Advanced carbon supports for CO2 hydrogenation: Biochar and graphene-based materials for the production of CH4, CH3OH and long-chain hydrocarbons

ABSTRACT Carbon-based materials have emerged as promising supports for catalytic CO 2 conversion, offering a combination of sustainability, tunability, and favorable physicochemical properties. Their high surface area, adjustable porosity, and ability to stabilize small metal nanoparticles make them competitive alternatives to conventional oxide supports in CO 2 hydrogenation processes. This review provides an in-depth analysis of carbonaceous supports derived from biomass—particularly biochar— as well as graphene-based materials for the catalytic reduction of CO 2 to methane, methanol, and long-chain hydrocarbons via Fischer–Tropsch synthesis. Special attention is given to the influence of biomass precursor selection, thermochemical conversion pathways, and chemical or physical activation treatments in tailoring the structural and surface chemistry of biochar. These parameters govern metal dispersion, surface basicity, and metal–support interactions, ultimately determining catalytic activity and product selectivity. Graphene and its derivatives are discussed for their exceptional electronic conductivity, tunable defect density, and ability to promote strong metal anchoring, enabling efficient CO 2 activation and hydrogenation. Across different CO 2 -to-X routes, key structure–performance relationships are identified, and the roles of promoters, bimetallic systems, and synthesis strategies in enhancing catalyst stability and resistance to sintering under reaction conditions are critically examined. Despite significant progress, challenges remain, including improving thermal stability, preventing particle encapsulation, and scaling up sustainable carbonaceous supports. The review concludes by outlining future research directions aimed at integrating low-cost biomass-derived carbons and advanced nanostructured carbons into industrially relevant CO 2 utilization technologies, highlighting their potential to support circular carbon strategies and contribute to decarbonized chemical production.