Regulation Of Interfacial Active Sites Based On TiO₂ Heterojunction And Photocatalytic Water Splitting Performance

The photocatalytic splitting of water to hydrogen in Semiconductor provides a feasible new scheme for alleviating the energy crisis and environmental governance in the 21st century.Titanium dioxide（TiO₂）,as the first photocatalytic material found to have the characteristics of photocatalytic water splitting to produce hydrogen and the most commercial application in the market,has always been favored by scientists.Among many applications,photocatalytic application is the field of TiO₂ material with the most in-depth research and the highest investment,which comes from the characteristics of TiO₂ material itself and the room for optimization.The wide band gap of TiO₂ leads to the rapid recombination of photo generated carriers and the response to ultraviolet light,which are the two most fatal defects of TiO₂,and it has also the focus of attention of researchers.In this paper,TiO₂ is used as the main material and the aim to optimize interfacial active sites on the TiO₂ through controllable composite method,and construct heterojunction composite photocatalyst with high-efficiency photocatalytic activity for water splitting.The research of this article is mainly carried out from two directions.（First）Construction of p-n junction.TiO₂ nanofibers（NFs）with uniform diameter and a large number of nano-particles used as the base material prepared by electrospinning.Co₃O₄ nanoparticles were grown in situ on TiO₂ NFs to construct a 0 D/1 D Co₃O₄/TiO₂ p-n junction composite material.The particles and pores accumulated by TiO₂ NFs are beneficial to enhance surface active sites.The porous outer-walls structure was also formed on surface of TiO₂ NFs with growth of Co₃O₄ NPs,increases active sites,optimizes interfacial charge transfer,and achieves excellent optical hydrogen production performance without precious metal loading under the full spectrum.The results of photoelectric and ESR tests combined with theoretical calculation show that the excellent performance is due to the effective inhibition of carrier recombination by the transmission mechanism of interface charge.（Second）Support of transition metal cluster cocatalyst.Combined with the current in-depth study and exploration of metal single atoms and atomic clusters.A large number of Cu support metal clusters（Cu SMCs）were loaded on the surface of TiO₂ by metal hot molten salt method to construct metal/semiconductor heterojunction photocatalyst.At the same time,the prepared TiO₂ nanoflowers have large specific surface area,which can provide sufficient anchor points for Cu.The existence of Cu SMCs was confirmed by high angle annular dark field scanning transmission electron microscopy（HAADF-STEM）and the chemical state of Cu was analyzed by high resolution X-ray photoelectron spectroscopy.The results prove that Cu/TiO₂-SMCs exhibits excellent photolysis water activity,which is attributed to the fact that a large number of Cu-SMCs on the surface continuously capture photogenerated electrons from TiO₂,and at the same time serve as catalytic reaction sites to promote the efficient photocatalysis of water splitting.Based on the excellent hydrogen production performance of Cu/TiO₂-SMCs,the ternary Cu/TiO₂/C heterojunction composite was constructed by introducing conductive non-metallic carbon materials as electron cocatalyst.Compared with all the comparative samples,Cu/TiO₂/C exhibits significantly enhanced water splitting activity.XPS,photoelectrochemical test and ESR test proved that Cu/TiO₂/C had excellent interface charge transfer,and photogenerated electrons could be captured by C and Cu-SMCs respectively,which realized the efficient charge separation mechanism of two channels and the synergistic effect of two active sites to promote the photocatalytic decomposition of hydrogen...