Design,Synthesis And Studies Of Iron,Copper,Nickel,Cobalt Complexes With Hydrogen Production Properties

With the energy crisis and environmental problems,forcing people to look for a new type of green energy.Hydrogen has become a hot spot for scientists because of its high combustion heat and no influence on the environment.Hydrogen is mainly obtained through the cleavage of water,and the water need to consume energy in the cracking process,in nature,is mainly hydrogen producing hydrogenase through pyrolysis process of anaerobic microorganisms to complete water,and organisms are demanding conditions,so the structure of scientists dedicated to the simulation of the hydrogenase to synthetic catalyst.In order to reduce the water splitting of hydrogen energy needed.The works in this paper:1?Synthesis and characterizations of seven complexes,[LaFeCl]1?[LbFeCl]2?[CuI3(dppm)3(?3-Cl)2]·[TCMA]3?[(bpy)2Ni(C104)2]4?Co(TCNQ)2 5?[Co2(HL)2(H2O)2](NO3)6?[(bpy)2Co(SCN)(Cl)]7.2?Electrocatalytic studies of the complexes(1)Two iron complexes with different substituent ligands:The electrocatalytic properties of two new complexes with different substituents,namely,1 and 2,were studied in detail.respectively.1 with a turnover frequency(TOF)of 98.5 h-1 at an overpotential(OP)of 941.6 mV(in DMF),and from aqueous buffer solution(pH 7.0)with a TOF of 676.6 h-1 at an OP of 836.6 mV.2 with a TOF of 50.6 h-1 at an OP of 941.6 mV,and from aqueous buffer solution(pH 7.0)with a TOF of 554 h-1 at an OP of 836.6 mV.These results indicate that the electronic properties of the ligands play vital roles in determining the catalytic activities of the iron complexes.(2)Trinuclear copper(I)complex with P ligand:A trinuclear complex,[CuI3(dppm)3(?3-Cl)2]-[TCMA]3 was synthesized by the reaction of CuCl and dppm.This complex also can act as an electrocatalyst for hydrogen production with a TOF of 99.9 h-1 at an overpotential of 941.6 mV.(3)A satutated nickel complex:A six-coordinated nickel(II)complex,[(bpy)2Ni(ClO4)2]4 was formed by the reaction of bpy and Ni(ClO4)2.Surprisingly,this satutated complex also can act as an electrocatalyst.Electrochemical studies show it can electrocatalyze hydrogen generation from acetic acid with a TOF of 152.88 h-1 at an OP of 941.6 mV(in CH3CN),and from aqueous buffer(pH 7.0)with a TOF of 1464 h-1 at an OP of 837.6 mV.This finding enriches the ligand design.(4)A special salt-ion salt:An electrocatalytic system based on the cobalt salt,Co(TCNQ)2 5 can efficiently electrocatalyze hydrogen generation with a TOF of 767 moles h-1 H2 from a neutral buffer solution(pH 7.0)at an OP of 0.638 V.The result suggests that the addition of TCNQ is the key feature for highly catalytic activity of 5.This can be attributed to the introduction of TCNQ ion to cobalt center,stabilizing the low oxidation state of cobalt.3.photocatalytic inverstigation(1)Under photoirradiation with blue light(?max = 469 nm),[Co2(HL)2(H2O)2](NO3)6,together with ascorbic acid and[Ru(bpy)3]Cl2 in a pH 6.0 aqueous solution,with a remarkable TON of 4314 moles h-1.(2)In a pH 5.0 aqueous solution,[(bpy)2Co(SCN)(Cl)]7 possesses high activity with an initial turnover rate of 2.7×103 mol H2/mol catalyst/h at the first 3 h photolysis and this activity is sustained for at least 10 h with a remarkable TON of 1.2×104 moles h-1.