• Pt/SnO 2 /Nb 2 O 5 /Nb bifunctional catalyst enables membrane-free hybrid electrolysis. • Oxide support promotes Pt⁰ over Pt(OH)x, enhancing alcohol electrooxidation. • Ethylene glycol yields the highest H 2 production rate: 13.0 µmol h −1 . • Glycerol shows highest electron-to-H 2 selectivity: 95.4% FE. • Ethanol delivers best energy efficiency: 31.2 kWh kg -1 H 2 . This work describes a self-supported Pt/SnO 2 /Nb 2 O 5 /Nb bifunctional electrode, with a cocatalyst synthesized via Plasma Electrolytic Oxidation (PEO) for hydrogen (H 2 ) production through hybrid electrolysis of waste/biomass-derived alcohols. The characterizations obtained by SEM/FEG-EDS highlighted the formation of a coral morphology on the surface of the oxide support, where, in two seconds, the optimization of the PEO parameters minimized the dielectric barrier of the coating developed on the metallic niobium. X-ray photoelectron spectroscopy (XPS) analyses showed that the oxide support favors the formation of the Pt⁰ active phase during solvothermal synthesis. Three-electrode electrochemical characterization demonstrated distinct performances depending on the alcohol used, with a low onset potential (E onset ) of 260 mV for ethanol and a maximum mass activity of 312 mA mgPt −1 for ethylene glycol. The electrode also exhibited an efficient hydrogen evolution reaction (E onset at −38 mV and a Tafel slope of 43.16 mV dec −1 ). In a two-electrode (full cell) configuration without a membrane, ethylene glycol proved to be the most productive (13.0 µmol h −1 of H 2 ), glycerol the most selective (95.4% Faradaic efficiency), and ethanol the most energy-efficient, requiring a specific energy consumption of 31.2 kWh kg −1 of H 2 . In situ infrared spectroscopy (ATR-FTIR) elucidated the specific electrooxidation mechanisms for each compound and revealed that a synergistic effect between Pt and the oxide support mitigates CO ads poisoning at the catalyst active sites. These results offer a versatile approach to biomass/waste valorization, supporting a circular economy and global decarbonization.
Bullmann et al. (Sat,) studied this question.