Tailoring Cobalt-Based Nanomaterials through Doping and Vacancy Engineering for Advanced Hydrogen Evolution Reaction...

Electrolysis of water is an environmentally conscious technique for synthesizing extremely pristine hydrogen, indispensable to accommodating the power and renewable source requirements of modern-day civilization. The real-world implications of the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) suffer from being restricted owing to their sluggish kinetics and dependence on catalysts incorporating noble metals (IrO₂, Pt, and RuO₂). Recently, cobalt-based nanomaterials have garnered significant interest attributable to their distinguished electronic configuration and inexpensiveness, while demonstrating extensive potential applications in catalytic processes. Nonetheless, the poor conductance, inconsistent inherent catalytic activity, and constrained sites of action of cobalt-based catalysts hinder their practical applicability. The review comprehensively examines design methodologies that strengthen the inherent catalytic activity of cobalt-based catalysts, encompassing morphological and framework management, non-metal heteroatom doping, metal heteroatom doping, anion vacancies and cation vacancies, oxygen/selenium vacancies, and interface engineering. A comprehensive evaluation is presented on diverse approaches to synthesizing heteroatom-doped cobalt-based electrocatalysts. Recent developments in cobalt-based nanomaterials for the electrolysis of water are subsequently evaluated, emphasizing the structure property relationship. The primary objective is the manipulation of cobalt oxide electrocatalysts that contain non-metal (anion) and metal (cation) components. Both the constraints and future implications of cobalt-based electrocatalysts are highlighted.