Ultrathin nickel-cobalt inorganic-organic hydroxide hybrid nanobelts as highly efficient electrocatalysts for oxygen evolution reaction

Abstract

The electronic properties of semiconducting electrocatalysts are of fundamental research interest and of great importance for oxygen evolution reaction (OER) from water splitting. Engineering the band levels is a promising route to design and fabricate nonprecious earth-abundant semiconducting electrocatalysts for OER. Herein, p-type semiconductor electrocatalysts of ultrathin nickel-cobalt inorganic-organic hydroxide hybrid nanobelts [CoₓNi₁₋ₓ(OH)(BzO)·H₂O, x = 0, 0.2, 0.5, 0.8, 1.0, BzO: benzoate] with favorable band structures are proposed. The CoxNi₁₋ₓ(OH)(BzO)·H₂O with the energetically favorable flat band level and well matched p-p junction exhibit remarkable OER performances in alkaline environment. The optimal Co₀.₈Ni₀.₂(OH)(BzO)·H₂O nanobelt electrocatalyst with nearly 4 nm in thickness achieves the superior OER performance, showing earlier onset potential (E(onset): 1.50 V vs RHE), smaller overpotential (η10: 319 mV) as well as significantly enhanced stability compared with those of IrO₂ reference (E(onset): 1.51 V vs RHE and η10: 343 mV) and most previously reported OER electrocatalysts. This electronic engineering strategy would provide a new insight to the fundamental understanding of underlying OER mechanism as well as open a new avenue to rational design of semiconducting electrocatalysts with high performances.