Transition Metal-based Electrocatalyst Was Used For The Electrocatalytic Transformation Of Nitrogen-containing Species

The nitrogen cycle,as the most basic element cycle of nature,is destroyed because of the excessive use of fossil energy,so it becomes an urgent goal and necessary move to find out the new energy in line with the development strategy.Electro-chemical technology can use green electric energy to convert CO₂,N₂and small molecule inorganic salts into H₂,NO₃^-and urea and other products with added value,which has a very bright application prospect.In this paper,the coupling of nitrogen oxidation reaction（NOR）,nitrate reduction reaction（NO₃^-RR）,nitrogen dioxide and nitrate reduction reaction（CNCRR）reaction in the nitrogen cycle,through the surface structure characterization of transition metal-based oxides and the catalytic activity of nitrogen-containing species:（1）According to the slow dynamics of N₂solubility during NOR,Co Fe Bi nanosheets containing bimetallic sites and boron doping were prepared by electrodeposition and electrooxidation based on the common LDH to explore the NOR reaction.The phase structure,crystal structure and surface morphology of the materials before and after boron doping were characterized and analyzed by instruments such as SEM,TEM and XPS.The corresponding electrochemical properties were measured using the constant potential timing current method,and the products in the electrolyte were quantified by UV for color development analysis.It was found that the boron-doped Co Fe Bi nanosheets showed a great improvement compared to the Co Fe-LDHs ones,with a nitrate ion yield of 535.78μg h^-1cm_cat^-2at1.7 V vs RHE.Through the physical characterization results,the titanium mesh shows that the growing three-dimensional stacked sheet material structure can greatly increase the surface area of the catalyst,and the doping of non-metallic boron elements can effectively inhibit the OER reaction,thus effectively improving the catalytic activity and reaction active site.（2）Cu₂O,which has catalytic activity for NO₃^-RR,was selected as the initial catalyst,the surface of Cu₂O was regulated,and the product of NO₃^-RR was explored.Cu₂O before and after crystal surface regulation was characterized using the instruments described above.The results showed that after crystal surface regulation,the Cu₂O that exposed the two crystal surfaces showed an increased efficiency by 1.2times compared with the samples without crystal surface regulation.The physical characterization results can show that there is a synergy between the two crystal surfaces when the mass transfer and adsorption can reach the optimal ratio,improve the selectivity of ammonia production,and effectively improve the catalytic activity.（3）Using the TiO₂studied in the electrocatalytic C-N coupling reaction as a carrier,heat treatment was performed to introduce an oxygen vacancy defect and then load the Cu single atom,yielding a Cu modified oxygen-enriched Cu SA-TiO₂-Vo.The structural equal characterization of TiO₂before and after surface treatment is consistent with the above for oxygen vacancies using EPR.Performance tests and product analysis were analyzed using the methods described above.Electrochemical tests showed that surface defects treated TiO₂and single atom modification showed good coupling capacity with 4.79%urea Faraday efficiency at 1.2 V and a urea yield of 712.922 mg h^-1g_cat^-1.The results show that the surface defect treatment and surface modification can increase the TiO₂surface area,and can increase the competition of coupling reactions by regulating the reaction intermediates,and effectively enhance the catalytic reactivity.