Light-induced synthesis of platinum/titania nanocapsules as an efficient, photosensitive and stable electrocatalyst

Abstract

Novel Pt/TiO₂ nanocapsules (NCs) having sizes of 40–100 nm and walls of 6–17 nm were successfully synthesized. The synthetic method concerns light-induced deposition of Pt nanoparticles into the mesopores of the present TiO₂ with average crystalline diameter of 3.3 nm. The as-prepared Pt/TiO₂ NCs with a distinguished hollow inner structure resulted in a high catalytic surface area. The mesoporous structure of TiO₂ NCs played an important role in avoiding Pt aggregation, which ensured high catalytic activity and stability. Furthermore, the TiO₂ NCs have photosensitivity, which enhances catalysis of oxygen reduction reaction (the half-wave potential is 0.76 V (vs. RHE) and the value of kinetic density at UV irradiation is 4.65 mA cm⁻² (at 0.7 V) under UV irradiation, which is more positive than dark condition (0.714 V; 3.34 mA cm⁻²)) and hydrogen evolution reaction (Corresponding Tafel slopes are 32 mV dec⁻¹ and 39 mV dec⁻¹ under UV irradiation and dark condition, respectively) on the surface of Pt/TiO₂ NCs under UV irradiation.