Enhancing The Photocatalytic Performance Of WO₃ Nanosheet Through Ohmic Contact And Exposed Facets Control

Semiconductor photocatalysis has the important application on the field of new energy and environment remediation.Therein,WO3 is widely concerned due to its superior stability and charge transport property.It is the focused subject to improve the photocatalytic performance of WO3.The charge separation efficiency and the contribution rate of surface active site are the major factors to affect the photocatalytic efficiency of WO3.on the basis of the above two factors,we fabricate W@WO3 Ohmic contact and WO3 nanosheet possessing the large proportion of high-energy facet,promoting the charge separation efficiency and the contribution rate of surface active site,and then enhancing the photocatalytic efficiency of WO3.The corresponding works are as follow:To enhance the charge separation efficiency,W@WO3 Ohmic contact is fabricated through W@WO3 core-shell composite which is synthesized by the nitric acid partial oxidation of tungsten powder and the thereafter heat treatment.XRD,SEM and TEM suggests that WO3 nanosheets are epitaxially grown on tungsten core to form the core-shell structure,and the thickness and density of WO3 shell can be controlled by acid concentration and reaction time.W@WO3 core-shell composite with a thinner and looser WO3 shell exhibits higher mineralization ability of acetaldehyde.Comprehensive analysis confirms the formation of Ohmic contact between W core and WO3 shell.The built-in electric field of Ohmic contact results in the migration of photogenerated electrons from WO3 shell to W core,which promotes the charge separation and then enhances the photooxidation ability of WO3.To enhance the contribution rate of surface active site,WO3 nanosheet possessing the different proportion of high-energy facet is obtained through adjusting the size of WO3 nanosheet by oxalic acid,lemon acid and P123 on the basis of the reaction between tungsten powder and nitric acid.XRD and TEM suggests that all the samples show the orthogonal crystalline phase of WO3,and the dominated exposed facet is(001)facet,which is the high-energy facet of orthogonal WO3.SEM indicates that the ordinal adding of oxalic acid,citric acid and P123 achieves the increase of the proportion of(001)facet.Photocatalytic performances are characterized by the degradation of acetaldehyde under UV light irradiation.The results indicate that WO3 nanosheet possessing the larger proportion of(001)facet shows the higher photodegradation ability and mineralization ability of acetaldehyde.This result is mainly attributed to the increase of surface active site of WO3 nanosheet.