Controllable Synthesis Of Au-TiO₂ Nanodumbbell Photocatalysts With Redox Region And Study On Its Photocatalytic Properties

Solar energy is considered one of the most ideal clean energy sources due to its inexhaustible,environmentally friendly,clean and pollution-free characteristics.Photocatalytic water splitting is one of the most widely promising strategies for converting solar energy into chemical energy.However,the development of photocatalytic water splitting still faces many practical problems.For example,the photocatalyst has low quantum efficiency?high photon-electron-hole pair recombination rate?,and the reverse reaction of H₂and O₂ is serious?remarkably reduces the efficiency of photocatalytic water splitting,and requires high gas separation costs in practical applications?.Therefore,it is of great significance to find a strategy that can achieve effective photocatalytic water splitting and suppressing reverse reactions.So far,Construction of one-dimensional?1D?hetero-nanostructured photocatalysts has been considered as one of the most effective strategies for inhibiting reverse reactions and achieving effective separation of photogenerated charges.Among the various structure materials,dumbbell-shaped one-dimensional heterogeneous nanostructures,such as Au-SiO₂,Au-Fe₃O₄,Cu_1.94S-CuS,Au-PbS?PbSe?,Cu-Ag,Ag-Fe₃O₄,have the great advantage on promoting the effective separation of photogenerated charges.However,the synthesis conditions of these dumbbell-shaped nanostructured materials are relatively complicated,and the growth mechanism is yet unclear.In this regard,we prepared Au NRs/TiO₂ nanodumbbell structure photocatalysts?Au NRs/TiO₂ NDs?by a gentle synthetic strategy.The TiO₂ nanoparticles?TiO₂ NPs?were only wrapped at both ends of Au NRs.Due to its unique structure,the photo-generated electrons-holes move in opposite directions to achieve their directional separation and form spatial redox region under light irradiation.Thereby,its effectively inhibiting the occurrence of reverse reactions.Based on this,Using the SEM,XRD,UV-vis to study the influencing factors of the structure of the controllable synthetic dumbbell,it was found that the temperature and acidity of the reaction process have a significant effect on the amount of TiO₂wrapped at the end of Au NRs.Based on this,we proposed the synthesis mechanism of Au NRs/TiO₂ NDs photocatalyst..Moreover,a series of photocatalysts of Au NRs/TiO₂ NDs with different TiO₂ coating degrees can be synthesized.Subsequently,the phase composition of Au NRs/TiO₂ NDs photocatalysts with different TiO₂ coating levels was analyzed by XRD.It was found that the bulk structure of Au NRs/TiO₂ NDs photocatalysts did not changes happened.Next,the above photocatalyst was applied to methanol as a sacrificial agent?CH₃OH?for photocatalytic water-splitting to produce hydrogen,the test conditions for hydrogen production at the end of Au NRs were maximum,the H₂ production rate could reach 60264umol/g/h,which is about 6 times reported Au/TiO₂ photocatalyst.And the electrochemical test results show that the greater the amount of TiO₂ wrapped at the end of Au NRs,the greater the photocurrent response density value,which further proves that the photo-generated electrons are injected from TiO₂ NP_S into Au NRs,and a reduction reaction occurs While the holes are left on TiO₂ NP_S,an oxidation reaction occurs,thereby realizing the partition of the redox reaction.When it is applied to photocatalytic water splitting,the reaction product of photocatalytic water splitting is accurately determined as O₂ through photocurrent responses of the electrochemical detection of trace oxygen and the H₂O¹88 isotope-labeled mass spectrogram.