Valorisation of waste eucalyptus biomass for carbon-based electrocatalysts and electrochemical glucose conversion

Biomass-assisted electrochemical hydrogen production via glucose oxidation offers an energy-efficient alternative to conventional water electrolysis while enabling the co-production of value-added chemicals. Herein, we report a sustainable valorisation strategy for waste eucalyptus biomass, in which the biomass is utilised both as a glucose source and as a precursor for carbon-based electrocatalyst supports. Glucose is extracted from eucalyptus wood through microwave-assisted hydrothermal treatment, while the lignin-rich residue is converted into a three-dimensional nitrogen-doped porous carbon framework anchoring bimetallic NiFe nanospheres through carbonization. The optimized Ni 1 Fe 1 –NAC catalyst exhibits a hierarchical micro–meso–macro porous structure, abundant metal–nitrogen coordination sites, and enhanced electrical conductivity, leading to accelerated charge transfer and improved glucose oxidation kinetics. As a result, the catalyst achieves a current density of 50 mA cm −2 at 1.48 V vs. RHE for commercial glucose and 1.51 V vs. RHE for hydrolysate glucose, with a low onset potential of 1.28 V vs. RHE to reach 10 mA cm −2 . Compared with the oxygen evolution reaction, glucose oxidation significantly reduces the anodic potential, demonstrating clear energy-saving benefits for hydrogen production. Product analysis reveals a glucose conversion rate of up to 96% within 7 h, with formic acid as the dominant product. This work demonstrates an integrated, low-cost, and scalable pathway for coupling green hydrogen generation with biomass-to-chemical conversion, advancing circular-economy-oriented hydrogen technologies. • Hydrolysate glucose and lignin residue from waste biomass are valorised for energy and carbon support. • Lignin-rich residue from eucalyptus waste converted to N-doped carbon for Ni x Fe y NAC. • Ni/Fe ratio optimized to 1:1 (Ni 1 Fe 1 -NAC) for best performance. • Ni 1 Fe 1 -NAC reaches 10 mA cm −2 at 1.28 V vs RHE for hydrolysate glucose. • Glucose efficiently converted to formic acid with 96% yield at 1.58 V.