To Prepare High-performance Metal-air Battery Cathode Catalyst With Bean Dregs As Precursor

The problems of energy shortage and environmental pollution are becoming more and more serious.Research on green and efficient energy storage and conversion devices has become a problem that countries around the world need to face and solve urgently.Fuel cells and metal-air batteries are new types of electrical energy storage devices.They have the characteristics of large energy density and superior rate performance.They are widely used in industry and transportation.The oxygen reduction reaction（ORR）and the oxygen evolution reaction（OER）of the electrolytic water anode can play a key role in both fuel cells and metal-air batteries,and both involve a four-electron transfer process,which has a slow kinetic rate and is used in actual industrial production In the realization of large-scale applications,large obstacles have been encountered.At present,the commercial catalysts of ORR and OER are mainly precious metal catalysts（Pt,Pd,Ru O₂,Ir O₂,etc.）.The high price and scarce reserves limit their wide application in industrial fields.Therefore,it is particularly important to develop inexpensive,clean and efficient non-precious metal catalysts.This paper uses bean dregs as a precursor,metal nitrate as a metal source.Around the traditional Chinese halogen-pointing process,metal particles are wrapped in a gel to make a tofu gel.After freeze-drying and carbonization at high temperature,two-dimensional porous carbon nanomaterials were obtained and applied to the cathode catalysis of fuel cells and metal-air batteries,showing excellent electrocatalytic activity.Studies have shown that the good performance of nitrogen-doped porous carbon nanomaterials mainly depends on the following two aspects:First,when biomass carbon materials such as soybean dregs adsorb metal particles,the surface contains oxygen-containing hydroxyl groups（-OH）,carbonyl groups（-C=O）and carboxyl（-COOH）interact with metals through complexation and hydrogen bonding,which improves the hydrophilic properties of biomass carbon materials.Secondly,the porous structure formed during the tofu gel freeze-drying process provided channels for electrolyte diffusion and accelerated the electron transport process.The main research contents of this article include:（1）A method for preparing a two-dimensional porous carbon nanosheet by embedding a transition metal into a carbon nanomaterial and using the nanometal particle as a pore-forming agent was designed and developed.Gels made with traditional Chinese halogen-containing technology can be used to encapsulate metal particles,which can effectively prevent metal agglomeration.The embedding of Ni nanoparticles not only improves the degree of graphitization of carbon materials,but also acts as a pore-forming agent.After the Ni nanoparticles are etched,more holes are left,the specific surface area of the carbon nanomaterial is increased,and the transport of substances in the electrolyte is promoted.The half-wave potential is 0.75 V,which is only 40 m V less than commercial Pt/C.（2）A method for preparing Ni Co-loaded two-dimensional porous carbon nanosheets by gel method was designed and developed.Ni Co nanoparticles anchored on two-dimensional porous carbon nanosheets（Ni Co/N-C）serve as a dual-function catalyst for zinc-air batteries.Ni and Co subtly act as active centers of OER and ORR,respectively,at a current density of 10 m A·cm^-2,Ni Co/N-C exhibits superior OER catalytic performance than commercial Ru O₂ catalysts,and at the same time,exhibits ORR catalytic performance comparable to commercial Pt/C catalysts.Therefore,Ni Co/N-C is a promising zinc-air battery cathode catalyst.（3）A method for preparing two-dimensional porous carbon nanomaterials with N,P co-doped transition metals was designed and developed.First,cobalt doped carbon nanomaterials were prepared using cobalt nitrate as a metal source,and then sodium hypophosphite was used as phosphorus.Source,the introduction of P element,reduction at350 ^oC to obtain porous carbon material carrying Co P particles.Studies have shown that Co P@N-C exhibits superior OER activity compared to commercial Ru O₂ catalysts,and is a potential electrolytic water catalyst.