Co-CeOx nanoparticles anchored on a nitrogen-doped carbon nanosheet: a synergistic effect for highly efficient hydrolysis of sodium borohydride

Abstract

Hydrolytic dehydrogenation of sodium borohydride (NaBH₄) has been considered as a source of hydrogen for fuel cell applications. In this work, amorphous and electron-rich Co-CeO_x nanoparticles (NPs) with a small size of 4.4 nm anchored on a nitrogen-doped carbon nanosheet (NCNS) have been prepared via a simple and facile chemical reduction method, in which NCNS was obtained by carbonizing a mixture of metal–organic frameworks ZIF-8 and potassium citrate. The as-prepared Co-CeO_x/NCNS catalyst possesses an outstanding catalytic activity for the catalytic hydrolysis of NaBH₄ at room temperature under alkaline conditions, giving a hydrogen generation rate (HGR) value as high as 28 410 mL_H2·min⁻¹·g_Co⁻¹, which is among the highest HGR values reported to date for all catalysts. The kinetics of hydrolytic dehydrogenation of NaBH₄ aqueous solution was investigated in detail. The excellent catalytic activity of Co-CeO_x/NCNS can be owing to the small size and amorphous state of Co-CeO_x NPs, electron-rich properties of Co NPs modulated by the CeO_x promoter, strong synergistic interaction between Co-CeO_x NPs and the NCNS support with a high surface area and abundant defects, and the promotion of NaOH.