, and electron transfer efficiency of the catalyst, thereby influencing the formation and desorption rates of key intermediates such as CO*, HCOO*, and *OCH3 during CO2 hydrogenation. The optimal photothermal synergy observed in this system further highlights the potential of catalyst design for achieving targeted product control.