Design,Synthesis And Studies Of Silver,Copper,Nickel,Iron And Cobalt Complexes With Electrocatalytic Or Photocatalytic Function For Hydrogen Production

With the development of economy,energy crisis and environmental problems have become increasingly prominent.It is urgent to find clean and renewable energy.Hydrogen energy is favored by scientists because of its high calorific value and no pollution.Hydrogen mainly exists in water,and water splitting is the most commonly used method to produce hydrogen.However,much energy is needed in water splitting.Inspired by the natural hydrogenase catalyzing proton reduction to hydrogen in organisms,people simulate the structure of hydrogenase to synthesize molecular catalysts to reduce energy consumption in the process of hydrogen production by water splitting.The works are following:1.Synthesis of six kinds of complexes,[Ag₂（L）₂]1、[Cu₂^Ⅱ（L_α）₄]2、[Cu₂^I（L_β）₂]3、[Fe（phen）₃]（PCPP）₂ 4、[Ni（phen）₃]（PCPP）₂ 5和[（bpy）₂Co（NO₃）]×NO₃×2H₂O 62.Electrocatalytic Activity for hydrogen evolution of complexes（1）Silver complex,[Ag₂（L）₂]1A dinuclear silver complex,[Ag₂（L）₂],formed by reaction of the triazenido ligand,1-[（2-carboxyethyl）benzene]3-[benzimidazole]triazene（HL）and AgNO₃ in proportion to 1:1.The electrochemical studies show that under an overpotential of 877.2 mV,the silver complex can catalyze hydrogen generation from a neutral aqueous buffer（pH 6.5）with a turnover frequency（TOF）of 473 h^-1.（2）Copper complexes with different oxidation statesTwo different oxidation states copper complexes[Cu₂^Ⅱ（L_α）₄]2（L_α=1[（2-iodobenzene）]-3-[benzothiazole]triazene）and[Cu₂^Ⅰ（L_β）₂]3（L_β=1,3-bis[（2-bromo）benzene]Triazene）were synthesized from 2-bromoaniline,2-aminobenzothiazole and 2-iodoaniline.Under an overpotential of 837.6 mV,complexes,[Cu₂^Ⅱ（L_α）₄]2 and[Cu₂^Ⅰ（L_β）₂]3 electrocatalyze hydrogen evolution from neutral buffer（pH 7.0）with a TOF of 502 h^-1 and 582 h^-1,respectively.The results show that the oxidation state of copper has an effect on the electrocatalytic activity,and the copper（I）complex has higher electrocatalytic activity than copper（Ⅱ）complex.（3）Coordinatively saturated complexes with different metalsCoordinatively saturated metal-1,10-phenanthroline（phen）complex,[M^Ⅱ（phen）₃]（PC PP）₂（PCPP=pentacyanopropenide,M=Fe,4;Ni,5）have been designed.Findings show that the coordinatively saturated complexes,[Fe（phen）₃]（PCPP）₂ 4 and[Ni（phen）₃]（PCPP）₂ 5 also exhibit good electrocatalytic activity for hydrogen evolution.In neutral buffer solution,under an overpotential of 838 mV,TOFs of complexes 4 and 5 are 630.1 h^-1 and 673.5 h^-1,respectively.The results indicate that the nickel complex has higher efficiency for hydrogen production than the iron complex.3.Complex with both electrocatalytic and photocatalytic activities for hydrogen evolutionThe cobalt complex,[（bpy）₂Co（NO₃）]×NO₃×2H₂O 6 shows both electrocatalytic and photocatalytic activities for hydrogen generation was synthesized from 2,2-bipyridine（bpy）and Co（NO₃）₂×6H₂O.Under an overpotential of 837.6 mV,complex 6 catalyzes hydrogen evolution from a neutral aqueous buffer（pH 7.0）with a TOF of 403 h^-1.In the three-component photocatalytic system,solution containing 0.10 mM Ru（bpy）₃Cl₂,0.10 M ascorbic acid,and 0.10 mM complex,hydrogen production lasted for 15 hours and TON was about 3000 mol of H₂（mol of cat）^-1.