From Biomass Waste to Green Fuel: Biochar-Based Catalysts for Hydrogen Production

With the increasing demand for energy given by the effects of extreme weathers in the last years, the need to expand the access to renewable energy such as green hydrogen has become a priority in current research. However, one of the main challenges for hydrogen production is the elevated cost of catalysts due to the consumption and lack of availability of rare metals. To reinforce sustainability, biochar, a carbon-rich material has emerged with huge potential. Its properties such as a high surface area and abundant functional groups facilitate catalyst adsorption and the dispersion of active sites, besides the mineral content and surface chemistry tunability, allow the activation and metal impregnation to improve hydrogen production. Considering these characteristics, this paper will highlight all the potential of biochar as a catalyst and catalyst support, the current advances identifying biochar as catalyst in hydrogen production, and the key characteristics that make it adequate in these applications. Finally, the remaining challenges and limitations are described, providing a perspective on future opportunities and research directions.