Synthesis Of 2D Metal-organic Frameworks And Their Applications In Energy Catalysis

Two-dimensional metal-organic frameworks(MOFs)nanosheets have attracted extensive research interests in the field of electrocatalysis due to their abundant coordinatively unsaturated atoms,high electrical conductivity,high porosity,large surface area,and tunable structure.In the past few years,significant progress has been made in the direct application of pristine 2D MOFs nanosheets as efficient electrocatalysts.In this paper,two-dimensional conductive MOFs were synthesized by organic ligands HOB and HHTP,and their structures and electrochemical properties were explored.The main research contents are as follows:(1)2D MOF(metal-organic frameworks)[Co₃(HOB)₂]_n films were prepared based on Langmuir-Blodgett(LB)method combined with layer-by-layer growth technique.Even 3-layer[Co₃(HOB)₂]_n films could realize the lowest H₂O₂ detection limit of 1.05×10^-8 wt%(3.08nmol?L^-1)based on the resultant 2D MOF catalyst.Meanwhile,density functional theory(DFT)calculations revealed that Co²⁺ions of the LB films decreased the energy of[HOOH]transforming into[HO₂]during the H₂O₂ reduction reactions,thus speeding up the decomposition of H₂O₂.(2)Ni-HHTP/CC,Co-HHTP/CC,Cu-HHTP/CC and Fe-HHTP/CC were synthesized on conductive carbon cloth by hydrothermal method and in-situ growth method,in which SEM showed Ni-HHTP/CC/CC,Co-HHTP/CC,Cu-HHTP/CC all showed a fine rod-like structure,while Fe-HHTP/CC had no obvious structure.Secondly,the OER electrochemical test showed that Ni-HHTP/CC had the best electrocatalytic performance.When the current density was 20m A·cm^-2,it had the lowest potential of 1.63 V and an overpotential of 400 m V.While Co-HHTP/CC,Cu-HHTP/CC and Fe-HHTP/CC potentials were 1.65 V,1.69 V and 1.7 V,respectively.(3)Ni-Fe bimetallic conductive Metal-organic frameworks(MOFs)was syntheticed in-situ grown on carbon cloth(Ni Rh-HHTP/CC)via conventional one-step hydrothermal method.The obtained Ni_0.95Rh_0.05-HHTP/CC was characterized by high electrical conductivity,large specific surface area and affluent nanopores,which enabled the Ni_0.95Rh_0.05-HHTP/CC to improve the electron conductivity and deliver more catalytic active sites.Benefitting from the synergistic interaction of bimetallic Ni-Fe sites and nanostructure advantages,Ni_0.95Rh_0.05-HHTP/CC showed the greatly enhanced catalytic activity of a low overpotential of 320 m V at20 m A·cm^-2 towards OER.The density functional theory(DFT)calculations well corroborate that the activity improvement was mainly attributed to Ni O₄-Rh O₄(Rh site),instead of the Ni O₄-Ni O₄ and Ni O₄-Rh O₄(Ni site),indicating that the Rh doping increases the activity of Ni site.This work systematically examined the Ni_0.95Rh_0.05-HHTP/CC in the OER and provided new avenue for designing the next-generation conductive MOFs catalysts.