An off-beam (OB) detection approach is suggested and experimentally investigated and optimized for quartz-enhanced photoacoustic spectroscopy (QEPAS). This OB-QEPAS configuration, very simple in assembly, not only allows for use of larger excitation optical beams and facilitating optical alignment but also provides higher enhancement of photoacoustic signals than previously published results based on the common on-beam QEPAS under the same experimental conditions. A normalized noise equivalent absorption coefficient (1sigma) of 5.9 x 10(-9) cm(-1)W/Hz(1/2) was obtained for water vapor detection at normal atmospheric pressure.
Building heterostructures containing dissimilar coupling components with different bandgaps can promote interfacial reaction kinetics and accelerate charge carrier transport for Li–S batteries.
The conjugated polyaniline and water co-intercalating-vanadium oxide rose-like architectures with larger interlayer spacing and improved electronic conductivity display unprecedented electrochemical properties for low cost zinc battery application.
Metal
sulfides have attracted tremendous research interest for
developing high-performance electrodes for potassium-ion batteries
(PIBs) for their high theoretical capacities. Nevertheless, the practical
application of metal sulfides in PIBs is still unaddressed due to
their intrinsic shortcomings of low conductivity and severe volume
changes during the potassiation/depotassiation process. Herein, robust
Fe7S8/C hybrid nanocages reinforced by defect-rich
MoS2 nanosheets (Fe7S8/C@d-MoS2) were designed, which possess abundant multichannel and active
sites for potassium-ion transportation and storage. Kinetic analysis
and theoretical calculation verify that the introduction of defect-rich
MoS2 nanosheets dramatically promotes the potassium-ion
diffusion coefficient. The ex-situ measurements revealed
the potassium-ion storage mechanism in the Fe7S8/C@d-MoS2 composite. Benefitting from the tailored structural
design, the Fe7S8/C@d-MoS2 hybrid
nanocages show high reversible capacity, exceptional rate property,
and superior cyclability.
Rechargeable magnesium batteries are particularly advantageous for renewable energy storage systems. However, the inhomogeneous Mg electrodeposits greatly shorten their cycle life under practical conditions. Herein, the epitaxial electrocrystallization of Mg on a three-dimensional magnesiophilic host is implemented via the synergy of a magnesiophilic interface, lattice matching, and electrostatic confinement effects. The vertically aligned nickel hydroxide nanosheet arrays grown on carbon cloth (abbreviated as "Ni(OH) 2 @CC") have been delicately designed, which satisfy the essential prerequisite of a low lattice geometrical misfit with Mg (about 2.8%) to realize epitaxial electrocrystallization. Simultaneously, the ionic crystal nature of Ni(OH) 2 displays a periodic and hillock-like electrostatic potential field over its exposed facets, which can precisely capture and confine the reduced Mg 0 species onto the local electron-enriched sites at the atomic level. The Ni(OH) 2 @CC substrate undergoes sequential Mg-ion intercalation, underpotential deposition, and electrocrystallization processes, during which the uniform, lamellar Mg electrodeposits with a locked crystallographic orientation are formed. Under practical conditions (10 mA cm −2 and 10 mAh cm −2 ), the Ni(OH) 2 @ CC substrate exhibits stable Mg stripping/plating cycle performances over 600 h, 2 orders of magnitude longer than those of the pristine copper foil and carbon cloth substrates.
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