Alkaline Electrocatalytic Water Oxidation by Fe-Ni Nanostructures on Porous Turbostratic Carbon with Tailorable Metal-Metal Active Sites

Abstract

Metal ensembles on carbon supports enhance electrocatalysis by requiring close metal-metal proximity, but controlling their clustering remains difficult with current synthesis methods. This study presents a one-step high-throughput synthesis using a bottlebrush block copolymer (BBCP) template, dopamine, and metal precursors (Fe and Ni salts), which can generate high metal loadings (4 at%) of bimetallic Fe-Ni nanostructures with a reduced metallic oxidation state. The BBCP template and polymerized dopamine create a porous carbon matrix upon carbonization. Rapid photothermal pyrolysis, a photonic curing technique, carbonizes samples in seconds, creating uniform Fe-Ni active sites with reduced time and low cost. The short time scales of carbonization and metal precursor reduction favor high metal dispersion, small cluster formation, and the reduced metal oxidation state, all crucial for catalyst performance. In oxygen evolution reaction (OER) testing, the Fe-Ni/N-C catalyst showed a 130 mV overpotential at 10  mA/cm2 and a Tafel slope of 40 mV/dec in 1 M KOH. Tailorable Ni-Fe active sites enable high activity and stability, achieving 100  mA/cm2 at 1.75 V in 1 M KOH at 80 °C with an alkaline membrane electrode assembly (MEA). The unique synthesis approach enables rapid, large-scale production of high-performance electrocatalysts with tunable metal-metal sites, advancing sustainable fuel generation.