A Facile Molecular Approach to Amorphous Nickel Pnictides and Their Reconstruction to Crystalline Potassium‐Intercalated γ‐NiOOH<sub><i>x</i></sub> Enabling High‐Performance Electrocatalytic Water Oxidation and Selective Oxidation of 5‐Hydroxymethylfurfural
Basundhara Dasgupta, J. Niklas Hausmann, Rodrigo Beltrán‐Suito, Shweta Kalra, Konstantin Laun, Ingo Zebger, Matthias Drieß, Prashanth W. Menezes
Abstract
Abstract The low‐temperature molecular precursor approach can be beneficial to conventional solid‐state methods, which require high temperatures and lead to relatively large crystalline particles. Herein, a novel, single‐step, room‐temperature preparation of amorphous nickel pnictide (NiE; EP, As) nanomaterials is reported, starting from NaOCE(dioxane) n and NiBr 2 (thf) 1.5 . During application for the oxygen evolution reaction (OER), the pnictide anions leach, and both materials fully reconstruct into nickel(III/IV) oxide phases (similar to γ‐NiOOH) comprising edge‐sharing (NiO 6 ) layers with intercalated potassium ions and a d ‐spacing of 7.27 Å. Remarkably, the intercalated γ‐NiOOH x phases are nanocrystalline, unlike the amorphous nickel pnictide precatalysts. This unconventional reconstruction is fast and complete, which is ascribed to the amorphous nature of the nanostructured NiE precatalysts. The obtained γ‐NiOOH x can effectively catalyse the OER for 100 h at a high current density (400 mA cm −2 ) and achieves outstandingly high current densities (>600 mA cm −2 ) for the selective, value‐added oxidation of 5‐hydroxymethylfurfural (HMF). The NiP‐derived γ‐NiOOH x shows a higher activity for both processes due to more available active sites. It is anticipated that the herein developed, effective, room‐temperature molecular synthesis of amorphous nickel pnictide nanomaterials can be applied to other functional transition‐metal pnictides.