Highly efficient and non-precious metal electrocatalysts for oxygen evolution reactions (OERs) and oxygen reduction reactions (ORRs) are at the heart of key renewable-energy technologies. Nevertheless, developing highly active bi-functional catalysts at low cost for both OER and ORR still remains a huge challenge. In this paper, Co3O4 nanocrystals embedded in N-doped mesoporous graphitic carbon layer/multiwalled carbon nanotube (MWCNT) hybrids are prepared by a facile carbonization and subsequent oxidation process of MWCNT-based metal–organic frameworks (MOFs). As a result, in alkaline media, the hybrid material catalyzes OER with an onset potential of 1.50 V (vs. reversible hydrogen electrode) and an over-potential only of 320 mV to achieve a stable current density of 10 mA cm−2 for at least 25 h. The same hybrids also exhibit similar catalytic activity but superior stability to the commercial 20 wt% Pt/C catalyst for ORR, making it a high-performance cheap bi-catalyst for both OER and ORR. The design concept of nonmetal-doped and precious-metal-free electrocatalysts from MOFs can be extended to fabricate other novel, stable and easy to use catalyst systems for advanced applications.
We have developed a simple and efficient approach for the synthesis of chemically converted graphene sheets via aryne cycloaddition under mild reaction conditions. The resulting highly functionalized and thermally stable aryne-modified graphene sheets can be well dispersed in various solvents.
17 September 2014 in Journal of Materials Chemistry A
A palladium-based catalyst supported on amine-functionalized magnetite nanoparticles was successfully prepared by a facile one-pot template-free method combined with a metal adsorption–reduction procedure. The catalyst was characterized by TEM, XRD, XPS, FT-IR and VSM. The catalyst afforded fast conversions for various aromatic nitro and unsaturated compounds, and with a turn-over frequency (TOF) of 83.33 h−1 under a H2 atmosphere in ethanol, even at room temperature. Furthermore, it was found that the catalyst showed a high activity for the Heck reaction, affording over a 93% yield in all the cases investigated. Interestingly, the novel catalyst could be recovered in a facile manner from the reaction mixture and recycled eight times without any significant loss in activity.
A polyaniline-multiwalled carbon nanotube supported, high performance CoFe 2 O 4 nanoparticle loaded electrocatalyst is synthesized through a novel and simple in situ process under mild conditions.