WO3-based electrodes fabricated by plasma electrolytic oxidation (PEO) for coupled hydrogen production and organic pollutant removal

The integration of green hydrogen production with wastewater treatment is a promising strategy for addressing the dual challenges of clean energy generation and environmental remediation. Herein, we propose an innovative class of noble metal (Pt, Pd, Ru, etc.)-free cathodes based on tungsten trioxide (WO 3 ), fabricated via plasma electrolytic oxidation (PEO) on affordable aluminum substrates. The PEO process produced porous, adherent, and compositionally complex coatings of mixed crystalline/amorphous WO 3 with embedded W 0 , providing low-cost and scalable electrodes for the hydrogen evolution reaction (HER), which is also effective in water containing organic contaminants. The structural and surface analyses establish ed a clear structure property relationship, correlating WO 3 content and PEO-induced morphology with both hydrogen evolution and pollutant degradation efficiency, while the electrochemical characterization revealed that both increased WO 3 loading and Zn–Al layered double hydroxide functionalization improved charge transfer and HER activity. A15W, selected as the best-performing cathode, achieved up to 1 mmol cm −2 H 2 generation in acidic water contaminated with model organic molecules (rhodamine B, gallic acid, and 3,4,5-trimethoxybenzoic acid), promoting at the same time pollutants electrooxidation (40-100% abatement depending on the reaction conditions). These findings highlight the potential WO 3 -based electrodes as promising, low-cost alternatives to Pt for integrated hydrogen production and wastewater treatment. - WO 3 -based cathodes fabricated by Plasma Electrolytic Oxidation. - A15W enabled efficient H 2 production from polluted water under acidic conditions. - Complete pollutant removal and enhanced H 2 generation in SDW.