In solutions with different pH valu

In solutions with different pH values, the types of substances adsorbed on the catalyst surface are different. Under acidic conditions, the surface of the catalyst mainly adsorbs hydrogen, and the surface of the catalyst is in a reduced state. The adsorbed H + can promote the further generation of NHQ +; it is not conducive to the formation of NHQ + under neutral and alkaline conditions, which may be due to the increase in pH with the solution NHQ + decomposes on its own, and ammonia is more easily oxidized in the form of nonionic NH :. Under alkaline conditions, the surface of the catalyst mainly adsorbs oxides (such as OH, OH, and Ox-), and the surface is in an oxidized state. These oxides occupy the active center of the catalyst, which competes with nitrate for adsorption, and the higher the pH , The higher the coverage, the nitrate reduction activity decreased significantly. Abdallah R et al. [Oat used a porous copper electrode as the cathode to electrolyze nitrate. The experiment found that most of the reduction products of nitrate in neutral solution were ammonia nitrogen, the selectivity of ammonia nitrogen was up to 96%, and the concentration of ammonia nitrogen in acid solution was significantly reduced, and The current efficiency in neutral solutions is significantly higher than in acidic solutions. Maria Dort-siou et al. [35] studied the reaction rate and product composition of the electrochemical reduction of NO3 by 6 kinds of metal electrodes (Sn, Bi, Ph, Al, Zn, Ir>). Foreground metal electrode. When pH> 4, the main products are Nz, NZO, ammonia and nitrite; when the pH is 0-4, the main products are ammonia and light amine.