Platinum nanoparticles with TiO2–skin as a durable catalyst for photoelectrochemical methanol oxidation and electrochemical oxygen reduction reactions

Abstract

Performance degradation of Pt nanoparticles is considered to be among the most severe problems for electrochemical reactions. Pt–TiO2 catalysts are widely studied due to the optical effect of TiO2, which is beneficial for electron transfer during methanol oxidation. However, different configurations of these catalysts are insufficient in research. Here, we report rationally designed Pt nanoparticles with TiO2-skin as electrocatalysts for methanol oxidations and oxygen reduction reactions. Methanol oxidation current densities of the Pt–TiO2 nanoparticles are largely improved under irradiation. When the catalysts are tortured successive at ultrahigh current up to 1.0 mA cm−2, the potential-increase is as small as 90 mV. It shows good stability with a peak current fades of 4% after 250 cycles under illumination, compared with 13% in the dark. It also exhibits a much better oxygen reduction durability compared with Pt/C. By mechanism analysis, we believe the excellence in photoelectrochemistry is attributed to the TiO2-skin. The electrons generated in TiO2 spontaneously migrate to Pt nanoparticles, which provide a partially reducing atmosphere to prevent Pt nanoparticles from ionization and dissolution.