Highly Exposed Active Sites of Fe/N Co‐doped Defect‐rich Graphene as an Efficient Electrocatalyst for Oxygen Reduction Reaction

Abstract

A defect-rich interconnected hierarchical threedimensional Fe and N co-doped graphene has been prepared by a facile synthesis with poly (2,5-benzimidazole) (ABPBI) as nitrogen and carbon sources and CaCO 3 as the template. ABPBI possesses abundant nitrogen, and pyrolysis of ABPBI is helpful to form graphene structure. CaCO 3 and its decomposition products CO 2 can promote the formation of interconnected hierarchical porous three-dimensional graphene, which possesses more defects and exposed active sites. Benefiting from the defective catalysis mechanism, rich defect catalysts are applied as electrode materials to enhance the catalytic performance for oxygen reduction reaction (ORR). Electrochemically, the half-wave potential (E 1/2) of Fe-3D-NG#800 is 0.84 V (vs. RHE), and the accelerated durability tests shows the E 1/2 of Fe-3D-NG#800 shifted by a 21 mV drop after cyclic voltammetry scanning for 5000 cycles. Therefore, Fe-3D-NG#800 has excellent activity and durability than 20 wt % Pt/C.

Fe–N/P-co-Doped Three-Dimensional Graphene Bifunctional Oxygen Electrocatalysts for Rechargeable Zinc–Air Batteries

“…The LSV was used to generate the Koutecky–Levich (K–L) plots (Figure e). It can assess how well a catalyst selects certain catalytic products (H 2 O 2 and H 2 O). ,− 3D Fe–N/P-G has an electron transfer numeration of 3.95 (0.4–0.7 V vs RHE) (Figure f). It is close to the ideal four-electron reaction, which has a great selectivity in the catalytic reduction of oxygen to H 2 O. Additionally, based on RRDE data, Figure g displays the electron transfer number and H 2 O 2 producing rate.…”

“…42 At present, the synthesis of carbon materials by template method has aroused the interest of researchers, and the commonly used template is NaCl. 43,44 Although the process of synthesizing carbon materials with NaCl as the template is relatively simple, the synthesized carbon materials only have mesopores, which leads to the smaller specific surface area of the carbon materials so that the active sites can not be sufficiently exposed, which leads to the lower catalytic activity. To address the above problems, we have prepared phosphorus-doped 3D graphene materials using phytic acid as a phosphorus source and KCl as a template in a simple method in which nitrogen atoms form an active center Fe-Nx structure with iron atoms in the plane.…”

“…Doping of phosphorus atoms can introduce P–C, P–N, and P–O sites in the carbon matrix, and the introduction of phosphorus atoms can create a synergistic effect with the carbon material, thus improving the catalytic performance. − However, doping of phosphorus atoms also has the disadvantages that the active sites cannot be clear and the synergistic effect is not clear . At present, the synthesis of carbon materials by template method has aroused the interest of researchers, and the commonly used template is NaCl. , Although the process of synthesizing carbon materials with NaCl as the template is relatively simple, the synthesized carbon materials only have mesopores, which leads to the smaller specific surface area of the carbon materials so that the active sites can not be sufficiently exposed, which leads to the lower catalytic activity.…”