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

Abstract

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.