Study On The Catalytic Performance Improvement And Mechanism Of Cuprous Oxide In Photo/Photoelectrocatalytic Degradation Of Organic Pollutants In Water

Visible light catalysis technology based on semiconductor materials is recognized as one of the most promising technologies to effectively solve the problem of environmental water pollution and energy crisis.The theoretical solar energy conversion efficiency of narrow band-gap p-type semiconductor cuprous oxide（Cu₂O）can reach 12%,and it is easily excited by visible light in the solar spectrum.Moreover,its characteristics of high natural abundance,low price and low toxicity make Cu₂O widely studied and paid attention in the field of visible light catalysis.However,due to its valence band position and redox potential,Cu₂O has the inherent defects of serious photogenerated carrier recombination and photocorrosion in water and light conditions,which will seriously hinder its catalytic activity,stability and reusability,thus restricting its further research and industrial applications.In this study,the photocatalytic system of Cu₂O powder and the photoelectrocatalysis system of Cu₂O thin film were studied respectively.The photocorrosion driven by the inherent charge characteristics of Cu₂O and the corresponding inhibition strategies were considered and discussed.For the thin film electrode,the photocorrosion inhibition strategy of Cu₂O under the influence of external bias is also considered.The external bias can force electrons to move to the counter electrode in a fixed direction through the external circuit,thus changing the transfer kinetics of Cu₂O photogenerated carriers.For the suspended powder materials,the copper-based organic frameworks（Metal-organic frameworks,MOFs）are used as precursors,and the organic frameworks,which protect the internal metal oxides,are transformed in situ into carbon frameworks with metal elements as the center through the improved program temperature rise method.The high conductivity of carbon materials is used to transfer the photogenerated carriers.XPS-VB,UV-Vis,PL and Mott-Schottky curves were used to prove that the highly conductive carbon components in derived materials cause band bending,and the internal electric field is established to promote the separation of Cu₂O photogenerated electron-hole pairs,thus improving catalytic activity and cycle stability.With ciprofloxacin（CIP）,a typical antibiotic,as the simulated pollutant,and a 6 W low-energy LED lamp as the experimental light source,the degradation kinetic constant reached 0.03958min^-1.After the four-cycle catalytic degradation experiment,the degradation efficiency of CIP could still reach 87.4%within 90 min.It has been proved that the carbonized derivative materials with Cu-based organic framework have excellent visible light catalytic activity,stability and reusability.A thin film of amorphous cobalt phosphate（Co-Pi）was modified by photoassisted electrodeposition on the surface of Cu₂O electrode.In previous reports,amorphous Co-Pi was used as a co-catalyst for oxygen evolution reaction（OER）to reduce the reaction potential.In this study,Co-Pi film was used as a hole transfer layer for the first time in the field of photocorrosion inhibition of electrode in the catalysis process.Due to the cyclic transformation of the chemical valence state of cobalt in the catalytic process,the holes of the valence band of Cu₂O were successfully transferred to the electrode/electrolyte interface,thus inhibiting the self-corrosion of the Cu₂O electrode in the long-term photocatalytic experiments.The photocurrent density curve of the electrode with time,the inductively coupled plasma emission spectroscopy（ICP-OES）and the characterization of the electrode material after long-term photoelectric testing were used to demonstrate the stability improvement of the modified electrode films.In this study,the catalytic activity and stability of the cuprous oxide composite was successfully improved by coupling carbon materials and amorphous cobalt phosphate modification methods,taking into account the different catalytic systems suitable for powder and thin film Cu₂O.At the same time,the separation and transfer paths of photogenerated carriers in the bulk and surface of the catalyst,the generation and transformation mechanism of active free radicals and the degradation process of organic pollutants were also investigated.