Enhanced Photo‐Thermal CO<sub>2</sub> Methanation with Tunable Ru<sub>x</sub>Ni<sub>1‐x</sub> Catalytic Sites: Alloying Beyond Pure Ru
Chan Guo, Li Ge Wang, Yunxiang Tang, Zhengyi Yang, Yufei Zhao, Yanyan Jiang, Xiaodong Wen, Fenglong Wang
Abstract
Abstract Developing solid‐solution nano‐alloys from immiscible metals has garnered significant interest; however, the high formation entropy poses substantial challenges in synthesis, hindering a comprehensive understanding of the catalytic mechanisms under alloying effects. Herein, the synthesis of small‐sized (≈2.5 nm) Ru x Ni 1‐x solid‐solution alloy nanoparticles with precisely controlled Ru/Ni ratios across a broad compositional range is reported for the first time, despite their bulk immiscibility. The Ru 0.76 Ni 0.24 /TiO 2 catalyst, with an optimized Ru/Ni ratio, delivers superior photo‐thermal catalytic activity for CO 2 methanation, achieving a CH 4 production rate of 3.58 mol g metal −1 h −1 with 94% selectivity at 250 °C under light irradiation, representing a 2.82‐fold enhancement over monometallic Ru/TiO 2 . Comprehensive investigations reveal that the reconstruction of electronic structure at Ru–Ni active sites enhances the adsorption/activation of reactants, promotes the transformation of intermediate HCO 3 * to HCOO * , and facilitates the separation of the photo‐generated charge carriers witnessed by the femtosecond time‐resolved transient absorption (fs‐TA) spectroscopy. These combined effects collectively result in significantly enhanced CH 4 formation performance. This work highlights the potential of regulating catalytic sites in immiscible metal combinations for photo‐thermal catalytic CO 2 conversion, underscoring the promise of these cost‐effective alloys in heterogeneous catalysis.