Controllable Preparation Of Non-noble Metal Based Electrocatalyst And Its Application In Zinc-air Battery

The continuous consumption of global fossil fuels has resulted in ecological destruction and global warming,and human beings are facing two major crises:environmental pollution and energy shortage.To mitigate these issues,developing sustainable and efficient energy storage/converting devices has become a pressing need.Zinc-air battery（ZABs）is a promising energy storage device with intrinsic safety and high theoretical specific capacity.However,the slowly kinetic for oxygen reduction reaction（ORR）is the key factor restricting the performance of ZABs.At present,Platinum-based noble metal catalysts are recognized as the benchmark for ORR electrocatalysts,but their large-scale application is restricted by limited stability and expensive price.However,non-noble metal catalysts have poor selectivity and durability for oxygen reduction electrochemistry,which limit their large-scale application.The combination of carbon support and non-noble metal can provide more opportunities for the exposure of active sites for the catalyst due to its high specific surface area and rich pore structure.Therefore,the design and development of carbon materials carrying non noble metal electrocatalysts with excellent oxygen reduction performance has become a research hotspot in the field of materials.In this paper,three kinds of high performance electrocatalysts for oxygen reduction were prepared.The detail contents of this work are as follows:（1）Hollow CeO₂ nanospheres with oxygen vacancies were synthesized by hydrothermal reaction and two-step calcination.In this chapter,the synergistic effect of oxygen vacancy and carbon layer interface on the oxygen reduction reaction of electrocatalyst was studied.Combined with electrocatalysis test and characterization and density functional theory calculation,the internal mechanism of oxygen reduction reaction was explored.In 0.1 M KOH electrolyte,the catalyst has excellent ORR performance with half wave potential of 0.88 V.At the same time,the zinc-air battery assembled by the catalyst also has an excellent power density of 145.1 m W cm^-2.（2）Using MgCl₂ as metal source and glucose as carbon source,precursor was prepared by Sol-Gel method,and then magnesium monatomic catalyst（Mg-SACs）was obtained by further high-temperature carbonization.The half wave potential of 0.93 V in 0.1 M KOH electrolyte is better than that of commercial platinum carbon catalyst.At the same time,the stability and methanol poisoning resistance of Mg-SACs were better than those of commercial platinum carbon catalysts.In order to test the battery performance of Mg-SACs,the zinc-air battery assembled with the catalyst as air cathode has an open circuit voltage of 1.56 V and a power density of 165.7 m W cm^-2.At the same time,the battery charge and discharge stability,after 10 hours charge and discharge performance did not decay.（3）An amorphous nickel based electrocatalyst（Ni-P-NC）was synthesized by coating carbon layer with nano flower like basic nickel carbonate precursor and doping phosphorus.The prepared catalyst has excellent oxygen reduction performance in alkaline electrolyte with half wave potential of 0.94 V.In addition,Ni-P-NC was tested in zinc-air battery,and the maximum power density was 168.4 m W cm^-2.