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

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.