| With the rapid growth of economy,people use a lot of energy to meet the needs of social development.However,the traditional fossil fuels(coal,oil,natural gas)are lack of resources,environmental pollution and other problems,the development of green energy is the only way for mankind to seek sustainable development.Hydrogen energy has attracted much attention because of its high energy,no pollution and other characteristics.Water splitting is a common method for hydrogen evolution,but the energy of water splitting is high,so it is necessary to add a catalyst to reduce the energy barrier of the reaction.Transition metal complexes have become a hot topic for researchers because of their low cost and high catalytic activity.The works are following:1.Five complexes were designed and synthesized as molecular catalysts:[Ni(mpo)2]1?[Ni(bdt)2]2?[Co(bdt)2]3?[Ni(dpa)2]4?[Co(dpa)2]5,the structure characterization of five complexes were studied.2.Investigations of catalytic behaviors of complexes 1-5 for hydrogen generation:(1)Catalytic behaviors of the nickel complex 1 for hydrogen generation.The nickel complex[Ni(mpo)2]1 was synthesized by reaction of 2-mercaptopyridine N-oxide sodium salt with NiCl2·6H2O according to the ratio of 2:1.In the photocatalytic system containing complex 1,TON was 8294 mol H2(mol cat)-1after 90 hours of illumination.In the electrocatalytic process,complex 1 was electrolyzed for two minutes under the over-potential of 837.6 mV in the mixed phase,the TOF value was 486 h-1.(2)The impact of central metal centers on catalytic behaviors of complexes supported by bdt for hydrogen production.The square planar nickel complex[Ni(bdt)2]2 and cobalt complex[Co(bdt)2]3 were synthesized by reaction of the ligand benzene-1,2-dithiol(bdt)with NiCl2·6H2O and CoCl2·6H2O in proportion to 2:1,respectively.In the photocatalytic system:the TON values of the system containing complexes 2 and 3 were 11454 mol H2(mol cat)-1,10714 mol H2(mol cat)-1 under long-term light,respectively.In electrocatalytic hydrogen production,complexes 2and 3 were electrolyzed in the mixed phase with an over-potential of 837.6 mV for two minutes,and the TOF value were 266 h-1,70 h-1,respectively.The results showed that the catalytic hydrogen production performance of nickel complex was better than that of cobalt complex when the ligand was bdt.Complex 1-3 with square plane structure had good catalytic performance for hydrogen production.(3)The impact of central metal centers on catalytic behaviors of complexes were supported by dpa for hydrogen production.The nickel complex[Ni(dpa)2]4 and cobalt complex[Co(dpa)2]5 were synthesized by reaction of the ligand Pyridine-2,3-dicarboxylic acid(dpa)with NiCl2·6H2O and CoCl2·6H2O in proportion to 2:1,respectively.The TOF values of complexes 4 and 5 were 679.56h-1,418.28h-1 after electrolysis for two minutes in the mixed phase with an overpotential of 837.6mV,respectively.Consistent with the conclusion of electrocatalytic performance of complexes2 and 3,with the same ligand,the electrocatalytic performance of nickel complex was higher than that of cobalt complex.This was because the nickel complex was more active than the cobalt complex and was more likely to form metal hydride intermediate. |
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