Structural Evolution of Co-Based Metal Organic Frameworks in Pyrolysis for Synthesis of Core–Shells on Nanosheets: Co@CoO_x@Carbon-rGO Composites for Enhanced Hydrogen Generation Activity

Abstract

In this article, Co-based metal organic frameworks (MOFs) with two shapes were used as pyrolysis precursor to synthesize multilayer core-shells composites loaded on reduced graphene oxide (rGO) sheets. The core-shell structures were obtained by the formation of cores from metal ions and carbon shells from carbonization of ligands. Controllable oxidation of Co cores to CoOx shells generated multilayer core-shell structures anchored onto the surface of rGO sheets. The N-doped composites were obtained by adding poly vinylpyrrolidone. The multilayer core-shells composites exhibited superior catalytic activity toward hydrogen generation compared to their single layer counterparts. By using the N-doped multilayer composites, high hydrogen generation specific rate of 5560 mL min(-1) gCo(-1) was achieved at room temperature. The rGO sheets in composites improved their structure stability. These catalysts exhibited high stability after used five cycling. This synergistic strategy proposes simple, efficient, and versatile blue-prints for the fabrication of rGO composites from MOFs-based precursors.

Metal–Organic Framework Based Catalysts for Hydrogen Evolution

“…There are other Co‐based catalysts derived from ZIF‐67, such as Co@carbon–rGO composite and magnetic carbon sponge (MCS) . They are synthesized for chemocatalytic HER from NaBH 4 .…”

Metal organic frameworks as precursors for the manufacture of advanced catalytic materials

“…Xing et al focused their efforts on the preparation of multilayer core-shell composites from Co-MOFs loaded on reduced graphene oxide (rGO) sheets for hydrogen generation from NaBH 4 . 81 The as-obtained Co-MOF-poly vinylpyrrolidone (PVP)-GO black powder was further heated with a ramp of 5 1C min À1 to 700 1C in N 2 for 1 h yielding Co@N-CG and further heat treated at 200 1C for 24 h in air yielding Co@CoO x @N-carbon-rGO (Co@CoO x @N-CG). Additionally, the authors prepared Co@CoO x @CG, Co@CoO x @N-C and Co@CoO x @C, in the absence of PVP, GO and both of them, respectively.…”

Elaborately assembled core-shell structured metal sulfides as a bifunctional catalyst for highly efficient electrochemical overall water splitting

“…More importantly, MOFs can work as templates to guide the resultant morphology and structure. To date, different morphologies, such as hollow polyhedra [28], nanoframes [29], and multilayer core-shells [30], have been successfully synthesized by using MOFs as templates. Specially, MOF-derived hollow structures draw a lot of attention due to their abundant active sites, fast mass transfer and short electrolyte diffusion pathway.…”