Simultaneous Control over Lattice Doping and Nanocluster Modification of a Hybrid CuO_x/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 CuO_x/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 H₂ evolution efficiency of the hybrid catalyst is attained. The maximum photocatalytic H₂ evolution rate of the hybrid CuO_x/TiO₂ catalyst under Xe lamp in a methanol aqueous solution can reach as high as 112.6 µmol h⁻¹, which is ≈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 CuO_x nanoclusters play key roles in charge separation and extending spectral response.