Ruthenium-based medium-entropy alloy oxide for hydrogen evolution linked to biomass sucrose upcycling

Abstract

Wasted biomass upcycling is an environmentally friendly approach that contributes to protecting the Earth. Sucrose is an abundant biomass that can be oxidized to high-value-added formic acid (FA) via the sucrose oxidative reaction (SOR). At the cathode, hydrogen is produced via water splitting. Here, the noble metals Ru and Pd are combined to form a medium-entropy alloy oxide (MEAO) Ru_0.5Pd_0.5O₂. The Ru_0.5Pd_0.5O₂ MEAO shows excellent electrochemical performance: the SOR potential is 1.33 V at 10 mA cm⁻², and the HER overpotential is 55 mV at 10 mA cm⁻² and 324 mV at 100 mA cm⁻². It also demonstrated an ultralow onset voltage and cell voltage of 0.95 V at 10 mA cm⁻² in 1 M KOH + 0.1 M sucrose, which is superior to the commercial RuO₂ + Pt/C system. In addition, Ru_0.5Pd_0.5O₂ successfully converts sucrose to FA with a faradaic efficiency (FE) of 97.7% at 1.6 V. This work paves an avenue for biomass upcycling and hydrogen evolution through the use of MEAO catalysts.