Dual Electronic and Structural Engineering of Fe-CoS2/Laser-Induced Graphene Integrated Electrodes for Oxygen and Hydrogen Evolution

Rational design of high-performance, non-precious bifunctional electrocatalysts for overall water splitting is crucial yet challenging. Herein, a synergistic dual-optimization strategy is proposed, which simultaneously enhances the intrinsic activity at the material level and the mass/charge transfer at the electrode level. Specifically, Fe-doped CoS 2 nanoparticles are in-situ anchored onto a three-dimensional porous laser-induced graphene (LIG) framework, constructing an integrated, binder-free Fe-CoS 2 /LIG electrode. Experimental and spectroscopic characterizations reveal that Fe doping effectively modulates the electronic structure of CoS 2 , inducing lattice contraction and enriching high-valence Co 3+ species, thereby optimizing the adsorption energetics of reaction intermediates. Concurrently, the 3D interconnected LIG substrate serves as a highly conductive and hierarchical gas transport network, which not only prevents the restacking of catalysts but also ensures rapid electrolyte infiltration and efficient bubble detachment. Benefiting from this synergistic design, the Fe-CoS 2 /LIG electrode demonstrates superior electrocatalytic performance for both oxygen and hydrogen evolution reactions individually in 1 M KOH. Remarkably, it achieves low overpotentials of 300 mV for the oxygen evolution reaction and 86 mV for the hydrogen evolution reaction at 10 mA cm -2 , along with rapid reaction kinetics (Tafel slopes of 86 and 94 mV dec -1 , respectively) and robust long-term stability (≥36 h). This work underscores the effectiveness of coupled electronic and structural engineering for designing high-performance, non-precious electrocatalysts.