Simultaneous Control over Lattice Doping and Nanocluster Modification of a Hybrid CuOx/TiO2 Photocatalyst during Flame Synthesis for Enhancing Hydrogen Evolution

Noble metal-free hybrid photocatalysts have recently been extensively studied for their applications in the environment and energy field. However, rational design over these photocatalysts is still a challenging task because the detailed mechanism of multi-component catalysts is not well understood yet. Here, we highlight a state-of-the-art approach, one-step flame spray pyrolysis (FSP), for preparing high-efficiency hybrid CuOx/TiO2 photocatalysts, where simultaneous control over lattice doping and nanocluster modification of Cu species on a TiO2 support is achieved. Effective engineering of Cu valence is achieved, where the surface Cu+ content varies from 15% to as high as 100%. Meanwhile, a high percentage (70-80 mol%) of TiO2 photocatalytic active phase (anatase) is also maintained in the flame-made catalysts. A dramatic enhancement in photocatalytic H-2 evolution efficiency of the hybrid catalyst is attained. The maximum photocatalytic H-2 evolution rate of the hybrid CuOx/TiO2 catalyst under Xe lamp in a methanol aqueous solution can reach as high as 112.6 mu mol h(-1), which is approximate to 22.1 times higher than that of commercial P25 TiO2. Mechanism investigation via density functional theory calculation and photoluminescence spectra validates that the bulk defect levels and surface-deposited CuOx nanoclusters play key roles in charge separation and extending spectral response.