Preparation Of Hierarchical Porous Zn-N-C Material And Study On Its Electrocatalytic Oxygen Reduction Performance

Transition metal-nitrogen-carbon(M-N-C)materials are considered to be the promising alternatives for noble metal oxygen reduction catalysts due to their high activity and low cost.In this paper,the layered porous Zn-N-C materials were constructed using sodium citrate and pollen-derived biomass carbon as the carbon matrix,and their oxygen reduction activity were explored through material morphology,phase characterization and performance testing.Three-dimensional carbon nanosheets were prepared by high-temperature carbonization of sodium citrate,and added Zn and N sources to prepare Zn-N doped graded porous carbon nanosheet material.By adjusting the process parameters,the Zn-N-3DFC-800 catalyst with the best morphology and performance is obtained.It has good oxygen reduction reaction(ORR)activity in 0.1 M KOH electrolyte,the half-wave potential is 0.81 V(vs.RHE),and the Tafel slope is 80 m V/dec,which is close to Pt/C materials.In addition,the cycle stability test of this material shows that after up to 20,000s,the current density retention rate is about 94%,which is better than 90%of Pt/C,and it has excellent resistance to methanol toxicity.Using rape pollen particles and graphene oxide as the carbon matrix by using simple hydrothermal technology and annealing treatment,the layered porous biomass carbon/graphene nanocomposite materials doped with Zn and N were successfully prepared.The optimized catalyst 10r GO/CPG-N-Zn exhibits better ORR performance in alkaline electrolyte,with a half-wave potential of 0.9 V(vs.RHE),which is higher than0.85 V(vs.RHE)of Pt/C.It also showed good oxygen reduction activity in 0.1 M HCl O₄solution.At the same time,it exhibits excellent electrochemical stability and excellent resistance to methanol poisoning.The doping of Zn and N and the introduction of graphene make the material have a layered porous structure,large specific surface area and high N content,which are the key factors to improve electrocatalytic activity.