Rational design of defect-rich tungsten-molybdenum oxide modified carbon supported Pd as superior performances electrocatalyst for formic acid oxidation

A novel defect-rich tungsten-molybdenum oxide modified carbon support (WMOx-C) is prepared by adsorption and calcination of mixed heteropolyacids on Vulcan XC-72 carbon. The Pd/WMOx-C and Pd/C catalysts are fabricated by the liquid reduction method. Results show that the Pd/WMOx-C exhibits a more even distribution and smaller particle size. Electrochemical measurements demonstrate that the Pd/WMOx-C presents superior electrocatalytic performances and stability than that of Pd/C. The mass activity and specific oxidation activity of Pd/WMOx-C are 3.04 and 1.89 times as those of Pd/C, respectively. In addition, the negatively shifted CO-stripping peak (59 mV than Pd/C), enhanced stability and lower charge transfer resistance value are observed for Pd/WMOx-C. The improvement of electrocatalytic performances of Pd/WMOx-C catalyst may be assigned to the uniformly dispersed Pd with smaller particle size, electronic tuning of Pd by WMOx, rapid change of the oxidation state of molybdenum with the redox couples Mo5+/Mo6+ and resultant defects of Pd/WMOx-C.