In Situ Reconstruction of V‐Doped Ni₂P Pre‐Catalysts with Tunable Electronic Structures for Water Oxidation

Abstract

Nickel-based electrocatalysts are promising candidates for oxygen evolution reaction (OER) but suffer from high activation overpotentials. Herein, in situ structural reconstruction of V-doped Ni 2 P pre-catalyst to form highly active NiV oxyhydroxides for OER is reported, during which the partial dissolution of V creates a disordered Ni structure with an enlarged electrochemical surface area. Operando electrochemical impedance spectroscopy reveals that the synergistic interaction between the Ni hosts and the remaining V dopants can regulate the electronic structure of NiV oxyhydroxides, which leads to enhanced kinetics for the adsorption of *OH and deprotonation of *OOH intermediates. Raman spectroscopy and X-ray absorption spectroscopy further demonstrate that the increased content of active β-NiOOH phase with the disordered Ni active sites contributes to OER activity enhancement. Density functional theory calculations verify that the V dopants facilitate the generation of *O intermediates during OER, which is the rate-determining step for realizing efficient O 2 evolution. Optimization of these properties endows the NiV oxyhydroxide electrode with a low overpotential of 221 mV to deliver a current density of 10 mA cm −2 and excellent stability in the alkaline electrolyte.

Activating lattice oxygen in NiFe-based (oxy)hydroxide for water electrolysis

“…Transition metal oxides or (oxy)hydroxides have been intensively investigated as promising alternative electrocatalysts because of their high catalytic activity, low cost, and good stability. The surface metal sites in these materials are generally considered as the active sites for surface reactions 1 , 2 . Interestingly, recent studies have shown that oxygen in the lattice of metal oxides and (oxy)hydroxides can also participate in surface reactions and may play a critical role in regulating the catalyst activity 3 – 5 .…”

Dynamics and control of active sites in hierarchically nanostructured cobalt phosphide/chalcogenide-based electrocatalysts for water splitting

“…20–25 This reconstruction can proceed via two different routes. Either the as-prepared bulk compounds are fully oxidized into transition metal oxides or (oxy)hydroxides, 19,26–29 or their surfaces can reconstruct into core–shell structures with TMCs and TMPs remaining as core materials. 22,30–33…”

Self-Supporting NiFe Layered Double Hydroxide “Nanoflower” Cluster Anode Electrode for an Efficient Alkaline Anion Exchange Membrane Water Electrolyzer

“…In addition, we evaluated the long-term stability of the NiFe LDHs/Ni fiber electrode through the chronopotentiometry test and studied different current densities (10, 50, 100, 200, 300, and 10 mA cm −2 ) for a total of 60 h (Figure 5e). Figure 5f summarizes the OER performance comparison between NiFe LDHs/Ni fiber electrode and the newly reported non-noble metal-based self-supporting electrodes (see Table 1) [5,6,[40][41][42][43][44][45][46].…”