Carbon materials are generally preferred as anodes in supercapacitors; however, their low capacitance limits the attained energy density of supercapacitor devices with aqueous electrolytes. Here, we report a low-crystalline iron oxide hydroxide nanoparticle anode with comprehensive electrochemical performance at a wide potential window. The iron oxide hydroxide nanoparticles present capacitances of 1,066 and 716 F g−1 at mass loadings of 1.6 and 9.1 mg cm−2, respectively, a rate capability with 74.6% of capacitance retention at 30 A g−1, and cycling stability retaining 91% of capacitance after 10,000 cycles. The performance is attributed to a dominant capacitive charge-storage mechanism. An aqueous hybrid supercapacitor based on the iron oxide hydroxide anode shows stability during float voltage test for 450 h and an energy density of 104 Wh kg−1 at a power density of 1.27 kW kg−1. A packaged device delivers gravimetric and volumetric energy densities of 33.14 Wh kg−1 and 17.24 Wh l−1, respectively.
Electrocatalytic water splitting is one of the sustainable and promising strategies to generate hydrogen fuel but still remains a great challenge because of the sluggish anodic oxygen evolution reaction (OER). A very effective approach to dramatically decrease the input cell voltage of water electrolysis is to replace the anodic OER with hydrazine oxidation reaction (HzOR) due to its lower thermodynamic oxidation potential. Therefore, developing the low-cost and efficient HzOR catalysts, coupled with the cathodic hydrogen evolution reaction (HER) is tremendously important for energysaving electrolytic hydrogen production. Herein, a new-type copper-nickel nitride (Cu 1 Ni 2 -N) with rich Cu 4 N/Ni 3 N interface is rationally constructed on the carbon fiber cloth. The three-dimensional electrode exhibits extraordinary HER performance with an overpotential of 71.4 mV at 10 mA cm -2 in 1.0 M KOH, simultaneously delivering an ultralow potential of 0.5 mV at 10 mA cm -2 for HzOR in 1.0 M KOH/0.5 M hydrazine electrolyte. Moreover, the electrolytic cell utilizing the synthesized Cu 1 Ni 2 -N electrode as both the cathode and anode displays a cell voltage of 0.24 V at 10 mA cm -2 with an excellent stability over 75 h. The present work develops the promising copper-nickel-based nitride as a bifunctional electrocatalyst through hydrazine-assistance for energy-saving electrolytic hydrogen production.
Silver cluster-assembled materials
(SCAMs), by virtue of their
tunable structure, accessible surface area and excellent stability,
hold great promise as highly efficient catalysts. Herein, we report
a new SCAM [Ag12(S
t
Bu)6(CF3COO)3(TPyP)]
n
(denoted as Ag12TPyP) composed of a Ag12 chalcogenolate cluster core stabilized by porphyrinic ligands. Ag12TPyP showed superior sulfur mustard simulant (2-chloroethyl
ethyl sulfide, CEES) degradation efficiency and achieved a half lifetime
(t
1/2) of 1.5 min with 100% selectivity.
The experimental results demonstrated that synergistic effects between
the silver cluster and photosensitizer ligand promote the efficiency
of the generation of singlet oxygen (1O2), which
accelerates the decontamination rate. Additionally, benefiting from
strong affinity between the silver cluster and CEES, Ag12TPyP exhibits a CEES uptake of 74.2 mg g–1. This
work demonstrates that SCAMs offer a new route to the rational design
of novel materials for the detoxification of mustard gas.
Unique
interfacial properties within heterostructures play vital
roles in enhancing hydrogen evolution reaction (HER) electrocatalysis.
On the basis of the MoO2-Ni heterostructure, we hereby
propose an upraised atomic orbital promoted catalytic mechanism for
accelerating the HER kinetics. A controllable gradient-pyrolysis approach
is adopted on molybdates to integrate Ni with MoO2, possessing
numerous phase-separation-induced intimate interfaces. In situ characterizations
demonstrate the formation process of MoO2-Ni interfaces
and excellent compositional stability under alkaline conditions. The
optimized MoO2-Ni catalyst delivers remarkable Pt-like
HER activity and good stability with 50 h operation in 1 M KOH. An
enhancement of 3 orders of magnitude on the exchange current density
is achieved for MoO2-Ni in comparison to the simplex MoO2. Further experimental and theoretical analyses verify the
existence of a concentrated surface charge at MoO2-Ni interfaces.
Meanwhile, with the incorporation of Ni into MoO2, the
most active sites dramatically change from Mo to O atoms at MoO2-Ni interfaces. The Ni contact upraises the O 2p orbital in
MoO2, thus strengthening the hydrogen adsorption for enhanced
HER kinetics.
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