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

Abstract

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.