Reviving Oxygen Evolution Electrocatalysis of Bulk La–Ni Intermetallics via Gaseous Hydrogen Engineering

Abstract

A hydrogen processing strategy is developed to enable bulk LaNi5 to attain high activity and long‐term stability toward the electrocatalytic oxygen evolution reaction (OER). By a combination of in situ Raman and quasi in situ X‐ray absorption (XAS) spectra, secondary‐electron‐excited scanning transmission electron microscopy (STEM) patterns as well as the Rietveld method and density functional theory (DFT) calculations, it is discovered that hydrogen‐induced lattice distortion, grain refinement, and particle cracks dictate the effective reconstruction of the LaNi5 surface into a porous hetero‐nanoarchitecture composed of uniformly confined active γ‐NiOOH nanocrystals by La(OH)3 layer in the alkaline OER process. This significantly optimizes the charge transfer, structural integrity, active‐site exposure, and adsorption energy toward the reaction intermediates. Benefiting from these merits, the overpotential (322 mV) at 100 mA cm−2 for the hydrogen‐processed OER catalyst deposited on nickel foam is reduced by 104 mV as compared to the original phase. Notably, it exhibits remarkable stability for 10 days at an industrial‐grade current density of more than 560 mA cm−2 in alkaline media.

A copper interface promotes the transformation of nickel hydroxide into high-valent nickel for an efficient oxygen evolution reaction

“…Overall, the large surface area and high content of NiOOH active species make the Ni(OH) 2 /Cu/NF electrode one of the best Ni-based catalysts so far reported (Table S2 †). 38,41,[43][44][45][46][47][48][49] Furthermore, it also shows excellent stability for the OER (Fig. 5d).…”

An abnormal size effect enables ampere-level O2electroreduction to hydrogen peroxide in neutral electrolytes

“…To simplify the simulation process, only two theoretical crystal structures with different thickness (L-and S-ZnO) have been built, which includes hexagonal zinc oxide with supercells of 5 Â 3 Â 1 (for L-ZnO) and 2 Â 3 Â 1 (for S-ZnO), respectively. [28][29][30] As illustrated in Fig. 3a-c To analyze the above results from an electronic perspective, we have calculated the density of states (DOS) as well as the differential charge density for L-and S-ZnO adsorbed by *OOH intermediates.…”

“…To simplify the simulation process, only two theoretical crystal structures with different thickness (L- and S-ZnO) have been built, which includes hexagonal zinc oxide with supercells of 5 × 3 × 1 (for L-ZnO) and 2 × 3 × 1 (for S-ZnO), respectively. 28–30…”

Electrocatalysts for the oxygen evolution reaction: mechanism, innovative strategies, and beyond

“…Thus, non-noble metal catalysts have been developed and progressively improved as feasible substitutes for noble metal catalysts in the past few decades. [21][22][23][24] The tunable d-electrons and empty orbitals of transition metal oxides, phosphides, nitrides, sulfides, selenides, and carbides make them ideal candidates for OER catalysts. However, it is important to note that not all transition metal compounds demonstrate the desired catalytic activity and stability level for the OER.…”