Study On Cobalt Based Complex For Photocatalytic CO₂ Reduction

The increasing consumption of non-renewable energy,such as fossil fuels,not only leads to the energy crisis for human beings but also increases the emission of greenhouse gases,mainly carbon dioxide(CO₂)into the atmosphere,which is leading to a series of global climate problems(such as global warming,frequent extreme weather conditions,etc.).Therefore,converting CO₂ to renewable fuels is an ideal solution to achieve"carbon neutrality"and alleviate the energy crisis and environmental problems.Solar energy has the advantages of inexhaustible,inexhaustible and environment-friendly.Therefore,the use of photocatalytic technology to convert CO₂ into valuable fuel has become a very attractive research hotspot.However,due to the diversity of CO₂ reduction products and the existence of H₂O reduction for hydrogen as a competition reaction,the problems that the activity and selectivity of the target product cannot meet the requirements are urge to be solved.Based on this,this paper carries out the research work titled"Study on cobalt based complex for photocatalytic CO₂ reduction".The main work contents and research results are as follows:1)Two kinds of multi-core ring cobalt complexes named K₁₂[Co(PMIDA)]₆(Co₆)and H₆[Co₄(H₂O)₄(HPMIDA)₂(PMIDA)₂)]·2H₂O(Co4)were synthesized through the hydrothermal method to photocatalyze the reduction of CO₂.With[Ru(bpy)₃]²⁺as photosensitizer and triethanolamine(TEOA)as sacrificant,A TOF of 216 h^-1 of Co₆were obtained under the optimal condition.The light-assisted LSV,light-assisted UV-vis curves,steady state photoluminescence spectra and real-time laser flash photolysis experiments were used to confirm the existence of efficient electron transfer between Co₆ and photosensitizer.Moreover,it was found that the catalytic activity of Co₄ was better than that of Co₆ with the same concentration of co-cobalt ion,the maximum TOF of Co₄ reached to 523 h^-1,which proved that there may be a metal-to-metal synergistic effect in the polymetallic complex.2)Ten bimetallic Prussian blue analogues,Mn-Fe?Mn-Co?Fe-Fe?Fe-Co?Co-Fe?Co-Co?Ni-Fe?Ni-Co?Cu-Fe and Cu-Co PBA,were prepared by a classical coprecipitation method.With[Ru(bpy)₃]²⁺as photosensitizer and triethanolamine(TEOA)as sacrificant,as the potimal catalyst,The selectivity and evolution rate for CO can reach up to 96.8%and 20.8?mol h^-1 over 0.5 mg Ni-Co PBA.The structure and morphology were characterized by IR,XRD,SEM,and TEM.The XPS of Ni-Co PBA before and after photocatalytic CO₂RR and its kinetics curve proves its stability.The difference in their activity was determined by electron transfer rate confirmed by electrochemical experiment and spectral characterization.The reason for the difference in their selectivity was explained by the H₂ adsorption and desorption experiment.