First principles study of oxygen molecule interaction with the graphitic active sites of a boron-doped pyrolyzed Fe–N–C catalyst

Abstract

We study the adsorption and the dissociation of O molecules on the active sites of a boron-doped pyrolyzed Fe-N-C catalyst using density functional theory. Initially, we determine the possible structure of the FeN active site of the pyrolyzed Fe-N-C catalyst doped with a boron atom by considering the presence of a nitrogen atom as a metal-free site. The most stable configuration of the structure occurs when the boron and nitrogen atoms coalesce with the FeN site forming a complex site. This structure has higher stability compared to the undoped FeN site. The doped FeN possesses the unique ability to adsorb an oxygen molecule in a side-on mode due to the presence of the boron-nitrogen pair acting as a supporting site. One O atom of the O molecule sticks strongly to the top of the iron atom, while the other binds with the boron atom. This O side-on adsorption stretches the O-O bond length by 15%. Furthermore, the examined catalyst surface can dissociate the oxygen molecule easily with only half the energy barrier of the undoped FeN structure.

Two-Electron Electrochemical Reduction of CO2 on B-Doped Ni–N–C Catalysts: A First-Principles Study

“…Structures with the lowest formation energy are those where the B atom is directly bound to the N atom of NiN 4 center, similar to what has been observed in the FeN 4 -G system. 36 We also find that BN substitution lowers the total energy of the system, indicated by a more negative formation energy compared to its corresponding undoped structure, as depicted in Figure 2. For instance, BN substitution on NiN 4 -G lowers the formation energy of the system by 1.25 eV.…”

“…We used the previously obtained most stable structure of interior and edge NiN 4 sites to be doped with boron. In determining the position of boron defect, we followed the procedure outlined by Fajrial et al 36 The framework constitutes a stepwise approach of initially substituting a B atom, followed by a N atom. The procedure is reiterated in Section S3.…”

“…The trend is similar to that reported in the BN-doped FeN 4 -G structure where the localized p-orbitals of the B dopant are actively responsible for facilitating the ORR dissociative mechanism. 36 CO 2 Reduction to CO and HCOOH. In this section, we discuss the electrochemical reduction of CO 2 into CO and HCOOH over the previously obtained undoped and BNdoped NiN 4 SAC structures.…”

“…The configuration of additional boron and nitrogen sites on the SACs was located using a stepwise procedure introduced in our previous work. 36 All of the structures were modeled under the Atomic Simulation Environment (ASE) package 44 and visualized using the Visualization for Electronic and Structural Analysis (VESTA) program. 45 The formation energy (E form ) of each structure was calculated using…”

Mechanisms of oxygen reduction reaction on B doped FeN 4 G and FeN 4 CNT catalysts for proton‐exchange membrane fuel cells

“…Furthermore, they chose the most stable active site configuration, indicating that the active site could reduce the activation energy of oxygen dissociation with DFT calculations. In addition, Fajrial et al 23 reported that the dissociation of O 2 molecule on the boron‐doped FeNC catalyst through density functional theory (DFT). They found that the activation energy of O 2 dissociation on B‐doped FeNC catalyst is half of that on the un‐doped FeN 4 G.…”