Covalent Organic Framework-Derived Nitrogen-Doped Carbon-Supported Cobalt Oxide Nanoparticles for Synergistic Boosting H2 Evolution from NaBH4

Abstract

Developing nonprecious metal catalysts with fast charge transfer ability, abundant active sites, and easy recovery is of great significance toward sodium borohydride (NaBH4) hydrolysis for hydrogen (H2) production in alkaline solutions. Herein, magnetically separated nitrogen-doped carbon-supported cobalt oxide (CoxOy@NC) nanoparticles were prepared successfully by converting pyrazine-based covalent organic frameworks (COFs). Due to the porous structure and nitrogen-rich characteristics of the precursor, the prepared catalyst CoxOy@NC exhibited good conductivity and charge transfer ability. Cobalt oxide nanoparticles and nitrogen-doped carbon matrix are bonded by the Co–N bond, which makes full use of the conductivity of the substrate and the high activity of the cobalt oxide catalyst. Therefore, CoxOy@NC exhibits an excellent synergistic effect between CoxOy and NC. The H2 generation rate reaches a maximum of 2082.13 mL/min/g from NaBH4 in alkaline solutions. In addition, CoxOy@NC also exhibits good magnetic separation capability, which greatly simplifies the catalyst separation process. Density functional theory (DFT) calculation results indicate that Co2+ is the dominant active component in the heterogeneous catalyst CoxOy@NC. This work broadens new horizons for the development of COFs derivative catalysts for hydrogen production from sodium borohydride hydrolysis.