Graphyne nanotubes as electrocatalysts for oxygen reduction reaction: the effect of doping elements on the catalytic mechanisms

Bai

2017

Materials

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The influences of diameter and length of the Fe−N4-patched carbon nanotubes (Fe−N4/CNTs) on oxygen reduction reaction (ORR) activity were investigated by density functional theory method using the BLYP/DZP basis set. The results indicate that the stability of the Fe−N4 catalytic site in Fe−N4/CNTs will be enhanced with a larger tube diameter, but reduced with shorter tube length. A tube with too small a diameter makes a Fe−N4 site unstable in acid medium since Fe−N and C−N bonds must be significantly bent at smaller diameters due to hoop strain. The adsorption energy of the ORR intermediates, especially of the OH group, becomes weaker with the increase of the tube diameter. The OH adsorption energy of Fe−N4/CNT with the largest tube diameter is close to that on Pt(111) surface, indicating that its catalytic property is similar to Pt. Electronic structure analysis shows that the OH adsorption energy is mainly controlled by the energy levels of Fe 3d orbital. The calculation results uncover that Fe−N4/CNTs with larger tube diameters and shorter lengths will exhibit better ORR activity and stability.

Section: Resultsmentioning

confidence: 99%

DFT Study of the Oxygen Reduction Reaction Activity on Fe−N4-Patched Carbon Nanotubes: The Influence of the Diameter and Length

Bai

2017

Materials

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“…Regarding the cost, the development of robust and effective catalysts without noble metals remains a significant challenge for low‐temperature CO oxidation. Heteroatom‐doped carbon materials (B, N, P, S) have been widely used to boost their reactivity . Experimentally, nitrogen‐doped carbon materials can be prepared by chemical vapor deposition method or a reactive magnetron sputtering method .…”

Section: Introductionmentioning

confidence: 99%

Nitrogen‐doped C₆₀ as a robust catalyst for CO oxidation

Lin

2017

J Comput Chem

The O activation and CO oxidation on nitrogen-doped C N fullerene are investigated using first-principles calculations. The calculations indicate that the C N fullerene is able to activate O molecules resulting in the formation of superoxide species ( O2-) both kinetically and thermodynamically. The active superoxide can further react with CO to form CO via the Eley-Rideal mechanism by passing a stepwise reaction barrier of only 0.20 eV. Ab initio molecular dynamics (AIMD) simulation is carried out to evidence the feasibility of the Eley-Rideal mechanism. In addition, the second CO oxidation takes place with the remaining atomic O without any activation energy barrier. The full catalytic reaction cycles can occur energetically favorable and suggest a two-step Eley-Rideal mechanism for CO oxidation with O catalyzed by the C N fullerene. The catalytic properties of high percentage nitrogen-doped fullerene (C N ) is also examined. This work contributes to designing higher effective carbon-based materials catalysts by a dependable theoretical insight into the catalytic properties of the nitrogen-doped fullerene. © 2017 Wiley Periodicals, Inc.

“…As is well‐known that the relative energy change diagram of each reaction step is an effective method for evaluating the catalytic performance of the oxygen reduction catalyst . The ORR process include 4e − and 2e − reduction pathways, with the final reduction product of the former is H 2 O while the latter is H 2 O 2 .…”

Section: Resultsmentioning

confidence: 99%

Cobalt‐based coordination polymer as high activity electrocatalyst for oxygen reduction reaction: Catalysis by novel active site CoO ₄ N ₂

Lai

2019

Int J Energy Res

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Summary [{Co3(μ3‐OH)(BTB)2(BPE)2}{Co0.5N(C5H5)}] (Co‐CP) as a coordination polymer for catalyzing oxygen reduction reaction (ORR) has recently been reported to exhibit high ORR performance because of its novel structural characteristics. Nevertheless, the detailed mechanism remains far from enough. Herein, first‐principles study of the ORR process of Co(C6H5CO2)2(C5H5N)2 is carried out, which is the constructed model of monomeric unit for this compound. Most interestingly, the calculated results uncover that in the second proton transfer step, the active site contributes to the reaction is not only the Co atom, but also the O and N atoms which are directly bonded to the Co atom that construct a novel active site CoO4N2. Further analysis of the electronic structure demonstrates that the Co, O, and N atoms in the CoO4N2 local structure have participated the electron transfer during the entire ORR process. By analyzing the relative energy changes of whole reaction, it can find that the favorable ORR pathway on the Co(C6H5CO2)2(C5H5N)2 is the 4e− pathway, and the overpotential of ORR on Co(C6H5CO2)2(C5H5N)2 is calculated as 0.43 V, which is consistent with experimental observation and lower than that on the Pt(111). Furthermore, the results of first‐principles molecular dynamics simulations and density of states (DOS) show that Co(C6H5CO2)2(C5H5N)2 presents good stability. And it also possesses high anti‐poisoning ability to some impurity gases such as CO, NO, and NH3.