Hierarchical Nickel Clusters Encapsulated in Ultrathin N-doped Graphitic Nanocarbon Hybrids for Effective Hydrogen Evolution Reaction

Abstract

Three-dimensional (3D) nanospheres with a hollow interior derived from self-sacrificing templates have triggered great enthusiasm due to their structure-related performance for splitting water into hydrogen. Herein, a nickel-organic compound constituted of elemental nickel and glycine was first synthesized through a solvothermal process in an ethyl alcohol solution. Then, novel 3D hierarchical nanocatalysts consisting of ultrathin N-doped graphitic-nanocarbon-coated nickel clusters with a hollow interior structure were facilely fabricated via calcining the prepared nickel-organic compound. Outstanding electrocatalytic activity with a small overpotential of 70 mV and a low Tafel slope of 119 mV dec–1 for the hydrogen evolution reaction process can be readily achieved in a 1 M KOH aqueous solution through a controllable synthesis method. The investigation on electrocatalytic activity certifies that the thickness of the graphitic nanocarbon shells has a great influence on water splitting efficiency for hydrogen; the thinner the graphitic nanocarbon shells, the more excellent the electrocatalytic efficiency. Additionally, the detailed electrochemically active surface area suggests that the 3D hollow structured hybridized electrocatalysts with defect-rich ultrathin graphitic nanocarbon shells could limit the aggregation of nickel clusters, and small electrochemical impedance accelerates the penetration of electrons, inducing a high efficiency for electrochemical water splitting. Therefore, thoughtful design using the self-sacrificing template method provides a promising strategy for the fabrication of other hybridized composites with hierarchical architectures consisting of nanoclusters and nanocarbon for more efficient water splitting.

Urchin‐like CoP nanomaterial as an electrocatalyst for efficient hydrogen evolution reaction

“…The CHI 760E electrochemical workstation was performed to evaluate the electrochemical performances. More details resemble the method of our previous report 15 and are provided in the SI.…”

“…Recently, great progress have been made to exploit the alternative candidates constituted by the 3d transition metals, that is, the oxides/hydroxides, selenides, nitrides, borides, carbide, as well as sulfides and phosphates for water splitting. [13][14][15] Among the aforementioned electrocatalysts, transition metal phosphides (TMP) hold unique electronic structures and adsorption properties for intermediates, benefiting the HER process and thus becoming research hotspots. 16,17 Besides, properly constructing the nanostructure of the catalyst is an effective tactic to strengthen the electrocatalytic efficiency.…”

Carbon Nanotube‐Based Non‐Precious Metal Electrode Catalysts for Fuel Cells, Water Splitting and Zinc‐Air Batteries

“…Hence, the development of efficient catalysts for the HER is vital for the practical applicability of an alkaline environment compared to the acidic environment. Though the state‐of‐the‐art catalysts, such as Pt/C, Pt−Co/C, etc., are used in commercial markets, few of the non‐precious catalysts, such as carbon supported and without carbon supports, can potentially compete with the state‐of‐the‐art catalysts. The metal chalcogen is able to support fast electrode kinetics (Tafel‐Volmer pathway).…”

“…Ma et al . developed an ultrathin threonic acid intercalated MoS 2 nanomaterial by a homogeneous hydrothermal precipitation method in the presence of Na 2 MoO 4 ⋅ 2H 2 O, thiourea, and ascorbic acid . After the graphitization process, the obtained carbon supported MoS 2 hybrid provided a remarkably low overpotential of 195 mV and a Tafel slope of 53 mV/decade in a 0.5 M H 2 SO 4 aqueous solution.…”

Construction of hollow structure cobalt iron selenide polyhedrons for efficient hydrogen evolution reaction

“…In the process of hydrogen produced from electrolysis of water, it is often necessary to consume huge electric energy because of the high cathode overpotential. 8 The study of water electrolysis mainly focuses on reducing consumption. Catalysts can reduce the energy consumption of electrolysis.…”