Preparation and Synergy of Supported Ru(0) and Pd(0) for Rapid Chlorate Reduction at pH 7

[Image: see text] Chlorate (ClO(3)(–)) is a common water pollutant due to its gigantic scale of production, wide applications in agriculture and industry, and formation as a toxic byproduct in various water treatment processes. This work reports on the facile preparation, mechanistic elucidation, and kinetic evaluation of a bimetallic catalyst for highly active ClO(3)(–) reduction into Cl(–). Under 1 atm H(2) and 20 °C, Pd(II) and Ru(III) were sequentially adsorbed and reduced on a powdered activated carbon support, affording Ru(0)–Pd(0)/C from scratch within only 20 min. The Pd(0) particles significantly accelerated the reductive immobilization of Ru(III) as >55% dispersed Ru(0) outside Pd(0). At pH 7, Ru–Pd/C shows a substantially higher activity of ClO(3)(–) reduction (initial turnover frequency >13.9 min(–1) on Ru(0); rate constant at 4050 L h(–1) g(metal)(–1)) than reported catalysts (e.g., Rh/C, Ir/C, Mo–Pd/C) and the monometallic Ru/C. In particular, Ru–Pd/C accomplished the reduction of concentrated 100 mM ClO(3)(–) (turnover number > 11,970), whereas Ru/C was quickly deactivated. In the bimetallic synergy, Ru(0) rapidly reduces ClO(3)(–) while Pd(0) scavenges the Ru-passivating ClO(2)(–) and restores Ru(0). This work demonstrates a simple and effective design for heterogeneous catalysts tailored for emerging water treatment needs.