PdPt-TiO2 nanowires: correlating composition, electronic effects and O-vacancies with activities towards water splitting and oxygen reduction

We report the optimization of both the support and the active phase of PdPt NPs supported on TiO2 nanowires to obtain highly active electro/photocatalysts for the oxygen reduction and water splitting reactions. This system displayed strong metal-support interactions, high concentration of oxygen vacancies, and PdPt NP were similar to 2 nm in size. By optimizing the loading of PdPt, both the photo- and electrocatalytic activities were improved compared to commercial materials. Interestingly, a volcano plot was obtained from the activity and the PdPt composition, and the Pd0.22P0.78-TiO2/C sample afforded the optimal performance. For instance, the amount of hydrogen produced from water splitting was 11.6 mmol/g(catalyst). For the ORR, the activity was similar to a commercial Pt catalyst, but a lower E-onset (0.87 V-RHE vs w 0.95 V-RHE) was detected. The variations in the activities with the composition correlated well with the variations in the electronic effects and the concentration of oxygen vacancies.