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Titanium dioxide (TiO2) has received extensive attention for photocatalytic hydrogen peroxide (H2O2) production, with the d-band center related to the adsorption performance, which affects the photocatalytic reaction process. Herein, an ingenious strategy to lower the antibonding-orbital occupancy in the Ti 3dorbital by fluoride ion (F−) doping is proposed, with density functional theory calculations predicting that F-doping into TiO2induces a non-uniform charge distribution and enables an upshift of the d-band center in F/TiO2. This manipulation provides accessible active centers with favorable d-band energy levels, which can improve the charge-transfer behavior, strengthen the interaction between the adsorbed oxygen and the photocatalyst, and reduce the adsorption energy of oxygen, eventually promoting the photocatalytic H2O2production rate. The experimental results further confirm that a lower antibonding-orbital occupancy can intensify the adsorption of atomic oxygen at the Ti sites. Electron paramagnetic resonance experiment reveals that the presence of F−ions in the lattice induces the formation of Ti3+centers that localize the extra electron needed for charge compensation. Femtosecond transient absorption (fs-TA) spectroscopy suggests that photogenerated electrons are transferred from the conduction band of F/TiO2to the Ti3+surface states and surface F−ions, expediting the separation of electrons and holes. Consequently, with F−doping in TiO2, the photocatalytic H2O2production yields improved from 277 to 467 μmol·g−1·h−1, with ethanol as a sacrificial reagent. This study provides a new strategy for regulating the d-band center to optimize the adsorption strength between the photocatalyst and oxygen atoms and achieve enhanced photocatalytic H2O2production performance.

Covalent organic frameworks (COFs) are porous crystalline materials with promising applications in photocatalysis, but their performance is greatly hampered by the fast recombination of photogenerated carriers. Herein, a hollow spherical COF was synthesized via the condensation polymerization of 1,3,5-tris(4-aminophenyl)benzene and 1,3,5-benzenetricarbaldehyde, and Au nanoparticles were in-situdeposited onto the COF through NaBH4reduction to ameliorate the photocatalytic performance. The composite exhibits impressive photocatalytic H2O2-production performance with the highest H2O2-evolution rate of 6067 μmol g−1h−1under visible light irradiation, which is about 1.9 times that of the pristine COF. The enhanced photocatalytic activity was ascribed to improved light absorption, abundant active Au sites, and efficient transfer and separation of photogenerated carriers in space. This work provides an avenue for designing high-performance H2O2-production photocatalysts by decorating porous COFs with active noble-metal sites.