Synthesis Of Polyhedral Cu 2 O Crystals And Their Visible Light Degradation Properties

With the rapid development of industrialization,the national economy has gained a good trend of development.However,the environmental pollution brought about by industrialization has become more and more severe.Solving the problem of environmental pollution has become an urgent task.In environmental pollution,industrial wastewater pollution is the most important part of environmental problem.At present,scientists have taken many methods to solve the problem of wastewater pollution,but the effect is not good.Therefore,some scholars proposed photocatalytic degradation of organic wastewater.Photocatalytic degradation has been widely studied because of its advantages of low cost,environmental friendliness,and recyclability.Nowadays,Ti O₂ and ZnO are widely used,but due to the limited band gap of the material itself,it is impossible to make full use of too much energy.Finding a semiconductor photocatalyst with efficient use of solar energy has become a research hotspot.Cu₂O is a narrow band gap semiconductor and can absorb energy in visible light?visible light accounts for more than 40%of the total solar energy?,so it is an ideal semiconductor material.However,the existing Cu₂O-excited electrons and holes are not easily separated,which greatly limits the application of Cu₂O.Based on the resent research,there are two ways to improve the performance of Cu₂O:Firstly,reducing the Cu₂O particle size and increasing the large specific surface area to reduce the probability of recombination of holes and electrons.Secondly,the Cu₂O is modified or compounded with other semiconductors to accelerate the transfer rate of holes and electrons.This paper focuses on the limitation of Cu₂O materials.By controlling the different reaction parameters during the reaction process,the evolution of Cu₂O morphology is discussed in detail.Meanwhile,the influence of Cu₂O structure on photocatalysis is investigated.Cu₂O was prepared by method of precipitation using copper nitrate and copper chloride as precursors and hydroxylamine hydrochloride as a reducing agent.Cu₂O nanospheres were synthesized at 30?with the addition of sodium lauryl sulfate.The size of synthetized Cu₂O is between 0.2?m to 1.10?m.Many different structure Cu₂O particles have been obtained including spherical,octahedral,truncated rhombic dodecahedron,hexapod,and rhombic dodecahedral Cu₂O.The reaction factors have been investigated including copper source,reaction temperature,the amount of addition of sodium hydroxide.The experimental process was analyzed by X-ray diffraction?XRD?,field emission scanning electron microscopy?FESEM?and X-ray photoelectron spectroscopy?XPS?.Finally,it was found that when copper nitrate was used as the copper source,during the Cu₂O nucleation process,the preferential adsorption principle of SDS on the{110}plane dominated the growth direction of Cu₂O when controlling the amount of sodium lauryl sulfate added.The Cu₂O is a truncated cubic Cu₂O when the added SDS is continuously increased,the{111}plane rapidly decreases in area due to the faster growth rate,and finally the rhombic dodecahedron is obtained.In the preparation of Cu₂O with copper chloride as a copper source and controlling the amount of sodium hydroxide added,spherical,dodecahedron,and hex claw Cu₂O were synthesized by adjusting the amount of sodium hydroxide.Similar to the above principle,sodium hydroxide has a preferential adsorption principle.OH^-can be selectively adsorbed on the{111}plane of Cu₂O crystals and the growth rate is slowed along the{111}direction,controlling the synthesis of Cu₂O.Then the effect of reaction temperature on the structure of Cu₂O was investigated.By increasing the reaction temperature from 30?to 100?,different shapes of Cu₂O crystals with an average size of 0.42-1.21?m were prepared.The organic pollutants were simulated with methyl orange solution and the photocatalytic degradation performance of Cu₂O with different morphology and size under different reaction temperature conditions was analyzed.It was found that Cu₂O particles are the most critical factor affecting the performance of photocatalytic degradation.In this experiment,the photocatalytic effect of Cu₂O with a reaction temperature of 60?was found to be the best,and the degradation efficiency reached 96.79%.After undergoing 3 cycles of degradation,the removal rate of methyl orange by Cu₂O is still 93%,which proves that this kind of Cu₂O has good stability and provides a theoretical basis for the industrial production of Cu₂O.