Synthesis And Studies Of Nickel And Copper Complexes With Photo-or Electrocatalytic Function Of Water Reduction Or Carbon Dioxide Reduction

At present,countries are facing the dual pressure of energy shortage and environmental pollution.Using solar energy or electricity as a driving force for the splitting of water and CO₂reduction reaction,not only can reduce the concentration of CO₂in the air,but also can provide hydrogen and high value-added chemicals or renewable fuels to achieve the conversion or storage between solar energy,electricity and chemical energy,thus to ease the current pressure.Noble metals such as platinum with high catalytic properties are expensive and rare which are not suitable for widespread use.However,with the characteristics of low cost,robust catalytic activity and long catalytic lifetimes,transition metal complexes are very promising in the energy field as molecular catalysts.Works are as following:1.The reaction of Ni Cl₂,K₂(i-mnt)(i-mnt^2-=2,2-dicyanoethylene-1,1-dithiolate)and1-benzyl-4-amino-pyridinium bromide[Bz Py NH₂]Br affords a nickel complex,[Bz Py NH₂]₂[Ni(i-mnt)₂]1.[Bz Py NH₂]₂[Ni(i-mnt)₂]can electrocatalyze hydrogen generation from a neutral buffer with a turnover frequency(TOF)of 556 h^-1at an overpotential(OP)of837.6 m V and a Faradaic efficiency(FE)of 91%.Combining with Cd S nanorods(Cd S NRs)as a photosensitizer,and ascorbic acid(H₂A)as a sacrificial electron donor,complex 1photocatalyzes hydrogen evolution in heterogeneous environments with a turnover number(TON)of 18420 during 60 h irradiation.The highest apparent quantum yield(AQY)is10.21%at 469 nm.2.The reaction of sodium,1,2-benzenedithiol and 2-(chloromethyl)pyridine hydrochloride affords a S₂N₂-type ligand,bptb.The reactions of bptb with Ni X₂·x H₂O(X=Cl,Br)to form two kinds of water-soluble complexes[(bptb)Ni Cl₂]2 and[(bptb)Ni Br₂]3.In neutral phosphate buffer,when the OP is 837.6 m V,the TOF of complexes 2 and 3 are 390 h^-1and 860 h^-1,respectively,and FEs are both up to 98%.Under the three-component photocatalytic system,the TON of complexes 2 and 3 during 80 h irradiation are 15721 and16985,respectively.The results show that the catalytic efficiency for hydrogen evolution of the nickel-based complex with bromine as coordinating groups is more active than chlorine.3.A bidentate O,S-donor ligand N-(4-benzoyl-piperazine-1-carbothioyl)-benzamide(bpcb)is synthesized from the reaction of KSCN with piperazine and benzoyl chloride.Reaction of bpcb with the perchlorate salts M(Cl O₄)₂·6H₂O(M=Cu,Ni)afords complexes Cu(bpcb)₂4 and Ni(bpcb)₂5.As catalysts for hydrogen evolution,after 60 h irradiation,the TON_H2of complexes 4 and 5 are 8143 and 10390,respectively.As catalysts for CO₂reduction reaction with Ru(bpy)₃Cl₂as a photosensitizer and BIH as a sacrificial electron donor,the TON_COof complexes 4 and 5 are 1795 and 1395 after 22 h irradiation at 469 nm,with selectivity 55%and 87%,respectively.The TON_COof complex 4 could reach 3486 after 28 h irradiation.The experimental results indicate that the molecular catalyst with nickel as the central metal has higher photocatalytic hydrogen production activity than copper,and they both have good photocatalytic activity for CO₂reduction.