Atomically\nTailored Zn-ZIF‑8 via RuNi Nanoalloy\nReplacement for Improved Photocatalytic H<sub>2</sub> Evolution

In this study, we developed a solid-state\natomic replacement method\nfor metal catalysts, enabling the exchange of metal atoms between\nsingle atoms and nanoalloys to create new combinations of nanoalloys\nand single atoms. We observed that partial metal interchange occurred\nbetween the RuNi nanoalloy and Zn from the zeolitic imidazolate framework-8\n(ZIF-8) on a carbon–nitrogen framework (CNF) at a high temperature\nof 900 °C, leading to the creation of RuZn nanoparticles and\nsingle nickel atoms (Ni-CN). Extended X-ray absorption fine structure\n(EXAFS) and X-ray absorption near edge structure (XANES) analyses\nrevealed that Ni is atomically dispersed within (RuZn)/Ni-CN. This\nfinding confirms the migration of Zn and Ni during the pyrolysis of\nthe RuNi@ZIF-8 precursor, providing definitive evidence of atomic\nreplacement. Due to the synergistic influence of RuZn nanocrystals\nand Ni-CN, the resulting (RuZn)/Ni-CN multisite catalyst exhibited\nsuperior hydrogen evolution reaction (HER) ability compared to the\nconventional nanoalloy-based catalysts. Density functional theory\ncalculations revealed that the integration of the (RuZn)<sub><i>n</i></sub> cluster on Ni surrounded with different N-coordinated\ncarbon structures enhanced HER activity with the optimized (RuZn)<sub><i>n</i></sub>/NiN<sub>2</sub>C<sub>2</sub> catalyst exhibiting\na low Δ<i>G</i><sub>H</sub> and improved electron\ncharge redistribution, thereby promoting favorable hydrogen adsorption.\nOur findings provide valuable insights into the design and optimization\nof photocatalysts through atomic-level engineering, opening new avenues\nfor efficient and sustainable energy conversion technologies.