Tailoring the properties of RhNi/CeO2 catalysts for improved chlorate reduction efficiency

Chlorate (ClO₃^-) are commonly identified oxyanions pollutant in the water environment, and catalytic hydrogenation reduction of oxyanions has emerged as a promising water treatment strategy. Supported Rh catalysts have been widely applied in the liquid phase catalytic hydrogenation due to their high activation capacity for H₂, while exploring highly active and stable catalysts for different pollutants remains a great challenge. The transition metal Ni was introduced into the Rh-based catalyst Rh/CeO₂ by the impregnation method to obtain the bimetallic catalyst RhNi₁₀/CeO₂, which was used in the catalytic hydrogenation reduction of ClO₃^-. In-situ DRIFTS identifies the highly dispersed Rh nanoparticles in the catalyst, and the strong metal-support interaction between the supported bimetallic Rh-Ni and CeO₂ supports is determined by XPS characterization. RhNi₁₀/CeO₂ exhibits an initial activity approximately 27 times higher than that of Rh/CeO₂. Furthermore, theoretical calculations corroborate the experimental observation that when chlorate is adsorbed on the Rh surface, the energy released increases with the introduction of Ni. We reveal the enhanced reactivity of the RhNi₁₀/CeO₂ through changing ClO₃^- concentration, which renders adsorption on catalyst surface pathway sequencely more favorable. In addition, the reusability of the catalyst was tested by adding chloride ions (Cl^-) and catalyst recycling. Results revealed that RhNi₁₀/CeO₂ maintained 100 % removal efficiency despite slight inhibition by Cl^- (12 times the ClO₃^- concentration of 0.4 mM). After 5 cycles, the activity loss remained below 9 % with 100 % removal efficiency. The bimetallic synergy leads to increased resistance to chloride ion interference, providing high catalytic stability.