Enhanced overall water splitting performance in alkaline solutions using hollow nanocage nickel‑cobalt‑iron layered double hydroxide derived from zeolitic imidazolate framework-67: The synergy of fast etching and metallic ions.

Abstract

The development of highly active, cost-effective, and durable electrocatalysts is critical for efficient water splitting. Layered double hydroxides (LDHs), with their excellent conductivity, large surface area, and three-dimensional (3D) open framework facilitating mass transport and active site accessibility, are ideal candidates. In this work, a ternary nickel‑cobalt‑iron LDH (NiCoFe-LDH) is synthesized via metal ion etching, leveraging synergistic intermetallic electronic interactions to enhance electrocatalytic performance. The as-prepared NiCoFe-LDH exhibits outstanding electrocatalytic performance under alkaline conditions, achieving low overpotentials of 79.60 ± 0.50 mV for the hydrogen evolution reaction (HER) and 373.40 ± 0.50 mV for the oxygen evolution reaction (OER) at 10 mA cm^-2, along with Tafel slopes of 149.61 ± 0.50 and 77.84 ± 0.50 mV dec^-1, respectively. It also demonstrates exceptional stability, with negligible performance degradation after 72 h of rigorous testing. For overall water splitting, NiCoFe-LDH requires only 1.56 ± 0.1 V to deliver 10 mA cm^-2, highlighting its potential for efficient hydrogen production. The incorporation of Fe into NiCo-LDH induces significant electronic structure modifications, including electron delocalization and an upshift in the d-band center, while simultaneously modulating the spin states of Ni/Co ions. These synergistic effects collectively enhance both electrical conductivity and intermediate adsorption capacity. This work highlights cation exchange as an effective strategy for tailoring the electronic properties of layered hydroxides, demonstrating its potential for optimizing material performance in electrocatalysis applications.