Comparative Catalytic Activity of Graphene Imperfections in Oxygen Reduction Reaction

Abstract

The oxygen reduction reaction (ORR) is the key operating process that determines the efficiency of energy storage and conversion devices; however, due to sluggish kinetics, it requires a catalyst. In recent years, the trial-and-error approach for the catalyst development has been gradually replaced by the rational design based on theoretical predictions of catalytic activity, which includes the use of so-called descriptors, i.e., certain properties of the catalyst that correlate with the electrocatalytic activity of the material and can be evaluated relatively easily. To assess the applicability of different ORR activity descriptors to a variety of possible catalytic centers of doped graphene (impurity atoms, vacancies, and their combination), here, we consider different graphene imperfections by treating them within the same formalism using the following known descriptors: spin density at the impurity center, molecular orbital descriptor E diff , charge redistribution in graphene caused by the imperfection, and charge redistribution under electrode polarization. To link the catalytic activity to the electronic properties of graphene, we calculated the partial electron density of states (PDOS) related to the reaction site at the Fermi level and local density of states for the reaction center, which are directly related to the electron transfer rate during the ORR. We found their reasonable correlation with PDOS. This fact indicates that descriptors based on the quantum theory are generally the most promising ones for reactivity predictions.

Reactivity Screening of Single Atoms on Modified Graphene Surface: From Formation and Scaling Relations to Catalytic Activity

“…[ 31 ] Nevertheless, new insights on the reactivity of graphene with heteroatoms show that such relations exist and that scaling is actually very good over a wide range of SAs embedded in different graphene‐based surfaces. [ 19,32 ] The parameters of scaling relations presented in Figure 7 are given in Table S10, Supporting Information. Obviously, the slopes of the scaling relations group are around 0.4 and 0.7.…”

“…[35] In contrast, new insights on the reactivity of graphene with heteroatoms show that such relations could exist. [36] The parameters of scaling relations presented in Figure 8 are given in Table S5. Obviously, the slopes of the scaling relations group around 0.4 and 0.7.…”

Origins of Leakage Currents on Electrolyte-Gated Graphene Field-Effect Transistors

“…Theoretical calculations show that these sites are beneficial for the adsorption of the ORR precursors. 42 Moreover, these types of defects have an increased partial density of states (DOS), with a new maximum exactly at the Fermi level. 42 Hence, the DOS-mediated electron-transfer processes are enhanced on these defects.…”

“…This is in agreement with the experimentally established fact that edges of highly oriented pyrolytic graphite show higher electrocatalytic activity than its basal plane. , Structurally, a nonhydrogenated carbon atom of the edge is similar to a carbon atom near a vacancy defect within a lattice. Theoretical calculations show that these sites are beneficial for the adsorption of the ORR precursors . Moreover, these types of defects have an increased partial density of states (DOS), with a new maximum exactly at the Fermi level .…”

Superconcentrated Electrolytes for Aqueous Batteries Based on Alkali Metal Formates and Propionates

“…Quantum-chemical calculations of the ion and water molecule adsorption on graphene were carried out in a similar way as in refs , in the Quantum Espresso package within the generalized gradient approximation by the Perdew–Burke–Ernzerhof (PBE) functional with spin polarization; the maximum energy limit was increased to 500 eV. The integration over the Brillouin zone was performed by the Monkhorst–Pack method of special points with a 0.1 eV smearing width and k -grid density of 5 × 5 × 1 .…”