Oxyanions stabilized low-coordinated nickel species for efficient and durable nucleophilic electrooxidation
Xiaokang Liu, Chengxiang Shi, Gong Zhang, Ruijie Gao, Lun Pan, Xiangwen Zhang, Zhen‐Feng Huang, Jinlong Gong, Ji‐Jun Zou
Abstract
Nucleophilic oxidation reactions (NORs) are key for high-value organics in electrosynthesis, but limited by slow dehydrogenation kinetics and competing oxygen evolution reactions (OER). While low-coordinated Ni species exhibit enhanced activity in rate-determining electrochemical deprotonation, they suffer irreversible oxidation with rapid performance degradation. Herein, we develop a class of oxyanion-stabilized low-coordinated Ni catalysts for highly efficient and durable oxidation of diverse nucleophiles including urea, methanol, and biomass-derived 5-hydroxymethylfurfural. Bicarbonate ligands form an electrostatically repulsive microenvironment, suppressing parasitic OER and Ni over-oxidation via dynamic ligand-cation coordination. These mediators form bifunctional channels, linking Ni2-δ/Ni3-δ reversible transition-based deprotonation and nucleophilic H-transfer, boosting dehydrogenation. A prototype catalyst engineered with bicarbonate ligands via electrochemical pre-reduction achieves 500 mA cm−2 at 1.42 V (versus reversible hydrogen electrode) for urea oxidation and sustains stability for 1100 hours at 100 mA cm−2. Scaling to 100 cm2 anion-exchange membrane reactor yields H2 and valorized organics, showing sustainable electrosynthesis potential. Nucleophilic oxidation in electrosynthesis is hindered by slow dehydrogenation and the competing oxygen evolution reaction (OER). Here an oxyanion-stabilized low-coordinated Ni catalyst suppresses OER and Ni over-oxidation, enabling co-production of H2 and valuable organic compounds.