Fabrication Of Metal/Oxide Composite Nanomaterials By Photodeposition And The Applications In Electrocatalysis

Metal/oxide nanomaterials not only inherit the properties of single nano materials,but also the synergistic effect between metal and oxide can further improve the physical and chemical properties of nanocomposites.They have great potential in the fields of electronics,photonics,catalysis and biotechnology.To develop green,simple and safe preparation methods is still important.In this thesis,we propose the preparation of metal/metal oxide composite nanomaterials by photodeposition method.The preparation processes and the mechanism of photodeposition are studied and discussed.The optimized materials are used as efficient electrocatalytic hydrogen evolution reaction(HER)and oxygen evolution reaction(OER).The major results obtained are as follows:(1)Cu nanoparticles were successfully loaded on TiO₂by photodeposition which is simple and green.The influence of the crystal phase and load capacity of TiO₂on the preparation process was investigated.It was found that Cu nanoparticles can be highly dispersed on different crystalline TiO₂.P25 can obtain smaller Cu nanoparticles compared with that of anatase,and the main size is 0.8-1.5 nm.The results of HER performance show that the prepared nano materials have better activity,and small Cu nanoparticles are more favorable for hydrogen production.The performance of 10wt%-Cu/TiO₂(P25)is close to that of commercial Pt/C catalyst.The initial over potential of 10wt%-Cu/TiO₂(P25)is-170 mV which is close to-150 mV of commercial Pt/C(20%of Pt)tested on the same condition.The sample also showed good stability,the current density can be kept after 1000 laps.(2)The Au NRs/MnO₂core-shell composite were prepared by LSPR of Au nanorods(NRs).The results show that LSPR effect produced a large number of photothermal electrons on the surface of Au nanorods.MnO₄-is reduced to MnO₂and wrapped on the surface of Au NRs to form the Au NRs/MnO₂core-shell composite.The factors such as light source,sacrificial reagent and KMnO₄dosage are important factors in the preparation process.When there is without both sacrificing reagent and light irradiation,KMnO₄can directly oxidize Au NRs,which makes the Au NRs etched.Although a small part of the core/shell structure can be formed when there is light irradiation without sacrificing reagents,most MnO₂are in the solution rather than on Au NRs.The catalytic performance shows that under the condition of Au/Mn ratio of 1:0.5,Au NRs@MnO₂exhibits the best OER performance and can be enhanced by the irradiation of 520 nm light.In conclusion,the specific metal/oxide composite nanomaterials are successfully fabricated by photodeposition.The method is mild,simple,green and controllable.This study not only provides a new idea for the preparation of Au core-shell nanostructures,but also expands the applications of nanomaterials fabricated by photodeposition.