A porous nickel cyclotetraphosphate nanosheet as a new acid-stable electrocatalyst for efficient hydrogen evolution

Abstract

The stability of non-precious metal-based electrocatalysts for the acidic hydrogen evolution reaction (HER) is of great importance. Here, we have used nickel cyclotetraphosphate (Ni₂P₄O₁₂) nanosheet arrays as a HER electrocatalyst for the first time. The Ni₂P₄O₁₂ arrays were obtained through a facile low-temperature phosphorylation process and possess superior HER catalytic activities and stability in acid. The Ni₂P₄O₁₂ delivers a small overpotential of 131.8 mV at −10 mA cm⁻² and a low Tafel slope of 47.8 mV dec⁻¹ in 0.5 M H₂SO₄, comparable to most of the non-precious metal-based catalysts. Importantly, the Ni₂P₄O₁₂ shows a negligible potential change (6.5 mV) over 80 000 s continuous testing in acid. The remarkable catalytic performances of Ni₂P₄O₁₂ are mainly attributed to the inductive effect of P₄O₁₂⁴⁻ and its polymer-like structure, promoting it as a potential acid-stable HER electrocatalyst.