Preparation Of Composite Photocatalytic Materials Based On Phosphorus Heterojunction And Its Applications Of Photocatalytic Energy Conversion

Direct conversion of light energy to chemical energy through semiconductor photocatalysts,which enables long-term stable storage and long-distance transfer of solar energy,is considered one of the most promising options for solving global energy and environmental problems.Reasonable design of photocatalytic materials and construction of efficient,stable and low-cost photocatalytic reaction system are the focus and difficulty of photocatalytic energy conversion research at present.As non-metallic semiconductor photocatalysts,black phosphorus（BP）and red phosphorus（RP）are abundant in nature and have appropriate band gap structures.This paper with phosphorus heterojunction as the main research goal,in view of the present based on the elemental phosphorus semiconductor catalyst in the light of the problems existing in the catalytic,from building heterogeneous structure and load method such as cocatalyst,the elemental phosphorus modification and study the properties of photocatalytic decomposition of water,in order to build efficient,stable,low cost of photocatalytic reaction system.Research of this paper is as follows:1.In view of the pure black phosphorus material only available light catalytic decomposition of water to produce hydrogen,by one step solvent thermal method synthesis BP/RP heterostructure used to photocatalytic water splitting to produce hydrogen and oxygen.The test results show that BP/RP can produce hydrogen and oxygen simultaneously without adding any sacrificial agent,with a rate ratio of 2:1.The content of black phosphorus in BP/RP heterojunction can be changed by changing the amount of red phosphorus in raw materials during solvothermal process,and the photocatalytic performance of BP/RP heterojunction is gradually improved with the increase of black phosphorus content.When the content of black phosphorus in the heterostructure is 21-22%,the composite material with the best photocatalytic results was obtained.2.Aiming at the problem that the photocatalytic hydrogen production rate of BP/RP heterogeneous structure is not ideal,the photocatalytic hydrogen production rate of BP/RP was improved by loading Co₃O₄nanoparticles on BP/RP as a cocatalyst by ultrasonic agitation method.In order to prevent the oxidation of phosphorus during ultrasonic agitation,the BP/RP surface was modified by adding PAH to improve its stability.The photocatalytic test results show that in comparison,PAH-BP/RP-Co₃O₄has a significantly higher rate of photocatalytic hydrogen production,11-fold higher than BP/RP.3.BP/RP-MBWO double heterostructure was constructed,and it was found that BP/RP-MBWO could be used not only to produce H₂,but also to produce H₂O₂.MBWO was prepared by one-step hydrothermal method,and BP/RP was loaded on MBWO to form BP/RP-MBWO double heterostructure by ultrasonic stirring method.The experimental results show that BP/RP-MBWO can generate hydroxyl radical and superoxide radical for H₂O₂production through water oxidation and oxygen reduction reaction respectively under visible light irradiation.Moreover,loading BP/RP on MBWO significantly improves the photocatalytic performance of BP/RP for H₂O₂production.When the loading amount was 20%,the composite material had the best photocatalytic performance.