Dynamic carbon cycling enables near-100% CO selective CO2 hydrogenation on carrier-free Cu catalyst

Conventional supported Cu catalysts for the reverse water-gas shift (RWGS) reaction suffer from activity-selectivity trade-offs and stability issues. Herein, we report a carrier-free Cu catalyst (bio-Cu) synthesized via a pollen-templated strategy. The template creates a hierarchical porous framework and enables in situ carbon doping (~4 wt%), ensuring homogeneous Cu dispersion and inhibiting agglomeration. In the RWGS reaction, the bio-Cu catalyst exhibits outstanding performance, achieving >99.1% CO selectivity with 25.3% CO 2 conversion at 340°C and 3 MPa, approximately 3.2 times higher than a conventional Cu benchmark. Under ambient pressure at 450°C, it maintains 30.5% conversion with 99.99% CO selectivity and shows exceptional stability over 100 h. Mechanistic studies reveal that carbon doping generates electron-deficient Cu δ+ species and promotes a synergistic carbon cycle that operates alongside the conventional redox pathway, collectively enhancing the catalytic efficiency. This work provides new insights into the rational design of high-performance, carrier-free CO 2 hydrogenation catalysts.