Screening of catalytic oxygen reduction reaction activity of metal-doped graphene by density functional theory

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 to the OH adsorption, it is noticed that all the ∆ E *OH values on all catalysts are far away from that on the Pt(111). As demonstrated by our previous works, the binding energy of ∆ E *OOH , ∆ E *O , or ∆ E *OH alone is not sufficient to predicate ORR activity. Thus, in order to further explore the catalytic activity of the studied C 58 M, the free energy should be calculated and analyzed, as discussed in the following section.…”

Section: Resultsmentioning

confidence: 76%

Exploring the catalytic activity of metal‐fullerene C ₅₈ M (M = Mn, Fe, Co, Ni, and Cu) toward oxygen reduction and CO oxidation by density functional theory

Chang

et al. 2019

Int J Energy Res

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Summary In the present work, the catalytic activity of metal‐fullerene C58M (M = Mn, Fe, Co, Ni, and Cu) toward oxygen reduction reaction (ORR) and CO oxidation has been explored by detailed density functional theory calculations. Firstly, the binding energy of various ORR species (OOH, O, and OH) on C58M and the corresponding adsorption structures are calculated. The results show that the adsorption strength of any ORR species on C58M follows the order of C58Mn > C58Fe > C58Co > C58Ni > C58Cu and C58Co shows the closest binding energy compared with the Pt(111) surface. Further analysis of the free energy change of ORR indicates that C58Co, C58Ni, and C58Fe have different degrees of catalytic activities, with the calculated free energy change of rate‐determining step of −0.70, −0.32, and −0.04 eV, respectively. On the basis of the above results, the C58Co obviously has the highest ORR activity, with a relatively small overpotential of 0.53 V. In addition, the adsorption free energy of OH can be used as a good descriptor for ORR activity due to the nearly linear relationships between ∆G*OOH, ∆G*O, and ∆G*OH. At last, the catalytic property of C58Co toward CO oxidation reaction is also explored. The calculated results show that CO oxidation on C58Co follows LH mechanism and the rate‐determining step is recognized as *CO + *O2 → *OOCO, with the energy change of −0.13 eV.

“…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%

“…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. [41][42][43] 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 . In addition, we can determine the rate-determining step (RDS) of the entire ORR process, where RDS can be defined as the step in which the energy change is the smallest in all reaction steps.…”

Section: Whole Pathways Of Orrmentioning

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.