Use of Heteroatom-Doped g-C3N4 Particles as Catalysts for Dehydrogenation of Sodium Borohydride in Methanol

Abstract

Here, graphitic carbon nitride (g-C3N4) was synthesized from melamine, doped with heteroatoms, such as B, S, and P reported using boric acid, sulfur, and phosphorous red as dopants, respectively. The catalytic performances of g-C3N4, and heteroatom-doped g-C3N4 (H@g-C3N4 (H=B, S or P) particles as catalysts in the dehydrogenation of sodium borohydride (NaBH4) in methanol to generate hydrogen (H2) were investigated. The prepared g-C3N4-based structures were used as catalysts for hydrogen (H2) production in the dehydrogenation reaction of sodium borohydride (NaBH4) in methanol. The catalytic performance of H@g-C3N4 (H=B, S or P) structures in the dehydrogenation reaction of sodium borohydride (NaBH4) in methanol was determined to be higher than the catalytic performance of the bare g-C3N4 structure. The hydrogen generation rate (HGR) values were calculated for the reactions catalyzed by B@g-C3N4, P@g-C3N4, and S@g-C3N4 as 609 ± 48, 699 ± 48, and 429 ± 55 mL H2/g of cat.min, respectively, which is only 282 ± 11 mL H2/g of cat.min for the native g-C3N4-catalyzed one. The activation energies (Ea) were found to be relatively low, such as 31.2, 26.9, and 31.2 kJ/mol, for the reactions catalyzed by B@g-C3N4, P@g-C3N4, and S@g-C3N4, respectively. In addition, in the reuse studies, it was concluded that B@g-C3N4, P@g-C3N4, and S@g-C3N4 catalysts can readily complete the reaction with 100% conversion, even in five consecutive uses, and afforded promising potential with more than 80% activity for each use.