Study On Preparation Of Boron/phosphorus Composite Photocatalysts And Its Photocatalytic Performance

As a mild technology,photocatalysis has good application prospects in energy and environmental area.In recent years,a variety of non-metallic semiconductor materials have attracted extensive attention from researchers due to their advantages such as environmental friendliness,rich content,low cost,and wide light absorption range.However,the photocatalytic activity is low due to the intrinsic properties of photogenerated charge composition,which limits the further application of these photocatalytic materials.In this paper,nonmetal boron and phosphorus composite photocatalysts were synthesized by different methods to improve the separation and migration of electron-hole pairs and thus improve the photocatalytic performance.The structure,morphology,composition and properties of the catalysts were characterized by a series of characterization methods.The photocatalytic degradation performance of the catalyst to malachite green and rhodamine B was studied under the condition of visible light,and the degradation mechanism was also explored.Firstly,sodium hypophosphite and commercial boron powder were used as raw materials to prepare different mass ratios of phosphorous and boron(P/B)composite photocatalysts by thermal decomposition method.The structure and morphology,chemical composition and photoelectric properties of the catalysts were analyzed by XRD,FT-IR,XPS,EDS,SEM,TEM and photoelectrochemistry methods.The experimental results showed that when the mass ratio of sodium hypophosphite and commercial boron powder is 3:1,the prepared photocatalyst has the highest activity.After 15 min of light irradiation,the degradation efficiency of malachite green can reach 99%,and the reaction rate constant is 14.8 times than that of commercial boron powder and 3.4 times than that of commercial red phosphorus.The results of free radical trapping experiments showed that h + and · O2-are the main active oxide species in the process of photocatalytic degradation of malachite green.The research results showed that red phosphorus is highly dispersed on the surface of elemental boron,and the surface modification can promote the transfer of electrons and inhibit the recombination of photo-generated electron-hole pairs of boron semiconductors,thereby improving the photocatalytic activity.Secondly,we used sodium hypophosphite and sodium borohydride as raw materials to prepare boron-phosphorus(B/P)composite photocatalysts with different molar ratios by thermal decomposition.The structure,morphology,chemical composition,and photoelectric properties of the catalysts were also studied.The experimental results showed that when the molar ratio of sodium hypophosphite and sodium borohydride is 5:1,the prepared photocatalyst has the best performance.After 60 min of illumination,the degradation rate of rhodamine B can reach 95.3%,and the reaction rate constant is 2.2 times than that of red phosphorus.And by transient photocurrent and electrochemical impedance spectroscopy,it can be proved that the surface modification of red phosphorus by boron can promote the separation of photogenerated charge pairs of red phosphorus,inhibit its photo-generated electron-hole pair ecombination,and thus improve its photocatalytic activity.In a word,the boron and phosphorus composite photocatalysts were synthesized by using different precursors.The two-component photocatalysts can promote the separation of photogenerated charges and improve the photocatalytic performance.This study provides a useful reference for the development of photocatalytic materials of composite nonmetallic elements.