Fe– and Co–P₄-embedded graphenes as electrocatalysts for the oxygen reduction reaction: theoretical insights

Abstract

Encouraged by the great promise of metal-nitrogen-carbon (M-N-C) materials in replacing Pt for catalyzing the oxygen reduction reaction (ORR), metal-P species were successfully introduced into carbon matrices in experiments and have exhibited high catalytic activity for the ORR. Here, by means of comprehensive density functional theory (DFT) computations, we investigated the origin and the mechanism of the ORR occurring on Fe- and Co-P-embedded graphenes. Our computations have revealed that the Fe- and Co-P4 moiety-embedded graphenes possess good stability and high chemical reactivity for O2 activation, thus facilitating the subsequent ORR steps, and a more efficient 4e pathway in both acidic and alkaline media is more energetically favorable. Furthermore, by analyzing the computed free energy profiles, the Fe-P4 species-embedded graphene is a more efficient electrocatalyst for the ORR in an alkaline medium than the Co-P4 species-embedded graphene. Our DFT computations will be useful for gaining deeper insight into the high activity of metal-P species.

Theoretical Investigation on the Reaction Pathways of the Oxygen Reduction Reaction on Graphene Codoped with Manganese and Phosphorus as a Potential Nonprecious Metal Catalyst

“…For the single O atom, the most favorable adsorption site is on the Mn top site with an adsorption energy of −5.54 eV (Figure d). The adsorption energy of the single O atom is the strongest among the studied single intermediates, which indicates that the O atom has the strongest binding interaction with the MnP 2 ‐Gra surface, similar to that in previous studies (Table ) …”

“…Compared with MnN 4 ‐, FeP 4 ‐, and CoP 4 ‐doped graphene, the adsorption energies on MnP 2 ‐Gra are stronger for O 2 , O, H, OH, OOH, and H 2 O, except for H in FeN 4 (Table ). In addition, edge‐site FeP 2 shows a much stronger adsorption for O 2 and H 2 O (Table ) …”

“…Recently, as new electrocatalysts for the ORR, FeP x and CoP x embedded in a carbon matrix were synthesized and possess a high catalytic activity and durability, which make them promising electrocatalysts for the ORR in FCs . Theoretical studies on FeP 4 ‐ and CoP 4 ‐doped graphenes indicated that FeP 4 ‐doped graphene is a more efficient electrocatalyst for the ORR in an alkaline medium than CoP 4 ‐doped graphene . For FeP 2 ‐doped graphene at the zigzag edge‐site, the hydrogenation of OOH is the most favorable pathway …”

“…[34][35][36] Theoretical studies on FeP 4 -a nd CoP 4 -dopedg raphenes indicated that FeP 4 -doped graphene is am ore efficient electrocatalyst for the ORR in an alkaline mediumt han CoP 4 -doped graphene. [37] For FeP 2 -doped graphene at the zigzag edge-site, the hydrogenation of OOH is the most favorable pathway. [38] Inspired by these studies, in this work we studied the catalytic activity and the ORR mechanism on divacancy graphene codopedw ith MnP x (x = 1-4).…”

Cobalt–Tannin‐Framework‐Derived Amorphous Co−P/Co−N−C on N, P Co‐Doped Porous Carbon with Abundant Active Moieties for Efficient Oxygen Reactions and Water Splitting

“…[11] Furthermore, both experimentala nd theoretical results demonstrated that MÀPc an also act as promising active sites for ORR. [13] Thus, the combination of MÀNa nd MÀPi nt he prepared catalysts can afford excellent trifunctionala ctivities for ORR, HER, and OER. [12] Feng et al,b yu sing DFT,p redicted that FeÀ and CoÀP 4 moieties can activate molecular oxygen through an ideal four-electrons avenue,w hich is beneficial for ORR.…”