Unlocking Efficient Near-Infrared CO2 Photoreduction Over Metallic Photocatalysts Through Charge Polarization.

Metallic photocatalysts provide a promising route for utilizing low-energy near-infrared (NIR) photons in CO2 conversion because they bypass the bandgap constraints of conventional semiconductors. However, their intrinsically uniform electrostatic potential limits charge separation and CO2 adsorption/activation, thereby restricting their photocatalytic performance. Here, we report a charge polarization strategy that addresses this bottleneck through the synergistic incorporation of sulfur vacancies (Sv) and Au single atoms (Au SAs) in metallic NiCo2S4. The optimized AuSA/Sv-NiCo2S4 photocatalyst exhibits a 64-fold enhancement in activity relative to pristine NiCo2S4 under NIR irradiation without sacrificial agents, delivering CO and CH4 production rates of 1020 and 150 µmol g-1 h-1, respectively. Notably, it achieves a benchmark apparent quantum efficiency (AQE) of 1.24% at 800 nm and a solar-to-chemical energy conversion (STC) efficiency of 0.86% at room temperature. Mechanistic investigations reveal that charge redistribution reshapes the photocatalytic behavior of the metallic system in two complementary ways: it induces local polarization that suppresses charge recombination, and favors the formation of bimetallic Co3+⋯Ni2+ frustrated Lewis pair (FLP) sites for CO2 adsorption, activation, and *COOH generation. This work demonstrates charge polarization as an effective strategy for designing metallic photocatalysts, opening new opportunities for efficient solar-driven CO2 valorization.