Constructing tightly integrated 2D conductive metal-organic framework/ TiO2 S-scheme heterostructure by chemical bonds for photocatalytic hydrogen evolution

Insufficient light energy utilization and the swift recombination of photogenerated carriers significantly constrain the efficiency of TiO2-based photocatalytic hydrogen (H2) evolution. To address this challenge, an innovative, tightly integrated S-scheme heterojunction Ag-BHT/TiO2 was constructed by introducing the conductive metal-organic framework (CMOF) Ag-BHT. X-ray photoelectron spectroscopy (XPS), free radical capture experiments, surface photovoltage spectroscopy (SPV) and density functional theory (DFT) calculations demonstrated the S-scheme electron transfer pathway between Ag-BHT and TiO2. The internal electric field (IEF) at the material interface facilitated the dissociation and transport of photogenerated carriers. The newly formed Ti-O-S bonds promoted electron migration from TiO2 to Ag-BHT. Highly conductive Ag-BHT established a highspeed electron transfer channel, accelerating the electron arrival on the surface. The pi-d conjugated structure and unique two-dimensional Ag-S network enable Ag-BHT to act as a visible light catcher and surface area expander. The findings indicated that 1 wt% Ag-BHT/TiO2 achieved an ideal H2 production efficiency of 4.813 mmol/g/h, representing pure TiO2 by a factor of 4.4. Notably, after five cycle tests, the H2 evolution rate of 1 wt% Ag-BHT/ TiO2 remained high at 4.574 mmol/g/h. This research offers a novel insight on creating efficient photocatalytic H2evolution systems and application of CMOFs in enhancing photocatalysis.