Study Of Surface Properties Regulation And Hydrogen Production Performance For InP-based Core-shell Quantum Dots

Artificial photocatalytic hydrogen production technology,particularly the development of a hydrogen production system based on quantum dot photocatalyst,is believed to be a powerful solution to future energy problems.In recent years,InP quantum dots(QDs)have emerged as potential candidates for photocatalysts due to their heavy metal-free composition and excellent visible light response.However,the stability of plain InP QDs photocatalyst is low,and the presence of more surface defect sites leads to non-radiative recombination of photogenerated electrons and holes,resulting in low photocatalytic efficiency.To address these issues,this thesis focuses on modifying InP QDs through core-shell engineering.By employing strategies such as structural design,interface engineering,and reaction temperature regulation,InP-based core-shell quantum dots were utilized to achieve efficient photocatalytic decomposition of hydrogen production.The main research contents of this thesis are as follows:(1)InP/ZnSe/ZnS gradient core-shell quantum dots were constructed by introducing a ZnSe intermediate layer.The ZnSe interlayer not only alleviates the lattice mismatch between InP and ZnS,but also the relatively small band gap of ZnSe reduces the constraint on excitons,which is more conducive to the migration of photogenerated electrons.Combined with timephotocurrent response,electrochemical impedance spectroscopy and steady-state fluorescence quenching experiments,the importance of the ZnSe interlayer to inhibit the recombination of photogenerated electron-hole pairs and promote the migration of photogenerated electrons to the surface was clarified,which is of great significance for improving the photocatalytic hydrogen production activity of InP-based core-shell quantum dots.The thickness of ZnSe layer and ZnS layer was optimized by structural control.Under the optimal conditions,the photocatalytic hydrogen production rate of InP/ZnSe/ZnS QDs could reach 84.29 μmol mg-1 h1,and the turnover number(TON)based on QDs exceeded 142000 within 16 hours.(2)An Sx-In-P1-x interface buffer layer was generated between the InP core and ZnS shell by anion exchange.Different shell thicknesses of InP/InPS/ZnS CBS(core/buffer/shell)QDs were obtained by using non-coordinating precursor S-ODE to regulate ion exchange and ZnS shell growth rate.Steady-state fluorescence spectra and time-resolved emission spectra showed that the interface buffer layer can effectively passivate the interface defects and inhibit exciton recombination.Transient absorption spectra and steady-state fluorescence quenching experiments confirmed that the interface buffer layer can accelerate the transfer rate of electrons and holes.Under the interface optimization,CBS-100 QDs exhibited excellent hydrogen production activity and stability.Under visible light irradiation,the hydrogen production rate can reach 102.04 μmol mg-1 h-1 within 16 h,and the TON exceeded 310000.