| Energy crisis and environmental pollution are the most serious problems in human society.Many methods have been tried to achieve energy regeneration and environmental protection.Global carbon dioxide emissions have attracted wide attention.The greenhouse effect caused by carbon dioxide causes serious climate and environmental problems.However,carbon dioxide is also a potential carbon resource,and all countries are competing for its research,development and utilization.With the progress of science and technology,especially in the field of chemical synthesis,new technologies and new catalysts have created conditions and possibilities for the synthesis of chemical products by carbon dioxide gas.At present,an ideal solution to carbon dioxide problem is the development of solar energy by artificial photosynthesis,and the reduction of carbon dioxide to generate high-energy compounds under the action of photoinduced reduction of solar energy.The development of CO2 utilization technology can not only save fossil resources such as oil,natural gas and coal,but also turn it into treasure.It can reduce the environmental pollution caused by CO2 and have obvious economic and environmental benefits.Photocatalytic reactions are realized by photogenerated electrons and holes after irradiation.The photoelectric catalytic reduction of CO2 can directly utilize solar energy,which can truly realize the resource utilization of CO2.Among most semiconductors,Cu2O is able to utilize visble light and the electrons from its conduct band is suitable for CO2 reduction.In this paper,nanostructual Cu2O thin films were prepared by different methods,and their applications in photocatalytic carbon dioxide reduction and photoelectrocatalytic conversion of methane were studied respectively.The main contents include the following points.details are as follow:1.Better conversion of CO2 is achieved by the combination of metal electrode and semiconductor thin films responsive to visible light.First,the deposition of p-type and n-type Cu2O thin films onto a Cu substrate is successfully achieved.Then,the prepared Cu/Cu2O samples are used for catalytic reduction of CO2 in photoelectrochemical systems in comparison with that in photochemical and electrochemical.systems.The results show that CH4 and C2H4 are the major hydrocarbon gas products,and the prepared Cu/Cu2O samples have much higher selectivity for C2H4 formation compared with the pure Cu electrode.The best yield for CO2 reduction is obtained in the photoelectrochemical system under visible light.Additionally,CO2 conversion efficiency over the Cu/Cu2O(p-type)electrode is much higher than that over Cu/Cu2O(n-type)with similar morphology.The morphology of Cu2O has an effect on the CO2 reduction activity in the photoelectrochemical system as well.2.Electrodeposition method was used to grow Cl doped Cu2O nanorods on crystalline copper substrates with well-controlled phase and high carrier density.Also,we carefully control Cl doping ratio to enable high performance.The Cl doping not only enhanced the carrier density in Cu2O,but also makes it able to produce O2.In this way,the photo generated holes can be easily transferred to surface and participate in reaction.Substantially,the doped samples exhibited excellent catalytic performance and enhance the stability for CO2 reduction under visible light irradiation.Density functional theory calculations reveal that CO binding energy on Cl doped Cu2O is stronger than that on pure Cu2O,making CH4 as a more favored product than CO.3.The CO2 reduction activity of three Re(Ⅰ)complexes is investigated employing a silicon nanowire photoelectrode to drive catalysis.Nanostructured SiNWs can help stabilized Re(I)complexes in PEC system and attached OH group on Re(Ⅰ)complexes can also enhance its stability as well. |
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