Nitrogen and Phosphorus Dual‐Doped Hierarchical Porous Carbon Foams as Efficient Metal‐Free Electrocatalysts for Oxygen Reduction Reactions

Abstract

Despite tremendous progress in developing doped carbocatalysts for the oxygen reduction reaction (ORR), the ORR activity of current metal-free carbocatalysts is still inferior to that of conventional Pt/C catalysts, especially in acidic media and neutral solution. Moreover, it also remains a challenge to develop an effective and scalable method for the synthesis of metal-free carbocatalysts. Herein, we have developed nitrogen and phosphorus dual-doped hierarchical porous carbon foams (HP-NPCs) as efficient metal-free electrocatalysts for ORR. The HP-NPCs were prepared for the first time by copyrolyzing nitrogen- and phosphorus-containing precursors and poly(vinyl alcohol)/polystyrene (PVA/PS) hydrogel composites as in situ templates. Remarkably, the resulting HP-NPCs possess controllable nitrogen and phosphorus content, high surface area, and a hierarchical interconnected macro-/mesoporous structure. In studying the effects of the HP-NPCs on the ORR, we found that the as-prepared HP-NPC materials exhibited not only excellent catalytic activity for ORR in basic, neutral, and acidic media, but also much better tolerance for methanol oxidation and much higher stability than the commercial, state-of-the-art Pt/C catalysts. Because of all these outstanding features, it is expected that the HP-NPC material will be a very suitable catalyst for next-generation fuel cells and lithium-air batteries. In addition, the novel synthetic method described here might be extended to the preparation of many other kinds of hierarchical porous carbon materials or porous carbon that contains metal oxide for wide applications including energy storage, catalysis, and electrocatalysis.

N, P, and S Codoped Graphene‐Like Carbon Nanosheets for Ultrafast Uranium (VI) Capture with High Capacity

“…According to the survey spectra in Figure 4a, the U(VI)‐adsorbed product maintained all the peaks in the NPS‐GLCs except for two evident peaks at 382.4 and 393.1 eV, which correspond to newly generated U 4f 7/2 and U 4f 5/2 , thereby indicating that a significant number of U(VI) was adsorbed by the NPS‐GLCs 35. The P—O peaks at 133.6 eV and S—O at 168.2 eV in the UO 2 2+ ‐adsorbed NPS‐GLCs increased remarkably as compared to the bare NPS‐GLCs, suggesting that the P and S were oxidized along with UO 2 2+ adsorption 36. We maintained that the UO 2 2+ ions were fixed on the NPS‐GLCs through the strong covalent bonds of P—O—U and S—O—U.…”

1,10-phenanthroline metal complex covalently bonding to poly- (pyrrole-3-carboxylic acid)-coated carbon: An efficient electrocatalyst for oxygen reduction

“…For performance optimization purpose, many reports revealed that the catalytic activity and stability of the catalysts could be improved by employing a porous carbon as the supporting matrix, which can maximize the electroactive surface area of catalysts and improve the rapid transport of other reactants (such as oxygen molecules) and reaction products (such as hydroxide ions) [14]. Carbon materials such as carbon black, carbon nanotubes (CNTs) and graphene have been used as the catalyst supports broadly due to their low costs, porous structures as well as good conductivities [15,16]. Moreover, conducting polymers such as polypyrrole (PPy), polyaniline (PANI) and polythiophene (PTh) have gained considerable attention over the past decades due to their unique chemo-physical properties and have been applied in electrocatalysis and electroanalysis [17,18].…”

B, N-codoped 3D micro-/mesoporous carbon nanofibers web as efficient metal-free catalysts for oxygen reduction

“…(b) and (d), the N1s spectra of both samples are deconvoluted into five N species: graphitic-N (401.3 eV), pyrrolic/pyridone-N (400.7 eV), BeNeC (399.5 eV), pyridinic-N (398.4 eV) and BeN (397.7 eV)[16,36,37]. The content of defect sites is enhanced after NH 3 activation, which agrees well with the Raman results.…”