Here, PdRu nanoparticle networks (NPNs) with various compositions were synthesized through an inex- pensive method in water as a green solvent, at different ratios of the H 2 PdCl 4 and RuCl 3 precursors. This is a fast, room temperature and surfactant free strategy which is able to form high surface area metal nanosponges with a three-dimensional (3D) porous structure. The structure of as-prepared nanosponges was characterized using the techniques of field emission scanning electron microscopy (FESEM), energy dispersive spectroscopy (EDS) and cyclic voltammetry (CV). Then, the electrocatalytic activities of PdRu NPNs towards formic acid oxidation were examined by electrochemical measurements including CV, chronoamperometry, and electrochemical impedance spectroscopy (EIS). Based on studies, it was found that the current density of formic acid oxidation (FAO) is strongly dependent on the composition of PdRu NPNs. The best performance was realized for Pd 4 Ru 1 NPNs compared to monometallic Pd counterpart and other bimetallic NPNs which might be ascribed to the role of Ru in the decrease of CO adsorp- tion strength on the catalyst and consequently the priority of formic acid oxidation through the direct pathway. The Pd 4 Ru 1 NPNs also showed the maximum current density and stability in chronoampero- metric measurements. In addition, comparative studies were performed between as-prepared NPNs and CNTs-supported Pd nanoparticles (Pd NPs/CNTs). The present results demonstrated the unique structural advantages of NPNs compared to individual Pd NPs supported on the CNT which leads to the promising performance of NPNs as supportless catalysts for the oxidation of formic acid.
