Application Of Bipyridine Cobalt And Copper Ferrite For Photocatalytic Reduction Of Carbon Dioxide

With the rapid growth of human demand for fossil fuels,environmental and energy issues have become increasingly prominent,artificial photosynthesis catalytic reduction of carbon dioxide generated with hydrocarbon added value is a feasible way to solve the energy and environmental problems by using solar energy.At present,the use of solar energy for photocatalytic reduction of carbon dioxide system and photoelectrocatalytic reduction of carbon dioxide system has made some progress,but there exists some issues,such as low catalytic efficiency,high cost,low rate of utilization of solar energy and environmental unfriendly.In order to achieve large-scale applications,we should focus on the development of high catalytic activity and stability based on non-noble metal catalysts and non-noble metal semiconductors material with visible light response.This is a very challenging task,as a starting point,this paper focuses on two kinds of systems using solar energy for catalytic reduction of carbon dioxide has been carried out.We constructed a homogeneous three-component system with Co?bpy?₂Cl₂/TEOA/Ru?bpy?₃Cl₂ for photocatalytic reduction carbon dioxide.The catalyst Co?bpy?₂Cl₂ used in this system is a simple and easily synthesized non-noble metal catalyst with excellent catalytic activity and stability.Yields of CO and H₂ as high as 62.3 and 69.9?mol were achieved and the turnover numbers?TONs?reached 6230 and 6990,respectively,under visible light irradiation for 4 h.The maximum optical quantum efficiency of the system is 2.04%at 450nm monochromatic wavelength.After long time illumination,the photosensitizer Ru?bpy?₃Cl₂decomposed into[Ru?bpy?₂]²⁺,but the catalyst Co?bpy?₂Cl₂ still maintains high activity in three cycles.According to the results of electrochemical experiments and quenching experiments,we infered that the excited state of Ru?bpy?₃Cl₂ should be quenchend by the catalyst via oxidation quenching,and the corresponding reaction mechanism was deduced.Based on the development of a high-activity and high-stability carbon dioxide reduction catalyst,the catalyst Co?bpy?₂Cl₂ can be further loaded on the photocathode to realize the photoelectrocatalytic reduction of carbon dioxide by solar energy.We assumed that the molecular catalyst Co?bpy?₂Cl₂ and photosensitizer Ru?bpy?₃Cl₂ are attached to the hole transport material NiO by adsorption group PO₄^3+.During the experiment,it was found that the photosensitizer in the excited state undergoes severe electron hole recombination and electrons cannot be effectively transferred to the catalyst.We decided to change.the idea to find suitable semiconductor material.We found that CuFe₂O₄ can not only meet the redox potential of photocatalytic reduction of carbon dioxide,but also have a good response to visible light.Finally,CuFe₂O₄/FTO thin film electrode was prepared by blade-coating method,which is assembled into a photocathode device for photoelectrocatalytic reduction of carbon dioxide.The CuFe₂O₄/FTO photocathode device can realize light-driven catalytic reduction of carbon dioxide and produce liquid products with methanol and ethanol.The prepared CuFe₂O₄/FTO film electrode has a 1.64 eV bandwidth and a strong response to visible light.With the bias voltage of-0.6 V vs.Ag/AgCl reference electrode and 0.5 M KHCO₃ solution,the optical current density of the assembled photocathode devices reaches 120?A/cm^-2 under visible light,and the stability reaches up to 4000 s.The system produced methanol and ethanol.