Preparation And Photocatalytic Carbon Dioxide Reduction Study Of Copper Oxide Based Composite Materials

With the qick development of the industry,the consumption of the fossil energy generates a large amount of greenhouse gases,which has baneful influence on the environment.Meanwhile,the crisis of fossil energy shortage emerges.Therefore,it is urgent to develop a sustainable development technology to reduce the concentration of greenhouse gases and generate available energy sources.Photocatalytic carbon dioxide（CO₂）reduction is effective,viable,and sustainable to solve the energy crisis and relieve the greenhouse gase effect.Photocatalytic CO₂ reduction can conver CO₂ to useful fuels（hydrocarbons,such as carbon monoxide,methane,methanol）by using the solar energy as the clean energy.And this techenology has been widely concerned by the science researchers and have the broad application prospect.At present,the photocatalytic CO₂ reduction technology is faced with the problem of low overall efficiency.And the photocatalyst is quite critical to solve the problem of low overall efficiency.Nowadays,there are many kinds of photocatalysts.And among of them,the copper oxides as the most common matter of nature exhibit great potential in the photocatalytic field owing to the unique band structure and resource advantages.However,the photocatalytic application of the copper oxides is restricted due to the shortages of easy photocorrosion,low solar utilization,and low photogenerated charge separation during the photocatalytic CO₂ reduction processes.In view of the above problems,this thesis adopts the morphological control,construction of heterostructures,and cocatalysts to improve the efficiency of photocatalytic CO₂ redcution for the cuprous oxide.The main researches are as follows:1.The Cu₂O growed on the surface of the Cu foam by the thermal oxidation process.Then,the ReS₂ was deposited on the Cu₂O/Cu foam by a drop-casting approach to prepare the ReS₂@Cu₂O/Cu photocatalyst.The UV-visible absorption spectroscopy（UV-vis Abs）and photoluminescence spectrometer（PL）analysis showed that the ReS₂@Cu₂O/Cu heterojunction structure can enhance the visible light utilization and improve the separation speed of electron-hole pairs.Under visible light irradiation,the CO yield of ReS₂@Cu₂O/Cu-180 is 10.56μmol/g?h.Through the characterization and analysis of band structures,the ReS₂@Cu₂O/Cu followed the S-scheme heterojunction.And the S-scheme heterojunction structure not only suppresses the recombination rate of carriers,but also increases the photoresponse range of visible light.2.Based on the heterojunction of ReS₂@Cu₂O/Cu,the Cu₂O quantum dots（Cu₂O QDS）growed on the surface of the ReS₂ by an in-situe method.And the effect of different Cu₂O QDS contents on the photocatalytic perfoemance was analyzed.Through the analysises of UV-vis absorption spectrum,photoluminescence spectrum and electrochemical impedance spectroscopy（EIS）,the Cu₂O-10/ReS₂ with 10 wt%Cu₂O QDS has the stronger visible light absorption,higher photogenerated carrier separation rate,and faster carrier transport capability.Under visible light irradiation for1 h,the CO yield of Cu₂O-10/ReS₂ was 30.11μmol/g,which was the highest and 1.85higher than that of ReS₂@Cu₂O/Cu-180.3.The Au and Pt were co-deposited on the Cu₂O QDs/ReS₂ heterojunction structure to form an indirect Z-scheme heterojunction and a Schottky junction,which further improved the performance and controllable selectivity of photocatalytic CO₂reduction.The results showed that under the synergistic effect of Au and Pt,the highest electron transfer rate of Au1-Pt5/Cu₂O/ReS₂ is 516.86μmol/g within 1 h of visible light irradiation,and this electron transfer rate is 7.58 times that of Cu₂O-10/ReS₂.Due to the strong interaction between Au and Pt atoms at the Au/Pt interface,the selectivity for CO and CH₄ can be easily tuned from 0 to 100%by adjusting the Au/Pt metal mass ratio.Therefore,Au1-Pt5/Cu₂O/ReS₂ provides a novel idea for photocatalytic CO₂reduction in terms of high catalytic activity and controllable selectivity.