Functional Species Encapsulated in Nitrogen‐Doped Porous Carbon as a Highly Efficient Catalyst for the Oxygen Reduction Reaction

Abstract

The scarcity, high cost, and poor stability of precious metal-based electrocatalysts have stimulated the development of novel non-precious metal catalysts for the oxygen reduction reaction (ORR) for use in fuel cells and metal-air batteries. Here, we fabricated in situ a hybrid material (Co-W-C/N) with functional species (tungsten carbide and cobalt nanoparticles) encapsulated in an N-doped porous carbon framework, through a facile multi-constituent co-assembly method combined with subsequent annealing treatment. The unique structure favors the anchoring active nanoparticles and facilitates mass transfer steps. The homogenously distributed carbide nanoparticles and adjacent Co-N-C sites lead to the electrocatalytic synergism for the ORR. The existence of Co and W can promote the graphitization of the carbon matrix. Benefiting from its structural and material superiority, the Co-W-C/N electrocatalyst exhibits excellent electrocatalytic activity (with a half-wave potential of 0.774 V vs. reversible hydrogen electrode (RHE)), high stability (96.3 % of the initial current remaining after 9000 s of continuous operation), and good immunity against methanol in alkaline media.

Cobalt‐Doped Perovskite‐Type Oxide LaMnO3 as Bifunctional Oxygen Catalysts for Hybrid Lithium–Oxygen Batteries

“…[43,45] Figure 5c shows typical RRDE voltammograms of LaMn 0.7 Co 0.3 O 3 ,w hich were recorded on aC HI 760D electrochemistry workstation in oxygen-saturated 0.1 m KOH at various rotating speeds.F or LaMn 0.7 Co 0.3 O 3 ,t he yield of HO 2 À is extremely low ( % 4.2 %) throughout the entire potential region between 0a nd 1.0 V. The corresponding electron transfer number (n = 3.92) is almost four,w hich suggests that LaMn 0.7 Co 0.3 O 3 possesses ahighly efficient electrocatalytic activity for the ORR and exhibits af our-electron process over the same potential range. [43,45] Figure 5c shows typical RRDE voltammograms of LaMn 0.7 Co 0.3 O 3 ,w hich were recorded on aC HI 760D electrochemistry workstation in oxygen-saturated 0.1 m KOH at various rotating speeds.F or LaMn 0.7 Co 0.3 O 3 ,t he yield of HO 2 À is extremely low ( % 4.2 %) throughout the entire potential region between 0a nd 1.0 V. The corresponding electron transfer number (n = 3.92) is almost four,w hich suggests that LaMn 0.7 Co 0.3 O 3 possesses ahighly efficient electrocatalytic activity for the ORR and exhibits af our-electron process over the same potential range.…”

Co3O4 Nanoparticle-Decorated N-Doped Mesoporous Carbon Nanofibers as an Efficient Catalyst for Oxygen Reduction Reaction

“…In addition, the N2 adsorption/desorption isotherms of Co3O4@NMCF composite and its corresponding pore-size distribution curves are illustrated in Figure 3f. As shown in Figure 3f, type-IV curves with an H1-type hysteresis loop are presented in N2 adsorption/desorption isotherms of the sample, suggesting that Co3O4@NMCF composite has a typical mesoporous structure [27,28]. The pore-size distribution curves (inset of Figure 3f) show a narrow pore-size distribution, centered at ~5 nm.…”

In Situ Synthesis of Ultrathin Graphene‐Like Nanosheets as a Highly Effective Oxygen Catalyst for Zinc−Air Batteries

“…The N 1s spectrum of Fe/GNS-1.5 can be divided into two peaks at 398.5, 401.2 eV, which belong to pyridinic N and graphitic N, respectively (Figure 2e). [32][33][34] The carbon atom adjacent to nitrogen atom is regarded as the ORR active sites because the highly electronegative of N changes the electronic cloud density of adjacent C. [35] It is generally considered that high content of pyridinic N is benefit to ORR. Compared with Fe-NS, the pyridinic N content of Fe/GNS-1.5 is much higher (Figure S2).…”