Preparation And Photocatalytic Performance Of WS₂/Fe₂TiO₅ Inverse Opal Catalyst

Reusable energy and environmental remediation have become a critical matter of the society due to the fast-growing energy demand and the emission of pollutants during the existing manufacturing process.As a technology which can directly convert solar energy into chemical energy,Photocatalysis has provided a solution for solving energy problems.Although noble metals and usual semiconductors such as TiO₂,g-C₃N₄ have been widely applied to photocatalysis,their large-scale promotion has been limited in a certain extent as a result of their high costs and poor light absorption efficiency.Hence,it is emerged to develop photocatalysts with high light-utilization and low cost.In the past few years,photonic crystals(PCs)with the unique optical properties have attracted many interests of research ers,and PCs photons velocity can greatly decrease when the red band and blue band of bandgap overlap with the wavelengths of incident photons.Inverse opal photonic crystal is constructed by introducing the semiconductor precursor solutions into the photo nic crystal arrays,which has played a vital role in photocatalysis due to the dual advantage of enhancement of light absorption and slow photon effect.Although the range of narrow gap semiconductors absorption out of the ultraviolet region,the recombination of photo-generated carriers has been considered as one of the most important factors in the case of photocatalysis.In this paper,the performance of heterojunction photocatalyst modified with quantum dots has been improved by increasing the photo-generated carriers separation efficiency.The details are as follows:(1)An inverse opal photocatalyst with heterostructure was developed by loading WS₂quantum dots on the three-dimensional ordered macroporous framework of the3DOM Fe₂TiO₅.The photocatalytic nitrogen fixation experiments were conducted by using a variety of diverse structures photocatalyst.The inverse opal(IO)with macroporous can block the light transmission,leading to multiple scattering and prolonging the interaction time between photocatalysts and photon s,and thus the IO obviously improves the efficiency of light utilization.Therefore,compared to diverse sizes of inverse opals with narrow matching area,the 660 nm-Fe₂TiO₅(Fe₂TiO₅inverse opal prepared from polystyrene with diffraction peak at 660 nm as template)has shown an enhanced nitrogen fixation yield owing to the slow photon effect caused by wider band matching between the PBG of inverse opal and the EBG of Fe₂TiO₅.In contrast to Fe₂TiO₅ and the 660 nm-Fe₂TiO₅,the ammonia production rate of 660nm-Fe₂TiO₅-WS₂(heterojunction constructed by 660 nm-Fe₂TiO₅ loaded quantum dots)was 60.57 times as the Fe₂TiO₅ and 4.570 times as the 660 nm-Fe₂TiO₅.In addition,the heterojunction photocatalyst shows good selectivity,no byproduct(N₂H₄)and good recycle stability,which can be served as a practical role in photocatalytic nitrogen fixation.(2)In view of the excellent photogenerated carrier separati on performance of the inverse opal heterojunction catalyst,photocatalytic performance of the 660nm-Fe₂TiO₅-WS₂ was researched by the degradation of Rh B and MB.The macroporous framework and WS₂quantum dots strongly enhanced the chemical adsorption force between the catalyst surface and the dye molecules.Besides,the construction of heterojunction structure has improved the separation efficiency of the charge carriers,which increased the amounts of active molecules during the degradation process.Compared with Fe₂TiO₅ and the 3DOM Fe₂TiO₅,the degradation efficiency of heterojunction photocatalyst has significantly improved according to the synergistic effect of heterojunction and inv erse opal.660 nm-Fe₂TiO₅-WS₂ exhibited the fastest photocatalytic degradation of Rh B activity,which was about 2.94 and 4.82times as high as those of Fe₂TiO₅ and 660 nm-Fe₂TiO₅ under identical conditions.The result shows that the removal rate of MB under 660 nm-Fe₂TiO₅-WS₂ was 4.51 times as the Fe₂TiO₅,2.75 times as the 660 nm-Fe₂TiO₅,respectively.The 3DOM Fe₂TiO₅-WS₂has a facile preparation process,no need expensive raw materials and good stability,also it achieved effective degradation under light irradiation.In summary,heterojunction inverse opal can serve as a promising catalyst in the environmental protection.