In situ reconstruction-regulated Fe-doped Ni(OH)2 for glucose oxidation electrocatalytic-enhanced seawater electrolysis

Abstract

Coupling the glucose electrooxidation reaction (GOR) with seawater electrolysis enables high-efficiency, low-energy-consumption H₂ production while co-producing high-value chemicals. Herein, nickel foam-supported Fe-doped Ni(OH)₂ catalysts (Fe_xNi(OH)₂@NF) were synthesized by a hydrothermal method for GOR-assisted seawater electrolysis. Operando electrochemical impedance spectroscopy and in situ Raman spectroscopy reveal that Fe doping lowers the potential for in situ reconstruction into NiOOH active species and markedly boosts the catalytic activities for GOR. Specifically, Fe_0.15Ni(OH)₂@NF achieves 100 mA cm⁻² at only 1.38 V (vs. the reversible hydrogen electrode, RHE), 210 mV lower than that for OER, greatly reducing energy consumption. An anion exchange membrane (AEM) flow electrolyzer using Fe_0.15Ni(OH)₂@NF as both the anode and cathode maintains high stability after 10 consecutive cycles (∼250 h total operation). This system delivers excellent faradaic efficiencies (FEs), with anode FEs of 73.9 ± 2.2% and 24.7 ± 1.6% for formate and gluconate, respectively, and a cathode H₂ evolution FE as high as 99.2 ± 0.5%. This study provides new insights into designing high-efficiency, low-cost catalysts for biomass-coupled seawater electrolysis, facilitating the industrialization of this sustainable H₂ production technology.