Reaction-Induced Phase Engineering of CuCo Nanoparticles for Enhanced Photothermal CO₂ Hydrogenation

Photothermal CO₂ hydrogenation is a promising approach for the conversion and valorization of CO₂ into value-added products. However, challenges remain in balancing catalytic activity, selectivity, and stability, particularly for non-noble metal catalysts. In this work, a phase engineering strategy is introduced to synthesize CuCo heterophase nanoparticles via in situ photoreduction of oxide precursors under CO₂ hydrogenation conditions. Experimental characterization reveals that the abundant Cu-Co₃Cu interfaces act as atomic-level channels for photoelectron transfer and localized hot charge accumulation. These features synergistically improve full-spectrum light utilization and photothermal conversion efficiency. The optimal catalyst achieves a CO yield of 0.82 mol g^-1 h^-1 under 3 W cm^-2 full-spectrum light illumination and maintains ≈95% selectivity across 100 cycles. In situ spectroscopy combined with theoretical calculations suggests that the phase engineering enhances CO₂ adsorption and activation while weakening CO binding, thereby suppressing methanation and enabling an optimal Sabatier balance. This interfacial engineering approach in heterophase nanostructures improves both stability and activity of non-noble metal catalysts in CO₂ conversion and offers an effective pathway for developing efficient photothermal systems through rational interfacial engineering.