Design,Synthesis And Catalytic Performance For Hydrogen Production Based On Nickel And Molybdenum Molecular Catalysts

In the context of modern energy challenges,rising global energy demand and energy security issues have spurred research into alternative sustainable energy sources.Hydrogen is an efficient and clean energy source because its raw materials and chemical products are water.Hydrogenases in nature can achieve high-speed and high-efficiency proton reduction on a molecular basis using only iron and nickel in their active sites.However,the active volume of the enzyme is limited by size,and its critical catalytic reaction occurs only at relatively small active sites within some of the larger scaffolds.Therefore,the development of novel hydrogenase active site mimics can solve this problem by allowing the molecular catalyst to achieve greater volume activity by retaining small functional units in the organism or material while discarding excess scaffolds.Based on this,this paper first synthesized and characterized two novel nickel?II?complexes Ni-TPA?TPA=tris[?2-pyridyl?methyl?amine)and Ni-BAPA?BAPA=[bis?6-amino-2-pyridylmethyl?]?2-pyridylmethyl?amine?,attempting to modulate electrocatalytic hydrogen production by direct chemical modification of the introduction of an amino group onto the ligand of the catalyst.The results showed that the catalytic conversion frequency of the complexes Ni-TPA and Ni-BAPA was up to 201 s^-11 and 2425 s^-11 by cyclic voltammetry in acetonitrile solution with p-toluenesulfonic acid as the proton source.This work can reveal the relationship between the structure and electrocatalytic activity of a nickel-based molecular catalyst.Finally,combined with relevant experiments,the catalytic hydrogen production mechanism of these two systems was preliminarily speculated.Molybdenum sulfide represents the most advanced non-platinum electrocatalyst for proton reduction reactions.We then synthesized and characterized four seven-coordinate molybdenum complexes M1?MoO?S₂?₂bpy,bpy=2,2'-bipyridyl?,M2?MoO?S₂?₂Rbpy,Rbpy=4,4'-dimethyl-2,2'-bipyridyl?,M3?MoO?S₂?₂Fbpy,Fbpy=5,5'-dimethyl-2,2'-bipyridyl?,M4?MoO?S₂?₂-Sbpy,Sbpy=4,4'-dimethylformate-2,2'-bipyridyl?,which simulates the molybdenum disulfide active site.Attempted to modulate the MoS₂ edge site by using a ligand by changing the position of the substituent or substituent S-S assisted electrocatalytic hydrogen production performance.It is found that:?1?These four complexes can be used as catalysts for electrocatalytic hydrogen production in organic phase.The maximum conversion frequency of these four complexes was about 80 s^-1and the lowest overpotential was522 mV by cyclic voltammetry using trifluoroacetic acid as the proton source in DMF solution.?2?These four complexes can be used as photocatalytic hydrogen production molecular catalysts under alkaline non-pure water,and pure organic dyes are formed with Eosin Y and TEOA without precious metal components.The homogeneous photoinduced hydrogen production system,the hydrogen production life of the system reaches 10 hours,the maximum number of catalytic cycles of the system is1601.?3?M4 can be used as a homogeneous photoelectrocatalyst for proton reduction under alkaline pure water.The effects of pH,scanning rate and concentration on the hydrogen production rate of the catalyst are studied by linear sweep voltammetry.The catalytic conversion frequency is up to the highest 20.3 s^-1,the overpotential can be as low as 239 mV;M4 can be combined with Eosin Y and TEOA to construct a homogeneous photohydrogen production system in alkaline sodium carbonate aqueous solution.After 9 hours of visible light irradiation,the highest catalysis of the system The number of cycles is 580.Combined with electrochemical tests,the electron transfer reaction and possible hydrogen production mechanism of the system during hydrogen production were analyzed.