Accelerating water dissociation to achieve ampere-level hydrogen peroxide electrosynthesis in brine and seawater

Ampere-level hydrogen peroxide (H2O2) electrosynthesis in brine and seawater via two-electron oxygen reduction reaction (2e− ORR) is promising, but limited by the slow water dissociation and insufficient protons in neutral media. Hence, we design a multifunctional Ni(OH)2 nanoplates anchored on carbon nanotubes (CNTs) as 2e− ORR catalyst towards H2O2 electrosynthesis, where Ni(OH)2 nanoplates accelerate water dissociation and proton transfer, resolving the critical proton shortage for H2O2 formation. Combined with exceptional chloride tolerance and suppressed hydrogen evolution, the catalyst achieves a high H2O2 yield of 141 mol g−1 h−1 (14.1 mmol cm−2 h−1) at 1 A cm−2 and a long operation time over 150 h at 200 mA cm−2 in 1 M NaCl solution with >80% H2O2 selectivity. In natural seawater, it achieves a Faraday efficiency over 70% at 100 mA cm−2. This work enables water purification/disinfection via simultaneous H2O2/active chlorine production, bridging electrosynthesis with environmental remediation.