A Bifunctional Hybrid Electrocatalyst for Oxygen Reduction and Evolution: Cobalt Oxide Nanoparticles Strongly Coupled to B,N‐Decorated Graphene

Abstract

The electrocatalyzed oxygen reduction and evolution reactions (ORR and OER, respectively) are the core components of many energy conversion systems, including water splitting, fuel cells, and metal–air batteries. Rational design of highly efficient non‐noble materials as bifunctional ORR/OER electrocatalysts is of great importance for large‐scale practical applications. A new strongly coupled hybrid material is presented, which comprises CoOx nanoparticles rich in oxygen vacancies grown on B,N‐decorated graphene (CoOx NPs/BNG) and operates as an efficient bifunctional OER/ORR electrocatalyst. Advanced spectroscopic techniques were used to confirm formation of abundant oxygen vacancies and strong Co−N−C bridging bonds within the CoOx NPs/BNG hybrid. Surprisingly, the CoOx NPs/BNG hybrid electrocatalyst is highly efficient for the OER with a low overpotential and Tafel slope, and is active in the ORR with a positive half‐wave potential and high limiting current density in alkaline medium.

Evolution of Zn(II) single atom catalyst sites during the pyrolysis-induced transformation of ZIF-8 to N-doped carbons

“…For the Zn-N-C-600 sample, prepared at a pyrolysis temperature of 600°C, peak A was observed at~399.0 eV and peak B~401.2 eV. We tentatively assign these to pyridinic N and pyrrolic N environments, respectively [36]. On increasing the pyrolysis temperature to 800°C, peak A shifted to a slightly lower energy of 398.8 eV, whilst peak B (and also peak C) remained largely unshifted.…”

Single Atoms and Clusters Based Nanomaterials for Hydrogen Evolution, Oxygen Evolution Reactions, and Full Water Splitting

“…Tong et al synthesized ultrathin NSs of boron and nitrogen‐rich graphene coupled with oxygen deficient CoO x NPs (CoO x NPs/BNG), which showed a low η 10 = 295 mV with ζ = 57 mV dec −1 . The enhanced OER activity was closely related to oxygen defect rich structure of CoO x , which tuned the electronic structure of the material and increased the oxygen affinity of the catalyst . Also, the formation of strong CoNC and CoBN bonds increased the electrical conductivity of the catalyst and facilitated the electron transfer toward OER active Co metal centers.…”

Co‐decorated reduced graphene/titanium nitride composite as an active oxygen reduction reaction catalyst with superior stability

“…43,44 Transition metal oxides, including cobalt oxide, could be used as to attain good ORR activity. However, its poor electrical conductivity and low ion transfer hinder its ability, 45 as well as other factors such as low surface area and agglomeration 46,47 that also limit its activity. To alleviate these problems, metal oxides including cobalt oxide are usually used in combination with highly conductive materials, such as graphene, 48,49 carbon nanotubes, 50,51 and carbon nanofibers.…”