An Integrated Zn–CO 2 System With Ultralow Overpotential for Sustainable Hydrogen Production and Carbon Cycling

ABSTRACT The development of efficient electrocatalysts for sustainable hydrogen production integrated with CO 2 utilization is crucial for carbon‐neutral energy cycles. The metal‐CO 2 system exploits dissolution‐derived CO 2 under neutral conditions to co‐generate hydrogen and carbonate, offering a promising route for indirect CO 2 utilization. Here, this study develops a hierarchical Ni foam‐supported Pt‐Mo ionic cluster electrocatalyst (NiPtMoO x ) for efficient hydrogen evolution reaction (HER) with integrated CO 2 utilization. The catalyst achieves an exceptionally low overpotential of 142 mV at −100 mA cm −2 in KHCO 3 electrolyte, significantly surpassing commercial Pt/C (225 mV), while maintaining stability for over 1000 h. DFT calculations indicate that Mo doping optimizes the d ‐band center of Pt, thereby enhancing HER kinetics. When integrated into a Zn–CO 2 system, it co‐produces KHCO 3 and H 2 with a power density of 71.3 mW cm −2 , exceeding Pt/C by 37.6%. A scaled‐up Zn–CO 2 system with 100 cm 2 NiPtMoO x electrode delivers 1.27 W peak power and stable 100 h operation at 1 A. This work offers a synergistic approach for concurrent CO 2 utilization and energy‐efficient H 2 production, advancing integrated carbon mitigation and energy storage.