Performance of Surface‐Oxidized Ni₃B, Ni₂B, and NiB₂ Electrocatalysts for Overall Water Splitting

Abstract

The development of efficient and earth-abundant bifunctional electrocatalysts is of great important for energy conversion and storage technologies. Three surface oxidized nickel borides of NiÀ BÀ O@Ni 3 B, NiÀ BÀ O@Ni 2 B and NiÀ BÀ O@NiB 2 electrocatalysts have been prepared and investigated. Surface oxidation, which is inevitable for the bifunctional nickel borides, promotes the activity for the oxygen evolution reaction (OER), but leads to activity degradation for the hydrogen evolution reaction (HER).Meanwhile, boron is found to play a crucial role in the oxidation of nickel, facilitating the formation of an active intermediate for the OER. NiÀ BÀ O@Ni 3 B turns out to be the best bifunctional electrocatalyst. An alkaline electrolyzer constructed using NiÀ BÀ O@Ni 3 B electrodes as both anode and cathode has achieved a current density of 10 mA cm À 2 at 1.58 V for overall water splitting with satisfied durability, rivaling the integrated noble metal electrode.

Recent advances in transition metal-based electrocatalysts for alkaline hydrogen evolution

“…In doping strategies, the universally employed dopants include N, 24,243 P, 244,245 Ni, 246 and the combinations of these single elements. 90,246 Recently, Ji and co-authors prepared N, P-codoped Ni x B y , 94,252,253 Co x B y , 254 Fe x B y , 255 Ru x B y , 256 (Figure 21b).…”

“…It is worth mentioning that amorphous TMBs are inevitably oxidized when exposed to air and water, thus forming oxides/hydroxides on the surface. 94,252,254,257 The presence of oxides/hydroxides can benefit the alkaline HER process. For instance, Chen et al…”

Transition Metal Non‐Oxides as Electrocatalysts: Advantages and Challenges

“…[ 512 ] Such amorphous TMBs exhibit quite poor electrical conductivity, for which postproduction annealing treatment often requires transformation into good electrocatalysts. [ 513–519 ] Moreover, the surface oxidation of TMBs as M–B–O also leads to the exposure of more active sites, facilitating OER activity. [ 513,520 ] The solvent used in the chemical reduction method can also sometimes cause huge differences in the morphologies and compositions of TMBs.…”

Electroless Plating of Transition Metal Boride with High Boron Content as Superior HER Electrocatalyst

“…This structure may benefit the performance of the electrode in several aspects. Firstly, the NiB phase under the oxidation layer can still provide active sites of elemental Ni and B as indicated in previous reports . It is noteworthy that the electron‐enriched elemental Ni 0 in NiB may be more active which probably contribute to its HER performance promotion over nickel with low boron content (e. g. NiB 0.25 ).…”