Engineering the Morphology and Microenvironment of a Graphene‐Supported Co‐N‐C Single‐Atom Electrocatalyst for Enhanced Hydrogen Evolution

Abstract

Graphene‐supported single‐atom catalysts (SACs) are promising alternatives to precious metals for catalyzing the technologically important hydrogen evolution reaction (HER), but their performances are limited by the low intrinsic activity and insufficient mass transport. Herein, a highly HER‐active graphene‐supported Co‐N‐C SAC is reported with unique design features in the morphology of the substrate and the microenvironment of the single metal sites: i) the crumpled and scrolled morphology of the graphene substrate circumvents the issues encountered by stacked nanoplatelets, resulting in improved exposure of the electrode/electrolyte interfaces (≈10 times enhancement); ii) the in‐plane holes in graphene preferentially orientate the Co atoms at the edge sites with low‐coordinated Co‐N3 configuration that exhibits enhanced intrinsic activity (≈2.6 times enhancement compared to the conventional Co‐N4 moiety), as evidenced by detailed experiments and density functional theory calculations. As a result, this catalyst exhibits significantly improved HER activity with an overpotential (η) of merely 82 mV at 10 mA cm−2, a small Tafel slope of 59.0 mV dec−1 and a turnover frequency of 0.81 s−1 at η = 100 mV, ranking it among the best Co‐N‐C SACs.

Activating bimetallic ZIF-derived polymers using facile steam-etching for the ORR

“…One explanation for the morphology changes may involve functional group decomposition upon volatilization of precursor 2 ; the resulting gas formed a transient high pressure between the lamella, which led to curly shapes of the micro/nanotubes. 25 This synthetic process was similar to flowers in nature which go through three stages: germination, flowering, and petal shedding. The morphology of α-Fe 2 O 3 /Fe@NPC was further examined via transmission electron microscopy (TEM) and high-resolution TEM (HR-TEM) (Fig.…”

Theoretical and experimental progress of metal electrocatalysts for the nitrogen reduction reaction

“…47 For the Co–N–C SAC, Huang et al replaced the perfect graphene substrate with crumpled and scrolled graphene, leading to the formation of Co–N 3 configuration, which enhanced the intrinsic activity compared to conventional Co–N 4 . 48 SACs have proved promising for catalysing the NRR due to the unique electronic structure, which can activate the inert N 2 favourably.…”

MOF-Derived Highly Active Co-N-C Hybrid Arrays for Efficient Hydrogen Evolution Reaction

“…The distribution of the active species on the substrate, such as graphene, [7] has been con rmed to be an important way to overcome the agglomeration effect, because the substrate guarantees the stronger anchoring of the active sites. Besides, the support also introduces more uent mass transfer and faster electron conduction.…”