On-site electrocatalytic synthesis of hydrogen peroxide in potassium fertilizer solutions

The two-electron electrochemical oxygen reduction reaction (ORR) affords an appealing alternative for on-site production of hydrogen peroxide (H2O2), which can fulfill the demands of various applications even at low concentrations. Under neutral or near-neutral conditions, the electrolyte environment capable of electrochemically synthesizing H2O2 exhibits diversity and holds vast potential for practical applications; however, the electrocatalytic performance is limited without desirable electrode materials. In this contribution, methoxylated nickel hydroxides were proposed for high-performance on-site H2O2 electrosynthesis in different potassium fertilizer solutions. The methoxylation compared to pristine Ni(OH)2 was demonstrated to optimize the electronic structure with favorable adsorption of reaction intermediates, obviously enhancing the activity and selectivity. In 0.10 M K2SO4 solution, H2O2 production ranged from 28.1 to 153.6 mg h−1 cm−2 at current densities of −50 to −250 mA cm−2, accompanied by Faradaic efficiency values exceeding 88.0 %. An integrated system was devised by combining fertilization, disinfection, and irrigation through the coupling of two-electron ORR with agricultural irrigation, utilizing nutrient solutions as the electrolyte for on-site H2O2 electrosynthesis. These findings afford a promising avenue for the practical application of 2e− ORR in neutral environments.