High-Index Faceted Ni₃S₂ Nanosheet Arrays as Highly Active and Ultrastable Electrocatalysts for Water Splitting

TLDR

High‑index faceted Ni₃S₂ nanosheet arrays on nickel foam offer a promising Earth‑abundant alternative to noble‑metal catalysts for electrochemical processes. The study reports a synthetic method to grow high‑index faceted Ni₃S₂ nanosheet arrays on nickel foam. The method achieves in‑situ growth of these arrays directly on the foam substrate. The resulting Ni₃S₂/NF electrocatalyst delivers ~100 % Faradaic yield for both HER and OER, remains stable for over 200 h, and its superior activity stems from synergistic effects of the nanosheet arrays and exposed {2̅10} facets.

Abstract

Elaborate design of highly active and stable catalysts from Earth-abundant elements has great potential to produce materials that can replace the noble-metal-based catalysts commonly used in a range of useful (electro)chemical processes. Here we report, for the first time, a synthetic method that leads to in situ growth of {2̅10} high-index faceted Ni3S2 nanosheet arrays on nickel foam (NF). We show that the resulting material, denoted Ni3S2/NF, can serve as a highly active, binder-free, bifunctional electrocatalyst for both the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER). Ni3S2/NF is found to give ∼100% Faradaic yield toward both HER and OER and to show remarkable catalytic stability (for >200 h). Experimental results and theoretical calculations indicate that Ni3S2/NF's excellent catalytic activity is mainly due to the synergistic catalytic effects produced in it by its nanosheet arrays and exposed {2̅10} high-index facets.