Research On MOF-derived Oxygen Reduction Electrocatalyst And Its Performance

With the rapid economic development around the world,people areincreasingly worried about energy shortages and climate change.At present,the development of green,efficient and clean energy has become a research area closely followed by the world.Among them,fuel cells and metal-air batteries have shown great application potential as high-efficiency clean energy devices.Oxygen reduction reaction（ORR）catalyst as the electrode material greatly affects the performance and application prospect of the device.However,traditional noble metal platinum-based catalysts have limited their large-scale promotion and application due to issues such as price and output.In this paper,metal organic framework compounds（MOFs）are used as rawmaterials to develop a new type of porous non-noble metal catalysts.The ORR electrochemical performance of electrocatalysts is studied.The related research contents are as follows:（1）Preparation of Co-MOF derived Co-N-C catalyst and study of its oxygen reduction performance.Co-MOF material ZIF-67 was prepared by solvent synthesis method and instantaneous nano-sedimentation method,and ZIF-67 was modified by high molecular polymer polyethyleneimine（PEI）.Co-N-C was successfully prepared by heat treatment（ZIF-67+PEI）.Studies have shown that the addition of PEI can effectively improve the dispersibility of Co atoms.The prepared Co-N-C（ZIF-67+PEI）has an excellent specific surface area of 404 m²/g and an average pore diameter of 7.1nm.Compared with the sample Co-N-C（ZIF-67）prepared without the addition of PEI,Co-N-C（ZIF-67+PEI）as an ORR electrocatalyst exhibits excellent electrochemical performance,with an initial potential of 0.93 V_RHE,on Pt/C catalyst(0.91 V_RHE).At the same time,Co-N-C（ZIF-67+PEI）has excellent methanol resistance and stability.（2）Study on Ti-MOF derived TiO₂/N-C catalyst and its oxygen reduction performance.Zn-MOF materials ZIF-8 and Ti-doped Ti-ZIF-8 were synthesized,and N-C and TiO₂/N-C materials were obtained after heat treatment.Density functional theory（DFT）calculations show that TiO₂ can significantly improve the stability of OOH*,inhibit the generation of hydrogen peroxide,and improve the electrocatalytic activity of ORR.Compared with N-C,in 0.1M KOH solution,the starting potential of TiO₂/N-C can reach 0.96 V_RHE and the half-wave potential is 0.80 V_RHE.At the same time,TiO₂/N-C also showed good stability and resistance to methanol poisoning.（3）Study on Zn-MOF derived ZnS/N-C catalyst and its oxygen reduction performance.Using Zn-MOF material ZIF-8 as the Zn source and ionic liquid trimethylammonium trioxide copolymer as the sulfur source,ZnS/N-C was successfully prepared by chemical vapor deposition.The specific surface area of the prepared ZnS/N-C-1000 can reach 1205 m²/g,and the average pore volume is 9.2 nm and 0.68 cm cm³/g,respectively.As an ORR electrocatalyst,ZnS/N-C-1000 shows good electrochemical performance in both alkaline media（0.1 M KOH）and acid media（0.1M HClO₄）.In the alkaline medium,the wave potential and half-wave potential(0.98V_RHE and 0.87 V_RHE,respectively);in the acid medium,the wave potential and half-wave potential(0.83 V_RHE and 0.71 V_RHE,respectively).In addition,ZnS/N-C-1000shows better protection against methanol toxicity and stability.