A Facile “Double‐Catalysts” Approach to Directionally Fabricate Pyridinic NB‐Pair‐Doped Crystal Graphene Nanoribbons/Amorphous Carbon Hybrid Electrocatalysts for Efficient Oxygen Reduction Reaction

Abstract

Carbon material is a promising electrocatalyst for the oxygen reduction reaction (ORR). Doping of heteroatoms, the most widely used modulating strategy, has attracted many efforts in the past decade. Despite all this, the catalytic activity of heteroatoms‐modulated carbon is hard to compare to that of metal‐based electrocatalysts. Here, a “double‐catalysts” (Fe salt, H3BO3) strategy is presented to directionally fabricate porous structure of crystal graphene nanoribbons (GNs)/amorphous carbon doped by pyridinic NB pairs. The porous structure and GNs accelerate ion/mass and electron transport, respectively. The N percentage in pyridinic NB pairs accounts for ≈80% of all N species. The pyridinic NB pair drives the ORR via an almost 4e− transfer pathway with a half‐wave potential (0.812 V vs reversible hydrogen electrode (RHE)) and onset potential (0.876 V vs RHE) in the alkaline solution. The ORR catalytic performance of the as‐prepared carbon catalysts approximates commercial Pt/C and outperforms most prior carbon‐based catalysts. The assembled Zn–air battery exhibits a high peak power density of 94 mW cm−2. Density functional theory simulation reveals that the pyridinic NB pair possesses the highest catalytic activity among all the potential configurations, due to the highest charge density at C active sites neighboring B, which enhances the interaction strength with the intermediates in the p‐band center.

Manipulating the electronic configuration of Fe–N4sites by an electron-withdrawing/donating strategy with improved oxygen electroreduction performance

“…The change of binding energy occurred because these N species (pyrrolic-N and pyridinic-N) with unpaired electrons were inclined to combine with B atoms forming C-B-N structures, so that electrons transfer from B atoms to N atoms with relatively higher electronegativity. 29,30 However, the graphite-N featured high thermal stability and contained no unpaired electrons, thus graphite-N is hard to bond with B atoms. 20 Moreover, the Fe-N binding energy of Fe-SA/BNC exhibited a negative shift to 399.1 eV, manifesting that B-doping might impact the electronic configuration of Fe-N species.…”

Carbon nanotubes anchored onto hollow carbon for efficient oxygen reduction

“…Among these, commercial proton-exchange membrane fuel cells and metal-air batteries are considered as the next generation of clean energy conversion devices due to their high efficiency, environmental protection, and sustainability [1][2][3][4][5][6]. Given that cathodic oxygen reduction reaction (ORR) is highly susceptible to high activation barriers and sluggish kinetics, low-cost and durable catalysts must be urgently developed to improve the intrinsic activity [7,8]. Nanomaterials based on non-noble transition metals (TMs, such as Fe, Co, and Ni) are promising alternatives for ORR because of their similar electronic configuration to platinum [9,10].…”

Constructing Interfacial Boron‐Nitrogen Moieties in Turbostratic Carbon for Electrochemical Hydrogen Peroxide Production

“…[24] In these regards, many attempts on the synthesis of B/N co-doped CMs (CNB) were reported, using fabrication strategies such as bottom-up chemical vapor deposition methods and topdown thermal annealing approaches. [25][26][27][28] However, despite significant progress, the majority of these works have only shown a 4 e À -favored ORR process in alkaline media, [26,[29][30][31] while that for a 2 e À pathway is still poorly understood. Although some theoretical simulations have indicated the possible active sites for 4 e À or 2 e À ORR in CNB materials, [32] direct experimental evidence is still missing to support those claims due to the lack of accurate control on the as-synthesized active moieties.…”