Developing
effective and priceless electrocatalysts is an indispensable
requirement for advancing the efficiency of water splitting to get
clean and sustainable fuels. Herein, we reported a feasible strategy
for preparing a trimetallic (NiCoFe) superior electrocatalyst with
a novel open-cage/3D frame-like structure for an oxygen evolution
reaction (OER). It is prepared by consequent thermal treatments of
a CoFe Prussian blue analogue frame/cage-like structure under an argon
(CoFeA-TT) atmosphere and then electrochemical deposition of nickel-cobalt
sulfide nanosheets as a shell layer on it. The electrochemical measurements
demonstrated that the deposition of NiCo-S on CoFeA-TT (NiCo-S@CoFeA-TT)
has the best catalytic performance and can drive the benchmark current
density of 10 mA cm–2 at a low overpotential of
268 mV with a Tafel slope of 62 mV dec–1 and an
excellent long-term catalytic stability in an alkaline medium. Its
outstanding electrocatalytic performances are endowed from frame/cage-like
structures, highly exposed active sites, accelerated mass and electron
transport, and the synergistic effect of multiple hybrid components.
The NiCo-S@CoFeA-TT showed a better performance than most advanced
nonprecious catalysts and the noble commercial RuO2 catalyst.
This study exhibited an effective and efficient procedure to design
3D porous architecture catalysts for the energy-relevant electrocatalysis
reaction.
Engineering earth-rich, high-efficiency,
and nonprecious electrocatalysts
is an essential demand for water electrolysis to obtain clean and
sustainable fuels. In this research, novel hybrid electrocatalysts
based on coupling a hierarchical porous NiCo-mixed metal sulfide with
a nanosheet structure (denoted as NiCoS) and a novel three-dimensional
(3D) mesoporous open-cage/framelike structure of CoFeS are designed
for oxygen evolution reaction (OER). In this regard, the single-step
synthesis of a cobalt iron Prussian blue analog (CoFe PBA) frame/cagelike
structure was performed without any etching step. Following a comparative
study, CoFe PBA precursors were converted and doped with S, Se, and
P vapors (CoFeS, CoFeSe, and CoFeP) by annealing the precursors with
sulfur, selenium, and sodium hypophosphite powders, respectively.
The electrochemical measurements demonstrated that CoFe doped with
S and Se almost have similar performances for OER and are better than
the P-doped one. In the last step, NiCoS nanosheet arrays were electrodeposited
as a shell layer on CoFe (S, Se, and P) to examine their effect on
the catalytic activity toward OER, and CoFeS@NiCoS showed better catalytic
activity than CoFeSe@NiCoS and CoFeP@NiCoS. It can show the lowest
overpotential of 293 mV at a current density of 100 mA cm–2 with a Tafel slope of 40.6 mV dec–1 and has pre-eminent
long-range catalytic durability in 1.0 M KOH. This performance was
comparable to those of noble-metal-free and commercial RuO2 catalysts. Its excellent electrocatalytic activity benefits from
the frame/cagelike and nanosheet structures and good synergistic effects
between multiple hybrid components (Ni, Co, Fe, and S), which leads
to producing highly exposed active sites and accelerating mass and
electron transport. This study represents an efficient approach to
rationally design and synthesize three-dimensional porous architecture
catalysts based on transition metals as highly efficient nonprecious
electrocatalysts for the energy-pertinent reaction.
Fabrication of reasonable nanoarchitectures for electroactive
materials
is regarded as one the important strategies for the enhancement of
their electrocatalytic activity. Herein, CuCo2O4 nanorods and nanospheres were synthesized using a solvo-/hydrothermal
method followed by annealing treatment. Then, Co3S4 nanosheets were grown on CuCo2O4 nanostructures
by the electrochemical deposition method to form Co3S4/CuCo2O4 hybrid nanoarchitectures as
active sensing materials for the determination of glucose and hydrogen
peroxide. In comparison to the sphere-shaped Co3S4/CuCo2O4 nanocomposite, the CuCo2O4 nanorods anchored to Co3S4 nanosheets
displayed superior electrocatalytic properties toward glucose oxidation
and H2O2 reduction due to their high electrical
conductivity and large surface area. The rod-like nanocomposite exhibited
wide linear ranges (0.001–0.405 and 0.405–5.03 mM),
high sensitivities (1062.50 and 512.50 μA mM–1 cm–2), low detection limit (2.1 μM), excellent
selectivity, and long-term stability for glucose sensing. In addition,
this sensor provided satisfactory results for determination of glucose
in real biological samples. The as-proposed nanorod sensor also provided
a high sensitivity (275 μA mM–1 cm–2) toward hydrogen peroxide reduction with a wide linear range of
0.001–4.03 mM and negligible interfering effects. These results
suggest that the as-prepared electrocatalyst provides a promising
sensing platform for the analysis of biological samples.
Nonprecious and effective electrocatalyst
development is an essential
requirement for boosting water-splitting efficiency to obtain clean
and sustainable fuels for future renewable energy demands. Herein,
we reported an ultrafast and feasible strategy for constructing an
S-doped bimetallic iron/nickel oxy(hydroxide) (S-(Fe/Ni)OOH) as a
superior electrocatalyst for oxygen evolution reaction (OER). It is
prepared by consequent electroplating of nickel nanocone arrays (NiNCAs)
on carbon cloth (CC) and stainless-steel mesh (SSM) and then formation
of S-(Fe/Ni)OOH layers on them by ultrafast one-step oxidation solution-phase
method in the solution of Fe3+ and sodium thiosulfate at
room temperature. The derived composite material [S-(Fe/Ni)OOH@NiNCAs
on SSM and CC] exhibited high electrocatalytic activity toward OER
as well as good durability. The electrochemical measurements demonstrate
that S-(Fe/Ni)OOH@NiNCAs-CC and S-(Fe/Ni)OOH@NiNCAs-SSM can drive
the benchmark current density of 10 mA cm–2 at low
overpotentials of 248 and 245 mV and current density of 100 mA cm–2 at overpotentials of 327 and 312 mV with a Tafel
slope of 77 and 65 mV dec–1, respectively. Their
outstanding electrocatalytic performances are benefited from porous,
highly exposed active sites, accelerated mass and electron transport,
and synergistic effects. The prepared composite electrodes act better
than most advanced priceless catalysts and noble commercial RuO2 catalysts. This work provides an effective and efficient
approach to design porous architecture catalysts on a three-dimensional
substrate (SSM and CC) with high performance for energy-relevant and
electrocatalysis reactions.
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