Platinum-decorated biochar from pequi tree bark as a sustainable catalyst for hydrogen production from ammonia borane

Global efforts to mitigate environmental impacts have intensified the demand for cleaner and more sustainable energy systems. Thus, the development of highly efficient and environmentally benign catalysts for hydrogen (H2) production has emerged as a promising strategy. In this work, a high-performance nanocatalyst composed of platinum nanoparticles supported on activated biochar (Pt NPs/AcB) was developed for hydrogen generation via NH3BH3 hydrolysis. The catalytic support was obtained through the valorization of pequi (Caryocar brasiliense) peel, an abundant agricultural residue, using pyrolysis followed by chemical activation with ZnCl2. The activation process yielded a material with remarkable textural properties, including a high specific surface area of 1142.43 m² g⁻¹ and a predominantly mesoporous structure, which is highly favorable for metal nanoparticle dispersion and anchoring. The Pt NPs/AB catalyst exhibited outstanding catalytic activity toward NH3BH3 hydrolysis, achieving a hydrogen generation rate (HGR) of 2982.1 mL min⁻¹ g⁻¹ under optimized conditions (6.5 mmol% Pt, 10 mg of support, 1.00 mL of NH3BH3 solution at 0.648 mol L⁻¹, and 30 °C). Mechanistic investigations revealed a primary kinetic isotope effect (KIE) of 6.74, indicating that cleavage of the O–H bond of water is the rate-determining step of the reaction. In addition, the catalyst demonstrated excellent durability, maintaining approximately 100% efficiency over 30 consecutive reaction cycles. Overall, this work presents a robust and sustainable catalytic system that provides an efficient route for on-demand hydrogen generation while highlighting the potential of residual biomass as a precursor for advanced carbon materials in energy-related applications.