Optimizing seawater electrolysis with electronically tuned Co3O4 -NiOx heterostructures

Abstract

In seawater electrolysis for hydrogen production, the competition between chlorine evolution and oxygen evolution reaction (OER) at the anode limits its hydrogen yield and system stability. To address this, we optimized the anode material by modulating the surface electronic structure of the active sites of Co₃O₄ using atomic layer deposition (ALD) technology. By introducing the atomic layers of NiO_x species, this approach results in the synthesis of a NiO_x@Co₃O₄/Carbon cloth (CC) heterojunction, which serves as an effective oxygen evolution reaction electrocatalyst for high-performance seawater electrolysis. Adjusting the deposition cycles creates unique material interfaces that facilitate the transformation of reaction intermediate. The NiO_x@Co₃O₄/CC heterostructure demonstrates superior catalytic performance over single-phase materials, which is attributed to its unique Ni-O-Co interface, showing low overpotentials of 204 mV in alkaline freshwater and 235 mV in seawater solutions at 10 mA cm⁻², 285 mV in alkaline freshwater and 329 mV in seawater solutions at 100 mA cm⁻². In addition, the incorporation of NiO_x endowed the material with enhanced overall durability and corrosion resistance, reducing Cl-related species adsorption. After 300 h of chronoamperometric testing, the voltage remained stable, indicating its potential as an ideal electrocatalyst for seawater electrolysis under alkaline conditions.