Enhanced Photocatalytic Hydrogen Generation from Methanol Solutions via In Situ Ni/Pt Co-Deposition on TiO2

TiO2 is widely utilized as an excellent photocatalyst in energy production. However, its rapid electron and hole recombination confers poor photocatalytic activity. Cocatalysts are essential for increasing photocatalytic efficacy by introducing improved electron transmission and enlarging the active site. Herein, the photocatalytic degradation of aqueous methanol solution to generate hydrogen was studied with the simultaneous in situ deposition of metals (M = Ag, Cu, Ni, Pd, and Pt) on the TiO2 surface. Adding methanol to water and incorporating a bimetallic cocatalyst enhanced hydrogen production by reducing the electron-hole pair recombination. The studied metal ions could be reduced by the conduction band electrons of TiO2 for the in situ simultaneous deposition of metal. The larger work function value of the studied metals favored the Schottky junction formation, which contributed to increasing photocatalytic efficiency. Among these simultaneous metal-deposited photocatalysts, maximal photocatalytic hydrogen production was achieved with NiPt/TiO2. The optimal component was 0.01 wt.% Ni/1.0 wt.% Pt for TiO2. The hydrogen evolution with NiPt/TiO2 was approximately 341 and 1.3 times better than that with pure TiO2 and Pt/TiO2, respectively. A potential reaction pathway for photocatalytic hydrogen production from an aqueous methanol solution over NiPt/TiO2 photocatalyst has also been proposed.