Electrochemically activated intermetallic enriched polymetallic nodules for sustainable oxygen evolution electrocatalysis

Abstract

The development of stable and efficient non-noble-metal electrocatalysts for the oxygen evolution reaction (OER) remains a major challenge due to the intrinsically sluggish four-electron transfer and O-O bond formation kinetics. Herein, we report for the first time a novel OER electrocatalyst derived from natural polymetallic nodules (PMNs). The catalyst was synthesized through a facile co-precipitation strategy followed by calcination and electrochemical activation via cyclic voltammetry (CV). The resulting material, denoted as CV-activated PMNs on a nickel substrate (NS), exhibits a hierarchically textured nanostructure that enhances electronic conductivity and exposes abundant catalytic sites, thereby facilitating efficient OER activity. The catalyst demonstrates excellent performance in alkaline electrolyte, delivering a low overpotential of 193 mV at 10 mA cm- 2 together with a favourable Tafel slope of 56 mV dec- 1. The CV-activated PMNs require a cell voltage of only 1.42 V to achieve 10 mA cm- 2 in 1 M KOH. In addition, the catalyst exhibits remarkable long-term electrochemical durability, highlighting its structural stability during continuous operation. These findings demonstrate that polymetallic nodules can serve as sustainable and earth-abundant precursors for the development of efficient OER electrocatalysts for clean energy conversion technologies.