Preparation Of RP-based Photocatalytic Materials And Study On Their Photocatalytic Performance

Energy shortages and environmental pollution have become major global challenges.Photocatalytic technology has potential application prospects in solving energy shortage and environmental pollution,while developing new visible light photocatalysts with high-efficient charge carrier separation and wide spectrum response is the research hotspot in this field.The thesis has mainly studied nano-sized red phosphorus?RP?.Firstly,red phosphorus with three-dimensional nanostructure?3D-RP?was prepared by a hydrothermal method and high temperature annealed.The obtained 3D-RP exhibits excellent adsorption and reduction property.Take advantage of the excellent adsorption and reduction properties of red phosphorus,Au/RP composite was synthesized by an in-situ deposition method,Cu/RP composite and Ni₂P/RP hybrid was fabricated by an in-situ solvothermal method,and they were applied to photocatalytic splitting water into hydrogen.The mainly results are as follows:?1?Nano-sized red phosphorus was prepared by a hydrothermal method and high temperature annealed.The obtained RP exhibits three-dimensional and porous nanostructure,the BET surface area of RP can reach 54.3 m²/g and the adsorption edge is about 693 nm with a band gap about 1.79 eV.Due to the quantum size effect,the adsorption edge of nano-sized RP exhibits a slight blue shift compared with the commerical RP.It is found for the first time that nano red phosphorus can remove methylene blue?MB?and RhB during the dark static adsorption experiment.At the same time,it was found that red phosphorus could almost completely reduce Cr⁶⁺to Cr³⁺under light conditions,showing excellent photocatalytic reduction performance.In addition,the performance of photocatalytic decomposition of water to hydrogen production by red phosphorus under different sacrificial agents was compared,when the scavenger is triethanolamine?TEOA?,the average H₂ production rate of RP is 81.62?mol·g^-1·h^-11 under visible light irradiation.While the average H₂ production rate of RP is294.76?mol·g^-1·h^-11 using Na₂S/Na₂SO₃ as the scavenger.?2?Au/RP composite was synthesized by an in-situ deposition method.Cu/RP composite was fabricated by an in-situ solvothermal method,Au and Cu NPs are distributed uniformly on the surface of the RP,and the diameter varies from 4 nm to 6 nm.The local surface plasmon resonance effect?LSPR?of Au nanoparticles?Au NPs?and Cu nanoparticles?Cu NPs?enhanced the optical absorption and photocurrent of the samples significantly.The experiment of the photocatalytic decomposition of water to hydrogen showed that the photocatalytic H₂ production rates of Au/RP and Cu/RP were 2.32 times and 2.77 times higher than of RP.?3?Two-dimensional heterojunction Ni₂P/RP composite was fabricated by an in-situ alcoholthermal method.Ni₂P/RP heterojunctions with different content of Ni₂P were obtained by adjusting the original amount of NiCl₂·6H₂O in the precursor,Ni₂P and RP form a good contact interface.The H₂ production rate of the Ni₂P/RP-5 sample was 2183?mol·g^-1·h^-1under visible light irradiation with Na₂S/Na₂SO₃ as a scavenger,which was 7.41 times that of RP(294.76?mol·g^-1·h^-1).For comparison,the average photocatalytic H₂ evolution rate of 3.5wt%Ni₂P/RP(240.93?mol·g^-1·h^-1)with TEOA as a scavenger,which was approximately2.95 times higher than that of Pt/RP(81.63?mol·g^-1·h^-1).Meanwhile,it is found that the edge of RP surface is the active site of photocatalytic reaction,and the introduction of Ni₂P can increase more active sites of red phosphorus surface and promote the separation of electrons and holes.It is proved that the catalytic hydrogen production performance of Ni₂P is better than that of platinum.