Reaction Packaging CoSe₂ Nanoparticles in N-Doped Carbon Polyhedra with Bifunctionality for Overall Water Splitting

Abstract

Water electrolysis is a promising approach for green and large-scale hydrogen production; however, there are still challenges for developing efficient and stable bifunctional electrocatalysts toward the hydrogen and oxygen evolution reactions. Herein, zeolitic imidazolate framework-67 was used as the precursor for the construction of CoSe2 nanoparticles trapped in N-doped carbon (NC) polyhedra. Among as-obtained CoSe2-NC hybrid, highly active CoSe2 nanoparticles in sizes of 10–20 nm are encapsulated in N-doped few-layer carbon shell, avoiding their easy aggregations of CoSe2 nanoparticles as well as enhancing the long-term stability. The unique nanostructured CoSe2-NC hybrid with a hierarchical porosity and 3D conductive framework thus fully exerts outstanding bifunctional catalytic activity of CoSe2 centers. As a result, the CoSe2-NC hybrid as bifunctional catalysts for overall water splitting delivers a high current density of 50 mA cm–2 with an applied voltage of ∼1.73 V in an alkaline electrolyte, with a promising stability over 50 000 s.

Solvent‐Exchange Strategy toward Aqueous Dispersible MoS2 Nanosheets and Their Nitrogen‐Rich Carbon Sphere Nanocomposites for Efficient Lithium/Sodium Ion Storage

“…In general, Nyquist plots consist of a semicircle in the high‐frequency region and a straight line with a constant inclining angle in the low‐frequency region, which are associated with the charge‐transfer resistance and the solid‐state diffusion resistance of Li ions in the electrode, respectively 5a. In comparison with neat f‐MoS 2 , the diameter of semicircles at the high frequency are greatly lessened for the MoS 2 ‐NCS nanocomposites, indicating the remarkably reduced resistances for charge transfer and ion diffusion during the lithiation/delithiation process for the MoS 2 ‐NCS nanocomposite electrodes …”

“…[5a] In comparison with neat f-MoS 2 , the diameter of semicircles at the high frequency are greatly lessened for the MoS 2 -NCS nanocomposites, indicating the remarkably reduced resistances for charge transfer and ion diffusion during the lithiation/delithiation process for the MoS 2 -NCS nanocomposite electrodes. [36] Small 2019, 15,1903816 As a result, the MoS 2 -NCS nanocomposites own several beneficial features as anode materials for high-performance LIBs: 1) The f-MoS 2 straightly coated with NCS renders MoS 2 -NCS nanocomposites boosting the charge transfer rates and electrical contacting areas, especially along x-axis. 2) The NCS coatings significantly promote the adsorption and intercalation of Li ions.…”

Three‐Dimensional Graphene‐Foam‐Supported Hierarchical Nickel Iron Phosphide Nanosheet Arrays as Efficient and Stable Bifunctional Electrocatalysts for Overall Water Splitting

“…This can also be mutually confirmed by the high OER and HER catalytic activities of NiFe‐P@3DGF. Such a high ECSA value for electrocatalysts is very impressive, much higher than those on the recently reported bifunctional catalysts including CoSe 2 ‐NC hybrid (12 mF cm −2 ), NiCoP NR@NS (13.5 mF cm −2 ) and P 8.6 ‐Co 3 O 4 /NF (60.54 mF cm −2 ) . In addition, the electrochemical impedance spectroscopy (EIS) is an effective approach to evaluate the charge transfer kinetics in the catalytic process.…”

Cobalt-Based Metal-Organic Frameworks and Their Derivatives for Hydrogen Evolution Reaction

“…Thus, using MOFs as precursors to introduce carbon nanomaterials has become a popular research subject. According to the morphological relationship between the carbon material and CoSe 2 , it can be divided into coating (Zhou W. et al, 2016 ; Meng et al, 2017 ; Lu et al, 2019 ; Ding et al, 2020 ) and loading (Park and Kang, 2018 ). By coating with carbon materials, the agglomeration and corrosion of CoSe 2 can be largely restricted (Zhang F. et al, 2019 ; Zhang L. et al, 2019 ; Ding et al, 2020 ).…”