Study On The Application Of ORR And CO₂RR On Non-noble Metal Material Surfaces

Due to environmental pollution,energy shortage and the release of large quantities of greenhouse gases,human’s demand for clean energy has increased greatly.Fuel cells are valued for their high energy density and low pollution emissions.However,compared with hydrogen oxidation reaction,oxygen reduction reaction kinetics is very slow and requires a large number of platinum-based catalysts to drive the reaction.High platinum prices and scarce reserves limit the use of fuel cells.Therefore,there is an urgent need to develop cheaper and more efficient non-noble metal catalysts to drive oxygen reduction reactions,such as transition metal oxides.In addition,electrocatalytic carbon dioxide reduction technology to convert carbon dioxide into valuable chemicals is also an effective means to relieve environmental pressure.In addition to noble metal catalyst,metal nitrocarbon material also has good activity of electrocatalytic carbon dioxide reduction to produce carbon monoxide.In this paper,the ORR process of transition metal oxide surface and the CO₂RR process of diatomic Ni Cu NC material surface are studied by DFT,which provides theoretical support for the experiment.Diatomic f-Ni Cu NC-2 with high CO Faraday efficiency was synthesized.In the electrocatalytic oxygen reduction reaction part,the structure of CoO（111）is modified,and the density functional theory is used to simulate the partially reduced CoO（111）catalyst[CO-CoO（111）].The activity of two Co sites（CO-2,Co-3）at the interface of Co-CoO（111）in catalytic oxygen reduction reaction was studied,and the free energy diagram of the reaction was drawn.When Co-2 was used as the active center,the overpotential of Co-CoO（111）catalyst was as low as 0.34 e V.By analyzing the electronic structure of Co-CoO（111）,it was found that the adsorption energy of the intermediate was optimized by adjusting the electronic structure of the material,resulting in the high electrocatalytic oxygen reduction activity of the material.The Ni Cu NC,Ni NCCu NC,Ni NC and Cu NC models were constructed in the electrocatalytic carbon dioxide reduction reaction,and the electrocatalytic carbon dioxide reduction process was simulated.Both Ni and Cu atoms on the surface of diatomic Ni Cu NC react with intermediates during the reaction and reduce the overpotential.Diatomic Ni Cu NC has the best CO₂RR activity.The effect of the construction of diatomic pairs on the electronic structure of Ni and Cu sites was illustrated by analyzing the electronic structure.In addition,experimental exploration was carried out.The f-Ni Cu NC-x series diatomic catalysts were prepared by formamide method,and the structure characterization and electrochemical test showed that the formation of Ni Cu diatoms.The f-Ni Cu NC-2 has more than 90%CO FE at a wide potential window and nearly 100%CO FE at-0.9V vs.RHE potential.The formation of nickel-copper diatomic pairs is the key factor to improve the catalytic activity of Ni NC,and the nickel-copper nitrogen-carbon diatomic materials have certain application potential in CO₂RR.