Design, Synthesis And Electrocatalytic Properties Of Conductive Metal-organic Framework Materials

Conductive metal-organic framework materials(conductive MOFs),a newly developed energy nanomaterials,have attracted more and more attention since the conductive MOFs not only demonstrate the unique conductivity,but well-inherit the advantages of traditional MOFs,such as high specific surface area and adjustable pore structure,which have been widely applied in the fields of capacitors,electrocatalysis and batteries in recent years.2,3,6,7,10,11-hexahydroxytriphenylenebenzene(HHTP)has more sites that can coordinate with metal ions and large?-conjugated structure,facilitating the synthesis of conductive MOFs with orderly porous structure,which then accelerates the transportation rate of the ions and electrons.Therefore,this paper takes the HHTP as organic ligands to synthesize various conductive MOFs,and deeply study their nanostructures and electrocatalytic performances.The main contents are as follows:(1)Conductive MOFs of Ni-HHTP,Co-HHTP,Cu-HHTP containing different metal ions(Ni,Co,Cu)were synthesized by hydrothermal method.Among them,the Ni-HHTP shows good crystallinity and the most regular rod shape with a diameter of tens of nanometers.The electrochemical results demonstrate that,at a current density is 10 m A cm^-2,the Ni-HHTP delivers the smallest OER overpotential of 420 m V,superior to these of Co-HHTP and Cu-HHTP,verifying that the Ni-HHTP has the best OER activity.(2)The Ni Ru-HHTP doped with different precious metal Ru proportions were synthesized by hydrothermal method,and their regular rod morphology was well maintained.Similarly,electrochemical tests of the samples were carried out,and it can be found that the sample of[Ni_5.7Ru_0.3(HHTP)₃(H₂O)_x]_n doped with 5%Ru shows the better ORR and OER properties than the other synthetic samples.For OER test,it has the smallest overpotential(390 m V)when the current density is 10 m A cm^-2.For ORR test,the half-wave potential is 0.68 V.In addition,when the as-prepared[Ni_5.7Ru_0.3(HHTP)₃(H₂O)_x]_n is used as the cathode catalyst for liquid and all-solid zinc-air batteries,all the corresponding primary battery and rechargeable battery show excellent performance and stability.(3)The Ni Fe-HHTP/CC conductive MOFs doped with a small amount of Fe has been well synthesized by using the hydrothermal method.It can be seen from SEM that Ni+5%Fe-HHTP/CC has a good rod morphology and grows regularly.According to the electrochemical OER tests,the Ni+5%Fe-HHTP/CC shows the best OER performance with the smallest overpotential of 310 m V at the current density of 20 m A cm^-2,which is similar to that of commercial Ru O₂ with the same quality loaded on carbon cloth.In addition,DFT calculations were subsequently carried out to further explore the reaction mechanism for the reaction process,and the results show that the Fe dopants can well facilitate the OER kinetics,provding highly robust active sites,which is lined with the results of experimental tests.