Preparation And Electrocatalytic Performance Research Of Co-doped Carbon-based Oxygen Reduction Catalysts With Fe And Non-metallic Heteroatoms

Nowadays,the traditional fossil fuels depend for survival are being rapidly consumed,bringing greenhouse effect,acid rain,haze and other environmental problems.For resolving the energy crisis and environmental pollution,much effects have been devoted to develop renewable and clean energy.Fuel cells and metal-air batteries are the most promising clean energy conversion equipment,and their commercial application are one of the effective ways to alleviate the current problems.At present,noble metal and their oxides are the most widely used electrocatalysts.However,owing to their scarcity,high cost and poor stability,it is not suitable for large-scale industrial applications.Transition metal doped carbon-based electrocatalysts have gradually become the main research direction for researchers because of their better stability and anti-methyl alcohol poisoning effect.Developing novel non-noble metal electrocatalysts with low cost and high efficiency for renewable energy technology have become a common opportunity and challenge all over the world.The basic goal of this paper is to study and explore the key scientific problems in the field of electrocatalysis.By regulating the doping mode of transition metals,two kinds of transition metal oxygen reduction catalysts with excellent performance are prepared,and new ideas are provided for the design and preparation of transition metal carbon based electrocatalysts with reasonable structure.The main contents of the study are as follows:1.Preparation of high-performance iron-doped carbon-based oxygen reduction catalysts by mechanical chemistry method.The ZIF-8 precursor containing transition metal Fe and sodium chloride was synthesized by ball milling by one step.After calcination at high temperature,a 3D porous oxygen reduction catalyst with lamellar edge were obtained.The confinement effect of sodium chloride during pyrolized process led to improve the conductivity,and increased pore structure for 3D-SAFe-NC.In 0.1 M HClO4,3D-SAFe-NC catalyst exhibited a half-wave potential of 0.82 V(vs RHE),which was superior to most of non-noble catalysts.This work provided a novel strategy for simplifying the synthesis process of efficient electrocatalysts.This method was also expected to carry out further mass preparation studies.2.Preparation of iron-doped carbon-based oxygen reduction catalysts by supramolecular self-assembly.Based on the simple and environmentally friendly pursuit of the preparation process,the supramolecular formation of melamine and diphenylphosphate was selected as the precursor of carbon materials.The supramolecular contained abundant N,P heteroatoms,which can be doped into carbon substrates by carbonization pyrolysis.Additionally,iron ions under the protection of complexing molecules was in the form of Fe2P nanocrystals doped into the carbon materials.In 0.1 M KOH,NPC-Fe2 catalyst exhibited a half-wave potential of 0.879 V(vs RHE).This method was simple and efficient and can be used in the preparation of large-scale transition metal oxygen reduction catalysts.The maximum power density of zinc-air batteries is up to 134.2 mW/cm2,which was higher than that of commercial Pt/C catalyst 108.1 mW/cm2.