Controllable Synthesis Of Metal Organophosphonates And Adjustment Of The Oxygen Evolution Reaction Activities Of Their Derivatives

Metal organophosphonate(MOP)materials are formed by the connection of metal ions and organophosphonic acid ligands,which are a branch of metal-organic frameworks(MOFs).Benefiting from the diverse structures,higher thermal and chemical stability,MOPs have important applications in the fields of catalysis,energy conversion and adsorption.MOPs have many merits.Lots of MOPs with different structures can be obtained by adjusting the metal ions and organophosphonic acid ligands.Organophosphonic acid ligands have a strong affinity to many metal ions and can act as P and C source at the same time;Abundant of organophosphonic acid ligands are easily available and can be modified with heteroelements(such as S,N);Thus there is a broad development space to prepare cheap and efficient OER electrocatalysts by using the MOPs as the precursor.Based on the above background,we mainly studied the syntheses of MOPs and their derivatives applications in OER electrocatalysis.This paper mainly contains the following three aspects:1.Flower-like nickel phenylphosphonate precursor(NiPh)was prepared through a hydrothermal method by using the phenylphosphonic acid as the ligand and Ni2+as the metal source.After calcined the NiPh precursor under H2(5%)/Ar atmosphere,a serious of flower-like carbon doped nickel phosphides(Ni2P,Ni2P-Ni12P5sand Ni12P5)were obtained at different calcination temperature.Benefiting from the derived carbon enhanced the conductivity and higher Ni atomic percentage provided more active sites,the sample denoted as NiP/C-850 exhibited the best OER activity.The overpotential was 290 mV to achieve the current density of 10 mA cm-2 and the corresponding Tafel slope was 74 mV*·dec-1 and exhibited excellent stability.2.We prepared a series of layered bimetal organophosphonate materials(NiFePP)through a hydrothermal method by using the ATMP ligands react with Ni2+and Fe3+.The nickel iron phosphate nanoparticles incorporated in N-doped carbon(NiFeP/N-C)nanoflakes material was obtained after calcined the NiFePP precursor.By adjusting the molar ratio of Nit+/Fe3+and the calcination tenperture,when the the molar ratio of Nit+/Fe3+ was 27:3 and the calcination tenperture was 700'C,the prepared NiFeP/N-C-700 nanoplate exhibited excellent OER activity.Benefiting from the derived conductive N-doped carbon and the synergistic effect of bimetal ions,the overpotential of NiFeP/N-C-700 was 290 mV and the corresponding Tafel slope was 74 mV dec-1 at a current density of 10 mA· cm-2 and exhibited excellent stability.Furthermore,we prepared CoFeP/N-C nanoplate materials in the same method and studied their OER activity.3.We choose and design the synthesis of three organophosphonic acid ligandswith different number ofphosphonic acid groups(PADA?BPG?ATMP),and there are one?two and three phosphoric acid groups for PADA?BPG and ATMP,respectively.Several MOPs were obtained by using the organophosphonic acid ligands reaction with Ni2+.After calcined the MOP precursors under air,the sample denoted as PADA-Ni-700 exhibited the best OER activity.The reason was attributed to the low crystallization degree has more internal defects and can provide more active sites during the reaction process.The overpotential was 360 mV to reach a current density of 10 mA cm-2.