Interfacial Engineering For WO₃ Based Nanomaterials And Study In Photoelectrocatalytic Performance

The use of clean and abundant solar energy to solve energy shortage and environmental pollution has become the consensus of the international community.Recent years,as an effective way to solve the energy crisis and environmental problems,semiconductor photocatalytic technology has attracted more and more attention.In this paper,nanocomposites based on WO₃ electrodes were the research object.Aiming at designing excellent photoanode materials,the Photoelectrocatalytic properties were studied by regulate and control interface optimization of vertical WO₃nanoplates array.The main research contents are as follows:?1?Vertically grown WO₃ nanoplates?WO₃NP?were successfully fabricated by a one-step hydrothermal process using citric acid as a structure directing agent.Based on it,an innovative thioacetamide?TAA?etching method through wet chemical bath was developed to control WO₃NP electrode and improve its photoelectrocatalytic performance.After etching treatment,the surface roughness of WO₃NP was increased with large surface area,which may enlarge the absorption ability of sunlight.At the same time,etched WO₃NP possess more photoelectrocatalytic water oxidation active sites,accelerating the surface reaction kinetics.According to the analysis of crystal phase,it was found that?200?crystal plane of monoclinic WO₃ has obvious exposure in the etching process,showing a selective crystal phase control and promoting the separation of electrons and holes.The introduction of N–H and C–S groups narrow band gap which increasing the absorption range of visible light.Combined with the above factors,the etched WO₃NP electrode was showed excellent performance in photoelectric degradation of organic dyes.?2?Based on the vertically grown WO₃ nanoplates?WO₃NP?,carbon quantum dots?CQDs?were sensitized on the surface of it.Due to the good light absorption ability and effective electrons transfer,the CQDs sensitized WO₃NP electrode shows improved photoeletrochemical performance.In addition,low temperature calcination contributes to the enhanced performance by enhancing the bonding ability.The CQDs modified WO₃NP shows a superior ability to capture visible light and accelerate the separation of electrons and holes.Meanwhile,a lower onset potential can be obtained after sensitizing,which is caused by the change of band energy positions.?3?Based on the vertically grown WO₃ nanoplates?WO₃NP?,molecules interface engineering with silane grafting was proposed to form strong positive electricity on surface in semiconductor photocatalyst which named an external electric field?EEF?.A super charge density centre made by silane extracts the holes from bulk to the surface of photocatalyst for water oxidation and causes a fast bulk separation of photo-generated carriers to increase photocurrent.At the same time,the negative charge state in the interface between WO₃ and silane can further suppress the electron-hole recombination on the surface.Furthermore,a negative shift of onset potential is explained because of O and Si atomic orbital recombination caused by the band gap position change which accelerating the surface reaction of photoelectrocatalytic water oxidation.?4?Based on the vertically grown WO₃ nanosheets?WO₃NS?,silane molecules and Graphene oxide?GO?were successively anchoring on the surface of WO₃NS?WO₃NS/Si/GO?.The photocurrent performance of WO₃NS/Si/GO electrode was obtained significatantly improvement due to the synergic effect between silane molecules and GO.Silane molecules interfacial anchoring has demonstrated the improved charge carriers separation ability both in bulk and surface by constructing the EEF.Then the separated electrons-holes on the WO₃NS can further quickly transfer to GO which is acting as a charge carriers transfer channel,preventing the surface charge carriers accumulation.In addition,the synergy of silane molecules and GO also accelerate oxidation evolution reaction kinetic by increasing the activity and quantity of reactive sites.In this dissertation,our research work focuses on the internal relation between regulation and Photoelectrocatalytic properties for electrode.We hope that this work could provide the theoretical and experimental basis for studying the surface state,electric field building and catalytic law of photoelectrode,as well as the future optimization design.