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

The development of efficient electrocatalysts for sustainable hydrogen production integrated with CO₂ utilization is crucial for carbon-neutral energy cycles. The metal-CO₂ system exploits dissolution-derived CO₂ under neutral conditions to co-generate hydrogen and carbonate, offering a promising route for indirect CO₂ 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 CO₂ utilization. The catalyst achieves an exceptionally low overpotential of 142 mV at -100 mA cm^-2 in KHCO₃ 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-CO₂ system, it co-produces KHCO₃ and H₂ with a power density of 71.3 mW cm^-2, exceeding Pt/C by 37.6%. A scaled-up Zn-CO₂ system with 100 cm² 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 CO₂ utilization and energy-efficient H₂ production, advancing integrated carbon mitigation and energy storage.