Preparation And Modification Of Copper-based Oxides And Their Photocatalytic Decomposition Of Water And Oxidation Of Glycerol

With the vigorous development of the global economy,the consumption of traditional fossil energy is also rising,resulting in an increasingly prominent contradiction between energy crisis and economic development.Therefore,it is urgent to find and develop green,clean and sustainable new energy sources to replace fossil energy and promote the healthy development of society.Solar energy is currently one of the most utilized renewable resources,and the use of solar energy for photoelectrochemical（PEC）water splitting to produce hydrogen and glycerin oxide to produce high value-added by-products can not only alleviate the energy crisis and protect the environment,but also improve the economic benefits of crude glycerin.In this paper,copper-based oxides were used for the application of water splitting and selective oxidaton of glycerol.It is mainly divided into the following two parts:The first part:Cuprous oxide（Cu₂O）,a p-type semiconductor,is one of the most promising photocatalysts that can be used for efficient water splitting to produce hydrogen under light conditions.In this paper,Cu₂O films were prepared by electrodeposition and the relevant deposition parameters were optimized.In order to improve the water splitting performance of Cu₂O,the N element was successfully introduced into the Cu₂O film by simple ion doping method,and the photocathode prepared was at 0V vs.At the RHE voltage,the resulting photocurrent can reach up to2.90 m A/cm2,which is more than 2.6 times that of blank Cu₂O.In addition,through scanning electron microscopy on the microscopic morphology characterization,it is found that the morphology of the NO₃^-ion doped film is completely different from the blank,manifested as the accumulation of pyramid-like grains,and the formation of cluster-like bud structure,so as to arrange to form a complete morphology of the film.The mechanism of NO₃^-ion doping to increase photoelectric intensity was speculated through various characterization test methods,that is,due to the addition of NO₃^-,during the formation of Cu₂O,NO₃^-was adsorbed on the surface of the Cu₂O grain initially formed,resulting in the orientation growth of Cu₂O grain and the formation of flower clusters,and at the same time,NO₃^-was electrocatalytically reduced to NH3under the catalysis of Cu₂O and existed on the Cu₂O surface in the form of NH+4.Such a microstructure can promote the ultraviolet absorption of the film and the separation of photogenerated holes and electrons,thereby effectively enhancing the photocurrent intensity.Stability is an important index of Cu₂O photoelectrochemical performance,so in this paper,on the basis of NO₃^-ion doping,CuSCN hole transport layer is added as Cu₂O deposition substrate,and Ag coating and phenylacetyl copper protective layer are loaded on the outer surface respectively,and the effect of the two coating materials on the stability of Cu₂O film is compared.Through test characterization,it is found that the photocorrosion of Cu₂O film is inhibited to a certain extent under the Ag coating,and the CuSCN hole transport layer can enhance the photocurrent intensity of Cu₂O film,so as to obtain a higher starting potential during I-T testing.The second part:In this paper,CuO powder was synthesized by simple chemical precipitation reaction,CuO electrode was prepared by rotary coating method,and Bi element was creatively doped to improve the adsorption capacity of glycerol secondary hydroxyl group during the electrocatalytic process of CuO electrode.In addition,this paper adjusts and sets different external voltages,and investigates the changes of glycerol conversion and products under different voltage windows.By detecting the conversion amount and product type of glycerol at different voltages and selectively found that the voltage change did not cause a significant change in the amount of glycerol conversion,although ethanol was produced under different voltage conditions,the voltage was closely related to the type of main product.Under the high voltage window,the main product is mainly ethanol;In the relatively mild voltage range,the main product is methanol;The voltage continues to decrease and the main product becomes tartaric acid.