Carbon Nanosheets Containing Discrete Co-N<sub>x</sub>-B<sub>y</sub>-C Active Sites for Efficient Oxygen Electrocatalysis and Rechargeable Zn-Air Batteries.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 29361224.
- Also identified by DOI 10.1021/acsnano.7b08721.
- No licence information is recorded for this record.
- Because redistribution is not established, this page shows the abstract only. Follow the links below for the full text.
Abstract
Structural and compositional engineering of atomic-scaled metal-N-C catalysts is important yet challenging in boosting their performance for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). Here, boron (B)-doped Co-N-C active sites confined in hierarchical porous carbon sheets (denoted as Co-N,B-CSs) were obtained by a soft template self-assembly pyrolysis method. Significantly, the introduced B element gives an electron-deficient site that can activate the electron transfer around the Co-N-C sites, strengthen the interaction with oxygenated species, and thus accelerate reaction kinetics in the 4e<sup>-</sup> processed ORR and OER. As a result, the catalyst showed Pt-like ORR performance with a half-wave potential (E<sub>1/2</sub>) of 0.83 V versus (vs) RHE, a limiting current density of about 5.66 mA cm<sup>-2</sup>, and higher durability (almost no decay after 5000 cycles) than Pt/C catalysts. Moreover, a rechargeable Zn-air battery device comprising this Co-N,B-CSs catalyst shows superior performance with an open-circuit potential of ∼1.4 V, a peak power density of ∼100.4 mW cm<sup>-2</sup>, as well as excellent durability (128 cycles for 14 h of operation). DFT calculations further demonstrated that the coupling of Co-N<sub>x</sub> active sites with B atoms prefers to adsorb an O<sub>2</sub> molecule in side-on mode and accelerates ORR kinetics.