Study On Photoelectrocatalytic Water Splitting Properties Of Non-noble Metal Plasmons Nanomaterials

Plasmonic photocatalysts,coupled with noble metal nanomaterials and semiconductors,have been used in many fields such as water decomposition,environmental treatment and artificial photosynthesis.Local surface plasmon resonance（LSPR）is a unique optical property of rare noble metals（Au,Ag,Cu）under light irradiation.However,due to the low reserves and high cost of noble metals,their practical application in plasmon photocatalysis is limited.In recent years,some low-cost non-noble metal materials（metal oxides/sulfides）with LSPR phenomenon have attracted much attention as potential substitutes for plasmon noble metals.The free carrier density on metal oxides/sulfides can be improved by heavy doping.Similar to the LSPR of noble metals,the free carrier oscillation with incident light leads to strong LSPR.Among the non-noble metal plasmons,self-doped semiconductor such as WO_3-x,MoO_3-xand Cu_2-xS have attracted much attention because of their easy synthesis and strong LSPR absorption in the visible（Vis）and near-infrared（NIR）region,it has been used to promote photocatalysis and cancer treatment.Therefore,non-noble metal plasmon is a promising photocatalysis plasmon material.Based on the above analysis,MoO_3-xnanomaterial was introduced into photoelectrochemical water splitting material,and the photoelectrocatalytic activity of the material was improved through structure design.The details are as follows:1.Preparation of MoO_3-xpure non-noble metal plasmon nanolayer and study on the enhancement mechanism of photoelectrochemical catalysis.The generation of“hot electrons”in MoO_3-xpure non-noble metal plasmon nanomaterial can increase the charge density,promote the charges separation and transfer,and improve its catalytic performance.Due to the valence state of the MoO₃is easy to change,the color of MoO₃can change from white to blue in the reducing gas.MoO_3-xnanolayer was successfully prepared by ammonia reduction at low temperature.The structure（SEM/XRD）,optical properties（UV/FDTD）and photoelectrocatalytic properties（LSV/EIS）of MoO_3-xnanolayer were studied.It was found that their properties were significantly improved,which was attributed to the injection enhancement effect of"hot electrons"in MoO_3-xpure non-noble metal plasmons nanolayer.2.Construction of TiO₂-MoO_3-xheterostructure and study on enhancing mechanism of photoelectrochemical catalytic performance.TiO₂is coupled to MoO_3-xwith energy level matching and local surface plasmon resonance,and its photocatalytic activity is enhanced by manipulating a two-channel charge-carrier separation and transfer process.In this work,the TiO₂-MoO_3-xheterojunction was prepared by introducing the MoO_3-xnanolayer into the traditional TiO₂semiconductor.Mechanism characterization and control experiments have demonstrated the synergistic effects of two-channel carrier transfer paths in TiO₂-MoO_3-xheterojunction,including Z-scheme charge transfer and local surface plasmon resonance.Their interaction leads to the improvement of photoelectrocatalytic performance.3.Construction of Au-MoO_3-xplasmonic hybrid nanorod arrays and study on enhancing mechanism of photoelectrochemical catalytic performance.A novel metal/non-metal plasmon heterostructure system was fabricated by assembling MoO_3-xnanolayer onto an Au nanorod arrays,and the biplasmon coupling was proved.The local electric field of incident light can be amplified by the resonance excitation of MoO_3-xand Au in their hybrid structures.This process not only improves the generation and separation of hot electrons from plasmons,but also increases the local temperature of Au-MoO_3-xplasmonic hybrid nanorods arrays,thus enhancing the photoelectrocatalytic activity of the material.To sum up,the structure of MoO_3-xnon-noble metal plasmon nanolayer,TiO₂-MoO_3-xnon-noble metal plasmon/semiconductor heterojunction and Au-MoO_3-xplasmon hybrid nanorod arrays were fabricated by physical vapor deposition method,hydrothermal method,ammonia reduction method and AAO template method,the photoelectrocatalytic performance has been improved,and the corresponding photoelectrocatalytic mechanism has been analyzed.It provides a new idea for the further research and development of high efficiency plasmon photoelectrocatalytic material.