Ultrasmall Mo₂C Embedded in N‐Doped Holey Carbon for High‐Efficiency Electrochemical Oxygen Reduction Reaction

Abstract

The Oxygen reduction reaction (ORR) plays an important role in fuel cells, but the synthesis of efficient and low-cost catalysts remains challenging. We report the synthesis of ultra-small Mo 2 C nanoparticles with an average size of 1.5 nm embedded in a N-doped holey carbon (NHC) matrix by employing selfassembled macrocycle cucurbit[6]uril (CB[6]) and melamine as carbon precursors. The interaction between Mo precursors and CB[6] effectively prevented the aggregation of Mo 2 C NPs during the pyrolysis procedure. Besides, the holey structural carbon has a larger electrocatalytic activity area and improves mass transfer efficiency and charge transfer rate. The NHC features abundant defective sites and thus effective anchoring and electronic regulation for Mo 2 C nanoparticles. The electrochemical oxygen reduction activity of Mo 2 C/NHC is comparable to that of noble metal Pt/C benchmark catalyst with an initial potential, half-wave potential and limiting current density of 0.95 V, 0.84 V and 5.0 mA cm À 2 , respectively. Mo 2 C/NHC shows a good long-term durability during 25 h chronoamperometry.

In situ self-assembly of molybdenum carbide and iron carbide heterostructures on N-doped carbon for an efficient oxygen reduction reaction

“…18 Positioned as an early transition metal carbide, Mo 2 C presents itself as a formidable contender of platinum, the current gold standard for catalysts in the hydrogen evolution reaction (HER) and the ORR within fuel cells. 19,20 Mo 2 C-based catalyst composites are seen to enhance the ORR, encompassing B and N co-doped Mo 2 C. 21 Defect-enriched heterointerfaces in the form of N-MoO 2 -Mo 2 C supported Pd nanocomposites, 22 Mo 2 C embedded within N-doped holey carbon, 23 hierarchically mesoporous Mo 2 C/C structures 24 as well as Mo 2 C nanoparticles anchored on N-doped carbon nanotubes 25 cover a number of configurations. These studies illustrate a concerted effort to use the unique properties of Mo 2 C and its composites to optimize the ORR performance.…”