Trace Sulfur‐Doping Boosts NiCo Heterostructured Catalyst for Selective Glycerol‐to‐Formic Acid Electroreforming

ABSTRACT Hydrogen is a clean energy carrier central to sustainable systems, but electrochemical water splitting is limited by the sluggish oxygen evolution reaction (OER) kinetics. Replacing OER with the thermodynamically favorable glycerol oxidation reaction (GOR) reduces energy input while generating hydrogen and valuable byproducts like formic acid. However, achieving high formic acid selectivity and long‐term durability remains challenging due to complex oxidation pathways. Herein, a cost‐effective sulfur‐doped Ni–Co heterostructured catalyst is designed for efficient GOR. The catalyst achieves 93% formic acid selectivity with 95% glycerol conversion at 1.53 V vs RHE, representing a 33% improvement over undoped NiCo. In a flow cell coupling GOR‖HER (hydrogen evolution reaction), the catalyst maintains stable performance during 200 h of continuous operation at 200 mA cm − 2 . Alternating‐current durability tests under fluctuating operating and shutdown conditions further demonstrate excellent robustness. Comprehensive characterizations and theoretical simulations reveal that the heterojunction interface modulates hydroxide and glycerol adsorption configurations, enabling a dual‐site redox‐coupled mechanism in which Ni acts as − OH activator and redox mediator, while Co serves as the primary glycerol adsorption site. This synergistic effect facilitates kinetically favorable formic acid production and highlights a promising strategy for glycerol upcycling integrated with sustainable hydrogen generation.