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.
Summary
The morphology and structure of the electrocatalysts are important factors affecting their performance for electrochemical splitting water into hydrogen. Herein, the urchin‐like CoP nanomaterials with the large specific surface area (SSA) were fabricated through the solvothermal process and the solid‐gas reaction for hydrogen evolution reaction (HER). The resulting CoP nanomaterial with a diameter of approximately 4 μm was assembled by the nanowires with a length of about 10 nm. The excellent performance is accessible for HER with a small overpotential of 130 mV and a low Tafel slope of 52 mV/decade in a 0.5 M H2SO4 aqueous solution. Especially, the resulting urchin‐like CoP nanomaterials with a large SSA and electric double‐layer capacitance lower the electrochemical impedance and accelerate the electron transfer, endowing the excellent performance for HER process.
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