A Mo2C based electrocatalyst (Mo2C@SNC) was
successfully synthesized with sulfur and nitrogen codoped carbon (SNC)
as the matrix, which was derived from the shells of sunflower seeds.
In the Mo2C/SNC, Mo2C particles that range in
size from approximately 5 to 8 nm are evenly distributed in the sulfur
and nitrogen codoped carbon matrix. Moreover, Mo2C/SNC
has a large specific surface area with a mesoporous character. These
particular structural features result in Mo2C@SNC having
good electrocatalytic activity for hydrogen evolution reaction (HERs).
To obtain 10 mA·cm–2 current in 1 M KOH, Mo2C@SNC only needs an overpotential as low as 60 mV. Mo2C@SNC also has outstanding durability and remains stable for
over 2000 cycles. During a HER process, its hydrogen evolution rate
reaches 90.2 μmol·h–1, with faradaic
efficiency reaching almost 100%. Under acidic conditions, the advantages
of Mo2C@SNC are obvious. In addition to electrocatalytic
hydrogen evolution, Mo2C@SNC exhibits striking catalytic
activity for the reduction of 4-nitrophenol to 4-aminophenol. The
conversion efficiency reaches almost 100% in 6 min with only a small
amount of Mo2C@SNC used for the catalyst. In addition to
4-nitrophenol, Mo2C@SNC also affects methylene blue (MB),
a common organic dye. We expect that Mo2C@SNC will become
a new resource for H2 energy and will be a prospective
material for water purification.
To
obtain the photocatalyst composed by sulfur vacancies rich NiS
and graphitic carbon nitride (g-C3N4), a simple
method has been found for using coordination polymer as precursor.
Based on this strategy, an effective composite photocatalyst, NiS@g-C3N4, is synthesized successfully through the calcination
of a Ni2+ based coordination polymer with 2-mercapto-5-propylpyrimidine
as ligand. In this photocatalyst, the NiS nanoparticles with small
size disperse evenly in 2-mercapto-5-propylpyrimidine derived g-C3N4. Electron paramagnetic resonance (EPR) suggests
there are a lot of sulfur vacancies in NiS@g-C3N4. NiS@g-C3N4 exhibits intensive adsorption
in the near-infrared region, which endows NiS@g-C3N4 with promising photothermal effect. With a 980 nm laser as
light source (0.44 W·cm–2), the aqueous dispersion
of NiS@g-C3N4 exhibits a temperature elevation
of 56.7 °C with photothermal conversion efficiency of 58.2%.
Under irradiation of simulated solar light, without Pt co-catalyst,
NiS@g-C3N4 possesses a promising photocatalytic
H2 production rate, with the value 31.3 mmol·g–1·h–1. In five cycles of reactions
for 30 h, the H2 production rate remains constant. The
synergy between sulfur vacancy and photothermal effect of NiS play
significant roles in the enhancement of H2 production property.
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