Urea-doped orange-waste-derived biochar supporting Ni nanoparticles for efficient hydrogen evolution from tetrahydroxydiboron

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This work presents a sustainable hydrogen production process using, for the first time, Ni nanoparticles (Ni NPs) supported on urea-doped orange peel and bagasse biochar (BC-U) derived from tetrahydroxydiboron (THB). Elemental analysis indicated a condensed and stable carbon structure after carbonization, with increased N content after urea doping. FTIR, XRD, SEM, TEM, and XPS confirmed the functional groups, amorphous structure, fragmented morphology, uniform Ni dispersion, and presence of metallic Ni species. TEM revealed Ni NPs with an average size of 4.99 ± 1.22 nm. N 2 adsorption–desorption showed a mesoporous structure and increased surface area after doping, favoring metal dispersion. BC-U-supported Ni NPs exhibited higher H 2 generation efficiency than undoped biochar. Under optimized conditions (2.8 mmol% Ni, 10 mg BC-U, and 60 °C), the activation energy was 39.43 kJ mol −1 . Kinetic isotope effect assays were performed to identify the rate-limiting step. The catalyst remained active over four cycles, demonstrating potential for sustainable H 2 production.