N,P Co‐Coordinated Manganese Atoms in Mesoporous Carbon for Electrochemical Oxygen Reduction

Abstract

The increasing interest in fuel cell technology encourages the development of efficient and low‐cost electrocatalysts to replace the Pt based materials for catalyzing the cathodic oxygen reduction reaction (ORR). In the present work, a nitrogen and phosphorus co‐coordinated manganese atom embedded mesoporous carbon composite (MnNPC‐900) is successfully prepared via a polymerization of o‐phenylenediamine followed by calcination at 900 °C. The MnNPC‐900 composite shows a high ORR activity in alkaline media, offering an onset potential of 0.97 V, and a half‐wave potential of 0.84 V (both vs reversible hydrogen electrode) with a loading of 0.4 mg cm−2. This performance not only exceeds its phosphorus‐free counterpart (MnNC‐900), but also is comparable to the Pt/C catalyst under identical measuring conditions. The significantly enhanced ORR performance of MnNPC‐900 can be ascribed to: i) the introduction of phosphorus assists the generation of mesopores during the pyrolysis and endows the MnNPC‐900 composite with large surface area and pore volume, thus facilitating the mass transfer process and increases the number of exposed active sites. ii) The formation of N,P co‐coordinated atomic‐scale Mn sites (MnNxPy), which modifies the electronic configuration of the Mn atoms and thereby boosts the ORR catalytic activity.

Thermodynamically Stable Mesoporous C3N7 and C3N6 with Ordered Structure and Their Excellent Performance for Oxygen Reduction Reaction

“…Although platinumbased materials offer superior catalytic activity in ORR, scare reserve and low methanol tolerance of platinum prompt development of nonprecious alternatives such as transition metal alloys, metal oxides and metal-free compounds. [20][21][22][23][24][25] The ORR activity of g-C 3 N 4 as a metal-free electrocatalyst was first reported by Lyth et al and at the same time, they suggested to mix the g-C 3 N 4 with carbon to overcome sluggish kinetics of the g-C 3 N 4 . [26] The strategy of compositing the g-C 3 N 4 with carbon materials brought a huge improvement in ORR activity of the g-C 3 N 4.…”

“…Electrochemical oxygen reduction reaction (ORR) is a crucial process for renewable energy applications such as fuel cells, metal‐air batteries and solar cells. Although platinum‐based materials offer superior catalytic activity in ORR, scare reserve and low methanol tolerance of platinum prompt development of nonprecious alternatives such as transition metal alloys, metal oxides and metal‐free compounds . The ORR activity of g‐C 3 N 4 as a metal‐free electrocatalyst was first reported by Lyth et al and at the same time, they suggested to mix the g‐C 3 N 4 with carbon to overcome sluggish kinetics of the g‐C 3 N 4 .…”

Insights into efficient transition metal-nitrogen/carbon oxygen reduction electrocatalysts

“…For example, Stariha et al [128] used fumed silica as a template to support the pyrolysis of ferric nitrate and mebendazole precursors followed by leaching in HF to wipe off the templates, obtaining high-concentration FeN x sites and highly porous structure. Zhu et al [129] also developed a mesoporous carbon with N,P co-coordinated manganese atom (MnNPC-1000) catalyst (Fig. 9), using silica colloid (SiO 2 ) as a template which was removed by following alkaline and acidic leaching.…”

“…Illustrations of the synthesis of MnNPC-1000 catalyst. Reproduced from Ref [129]. with permission from Wiley-VCH.…”

Oxygen Reduction Reactions on Single‐ or Few‐Atom Discrete Active Sites for Heterogeneous Catalysis

“…Another study involving Mn as single‐atom catalyst was published by Lu's group in 2019 . In this occasion, Mn–N x P y moieties were embedded on a mesoporous carbon composite after polymerization of o ‐phenylenediamine followed by calcination.…”