Green hydrogen production via electrochemical conversion of components from alkaline carbohydrate degradation

Water electrolysis is a promising approach for the sustainable production of hydrogen, however, the unfavorable thermodynamics and sluggish kinetics of oxygen evolution reaction (OER) are associated with high anodic potentials. To lower the required potentials, an effective strategy is proposed to substitute OER with partial oxidation of degradation products of carbohydrate origin from the waste stream of a chemical pulping industry. In this work, two different catalytic materials – PdNi and NiO are investigated comparatively to understand their catalytic performance for the oxidation of carbohydrate alkaline degradation products (CHADs). PdNi can catalyze CHADs with low potential requirements (−0.11 V vs. Hg/HgO at 150 mA cm−2) but is limited to current densities <200 mA cm−2. In contrast, NiO can operate at very high current densities but required relatively higher potentials (0.53 V vs. Hg/HgO at 500 mA cm−2). The performance of this non–noble metal catalyst compares favorably with that of Pd-based catalysts for hydrogen production from CHADs at high conversion rates. This work shows the potential to utilize waste streams from a large-scale process industry for sustainable hydrogen production, and also opens up opportunities to study earth-abundant electrocatalysts to efficiently oxidize biomass-derived substances.