Improve Nanometer Fe ₂ O ₃ Visible Strategies Of The Catalytic Properties And Mechanisms Of Insight

Recently, environmental pollution and energy crisis have become one of the mostserious challenges in current society. Among many solutions, the technology ofsemiconductor photocatalysis has been considered to be an effective method to solve theabove issues because it has the merits of simple operation, low power consumption, nosecondary pollution and so on. As we know that visible light takes up about44%in thesolar spectrum. Thus, synthesizing narrow band-gap photocatalysts with visibleresponse and high visible activity have practical implications. Among thesemiconductors with narrow bandgap, Fe2O3is an ideal semiconductor photocatalystdue to its wide light-response region，stable property and abundant storage. However,for practical application, Fe2O3usually exhibits low photocatalytic activity because thenanoparticles are apt to agglomerate and the photogenerated charges recombination rateis too high. Hence, we use the two methods of surface modification and constructingnanocomposite structures to improve the visible photocatalytic activity of Fe2O3, andthe mechanism of the enhanced photocatalytic activity is discussed in detail in thispaper.Firstly, we use phosphoric acid and SiO2to modify Fe2O3to enhance its thermalstability, so as to improve its visible photocatalytic activity. Base on the BET andhydroxyl radical analysis, it is suggested that the presence of modifying agents on thesurface suppresses the agglomeration of Fe2O3nanoparticles in the process of treatmentat high temperature, leading to the improved crystallinity, so as to promote thephotogenerated charge separation. Meanwhile, the small particle size and large specificsurface area were still kept.Secondly, TiO2-Fe2O3nanocomposites were constructed by coupling a smallamount of TiO2, in order to accelerate the high-energy photoelectrons transfer andimprove the visible photocatalytic activity of Fe2O3. And the photocatalytic activitycould be further improved by creating holes on the surface of TiO2by modification withH3PO4. On the basis of N2adsorption-desorption test, SPS experiment under differentatmospheres, TPV, O2-TPD and oxygen reduction current results, it is demonstrated that the enhanced photocatalytic activity is mainly due to the increased O2adsorptionamount on the material surface by modification with TiO2, leading to the prolongedlifetime and the improved photogenerated charges separation efficiency.This work would provide some new ideas to design and synthesize semiconductorphotocatalysts with high photocatalytic activity, and enrich the theory of photocatalysis.