Intermetallic PdZn nanoparticles loaded on deficient TiO2 nanosheets as a support: a bifunctional electrocatalyst for oxygen reduction in PEMFCs and the glycerol oxidation reactions

Abstract

Exploring simple and flexible methods to synthesize an oxygen reduction reaction (ORR) catalyst with high catalytic activity is of great significance for the large-scale application of fuel cells. Here we developed an intermetallic PdZn on a TiO_2−x NS support catalyst by a simple strategy for large-scale production through an impregnation process involving low temperature annealing. This electrocatalyst prepared by a simple and single step exhibited better ORR activities in both acidic and alkaline solutions at room temperature with a higher value of electrochemical active surface area (ECSA). The repeated square-wave potential cycling test at 80 °C over 10 000 cycles confirmed the durability of the catalyst. The fuel cell using the PdZn/TiO_2−x NS catalyst showed a high power density of 855 mW cm⁻², which exceeds that of the PdZn supported carbon catalyst. Also, the proposed catalyst showed excellent stability over more than 100 h in proton-exchange membrane fuel cell (PEMFC) performance. Thus, the proposed TiO_2−x NSs will be an alternative to a carbon support in future PEMFC technology. Furthermore, PdZn/TiO_2−x NSs also showed higher activity and stability for the glycerol oxidation reaction (GOR) and higher selectivity for glycerate production than PdZn/C. Hence, the PdZn/TiO_2−x NS electrocatalyst opens up new avenues towards energy conversion devices such as DAFCs and metal–air batteries. This new study provides an opportunity for further research to rationally design more carbon free supported nanostructured intermetallics by using different transition metals for efficient electrochemical energy storage devices.