Study On Photocatalytic And Electrochemical Hydrogen Evolution By Ethoxycarbonyl Substituted Corrole And Porphyrin Cobalt Complex

Although most of the fuel currently used is fossil fuels,its non-renewable and environmental pollution forces us to find new energy that can replace it.Hydrogen energy has the ideal heat value,good combustion performance,non-toxic,reduce the greenhouse effect and other characteristics,so it is a good alternative to traditional energy options.There are many ways to obtain hydrogen,including hydrogen production from electrolyzed and photolyzed water,non-renewable natural gas and renewable methanol and biomass,but electrolysis of water and photolysis of water seems to be the best one of the ways.The work of this paper is devoted to the design of catalyst molecules for electrocatalytic and photocatalytic hydrogen production.The main contents are as follows:1.The ligands of TECC and TECP were synthesized by the “one-pot two-step” method and the “one-pot” method at room temperature,respectively.Their other cobalt complexes were also synthesized and characterized by UV-Vis spectroscopy,nuclear magnetic resonance(NMR)and mass spectrometry.2.The conversion rate of hydrogenation of complex 1 in DMF with acetic acid as proton source is 2.74 × 10-3 s-1,and in the mixed solution of more proton source(V acetonitrile: Vwater = 2: 3),TOF value increased to 38.79 × 10-3 s-1,Faraday efficiency of about 90%.The results show that the complex 1 has good stability in the process of electrocatalytic hydrogen production by analyzing the EDS experiments of the glassy carbon sheet and the UV-Vis spectrum before and after electrolysis.In combination with the electrochemical experiments and the previously reported literature,it was deduced that the Co(I)active intermediates were formed during the electrocatalytic process.Then Co(I)combined with a proton to form Co(III)-H,Co(III)-H is then combined with a proton to release hydrogen and return to Co(III).In addition,by detecting the UV-Vis spectra with the concentration of complex 1 and mercury poisoning experiments show that complex 1 in the electrocatalytic process for homogeneous catalysis.Under the optimal conditions(the concentration of Ru(bpy)3Cl2 was 0.4 mM,the concentration of ascorbic acid was 0.8 M,the pH value was 4.5,at air atmosphere),when the complex 1(2.28 μM)upon continuous visible irradiation(light-emitting diode lamp,λ = 469 nm)3 hours,the TON value reached 152.3.The conversion rate of hydrogenation of complex 2 in DMF with acetic acid as proton source is 2.0 × 10-3 s-1,and in the mixed solution of more proton source(V acetonitrile: Vwater = 2: 3),TOF value increased to 14.22 × 10-3 s-1,Faraday efficiency of about 87.5%.The results show that the complex 2 has good stability in the process of electrocatalytic hydrogen production by analyzing the EDS experiments of the glassy carbon sheet before and after electrolysis,and the electricity and current on the electrolysis process are very stable.At the same time,we also tested the photocatalytic hydrogen production of complex 2,and the results show that the photocatalytic hydrolysis of complex 2 is not good.