Overcoming Copper Instability via Nickel Alloying for Efficient Plasmon-Catalytic CO₂ Hydrogenation

The development of efficient, stable, and low-coat plasmonic catalysts for CO₂ hydrogenation via the reverse water-gas shift (RWGS) reaction remains a significant challenge. Conventional Cu-based plasmonic catalysts suffer from poor stability due to the valence state fluctuation, nanoparticle sintering, and CO poisoning. Herein, we report a low-cost CuNi bimetallic plasmonic catalyst (CuNi/Al₂O₃) that address these bottlenecks, achieving a remarkable CO production rate of 4813 µmol/g/h under light irradiation at a relatively low temperature (300 °C), outperforming conventional Cu-based and noble metal catalysts. Systematic experimental and theoretical studies reveal that Ni incorporation enhances catalytic activity and stability by reducing activation energy, maintaining surface valence stability and suppressing nanoparticle sintering. In situ characterization further confirms that light not only drives the CO₂ hydrogenation via the localized surface plasmon resonance (LSPR) effect of Cu but also synergizes with Ni to suppress CO poisoning and promote surface reducibility, ensuring long-term stability. This work provides a rational design strategy for low-cost, stable Cu-based plasmonic catalysts and deepens the mechanistic understanding of alloy-mediated plasmonic CO₂ conversion, offering insights for advancing solar-driven CO₂ valorization.