Coupling pentlandite nanoparticles and dual-doped carbon networks to yield efficient and stable electrocatalysts for acid water oxidation

Abstract

The ability to develop low-cost electrocatalysts with high efficiency and strong stability for acid oxygen evolution reactions (OER) will enable commercial applications of powerful proton exchange membranes (PEM) in water splitting devices. However, this remains challenging because most nonprecious metal-based electrocatalysts suffer from strong corrosion in acid media. Herein, we crafted porous N, S-doped carbon network-immobilized ultrafine pentlandites (i.e., Ni₄Fe₅S₈) nanoparticles (denoted P-NSC/Ni₄Fe₅S₈-1000) by employing rationally designed nanohybrids comprised of liquid polymer-coated binary Prussian blue analogue (PBA) nanoparticles (NPs) as precursors. Afterwards, the P-NSC/Ni₄Fe₅S₈-1000 nanocomposites were exploited as OER electrocatalysts, with a small onset potential of 1.53 V vs. RHE (1 mA cm⁻²) and strong stability in 0.5 M H₂SO₄ solution, outperforming commercial RuO₂ electrocatalysts. As revealed by both experimental results and DFT calculations, there is a synergy effect on the P-NSC/Ni₄Fe₅S₈-1000 for OER: the pyridinic-N, S doped carbon could easily adsorb water, and then the highly active Fe sites of Ni₄Fe₅S₈ NPs could catalyze the absorbed water to oxygen gas. Furthermore, the hierarchically porous nanostructure could promote multiphase transport during acid OER. Therefore, this work, for the first time, highlighted the great potential of pentlandites NPs-based nanocomposites as efficient and stable electrocatalysts for acid OER.