Regulating the Ni-O bond length by constructing Ni(OH)2/CNTs heterostructure for enhanced nucleophile electrocatalytic oxidation

[Display omitted] The Ni(OH)2/60CNTs heterostructure is constructed by in-situ transformation of NiC2O4/60CNTs. The CNTs increase the valence state of Ni and shorten the Ni-O bond length from 2.03 to 1.98 Å, which facilitates the generation of the active Ni(OH)O intermediates for efficient urea oxidation. •Ni(OH)2/60CNTs heterostructures are fabricated by an in-situ transformation process.•CNTs increase the valence state of Ni and shorten the Ni-O bond length.•The generation of the active Ni(OH)O species is highly promoted.•A hydrogen defect mechanism is consolidated in the urea oxidation process. The electro-driven generation of the active Ni(OH)O species is crucial for the Ni(OH)2 to efficiently drive the nucleophilic oxidation reaction. However, the strategy to facilitate the generation of the Ni(OH)O species is only limited to the construction of the Pt/Ni(OH)2 heterostructures. In this study, carbon nanotubes (CNTs) are employed to reduce the dehydrogenation energy of the Ni(OH)2 by constructing Ni(OH)2/60CNTs heterostructures. The CNTs shorten the Ni-O bond length and increase the valence state of Ni atoms in Ni(OH)2, thus highly promoting the generation of Ni(OH)O. When the Ni(OH)2/60CNTs heterostructure is used for urea oxidation reaction, it displays highly enhanced catalytic activity relative to pure Ni(OH)2, attaining a current density of 10 mA cm−2 at 1.36 V versus reversible hydrogen electrode. This work provides a new strategy for reducing the dehydrogenation energy of the Ni(OH)2 and will inspire more research work on the recognition of the impact of metal–oxygen bond length on NOR activity.