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.