Unravelling the HER Activity of Functionalized Biochar: A Pathway to Cost-Effective Electrocatalysis

Abstract

Abstract The hydrogen evolution reaction (HER) stands at the forefront of green energy technologies, yet its dependence on costly noble metal catalysts often constrains its scalability. As a sustainable and cost-effective alternative, biochar a carbon-rich material derived from biomass pyrolysis, has emerged as a versatile candidate for HER electrocatalysis. This review comprehensively explores the synthesis, physicochemical properties, and catalytic potential of biochar, particularly when functionalized with heteroatoms and transition metals. Emphasis is placed on how structural attributes such as high surface area, tunable porosity, and inherent conductivity enhance HER performance. Various biomass sources, including plant, animal, and industrial waste, are discussed for their influence on biochar's properties. Moreover, heteroatom doping and metal incorporation are critically examined for their role in optimizing electron transfer, increasing active site density, and reducing overpotential. The review concludes with an evaluation of biochar’s environmental benefits, highlighting its alignment with circular economy principles and potential to replace noble metal-based materials in electrocatalytic systems. This synthesis of current advancements establishes biochar as a promising platform for scalable and eco-friendly hydrogen production. Keywords: Biochar, Carbon materials, Electrocatalyst, Sustainable, Eco-friendly, HER.