Semiconductors are usually employed to construct photocatalysts for hydrogen production, but bare semiconductors often suffer from a high recombination rate of charge carriers, resulting in low ...activity for proton reduction. Herein, CdS quantum dots (QDs) were anchored onto a tremella-like N-doped carbon (NC) support with trace ruthenium dispersed, to store and consume photo-excited electrons. The Ru/NC cocatalyst significantly enhances the interfacial transfer of electrons and facilitates proton reduction, leading to a decrease in the photoinduced charge recombination. The optimal Ru/NC/CdS-5 catalyst has a low Ru loading of 0.59 wt%, and it exhibits the highest photocatalytic activity with an H
2
evolution rate of up to 73.6 mmol g
−1
h
−1
, which is 21 times higher than that of bare CdS QDs (3.38 mmol g
−1
h
−1
). The apparent quantum yield (AQY) of Ru/NC/CdS-5 under the same experimental conditions was found to be 3.6% under irradiation at 420 nm. The catalytic recycling test of Ru/NC/CdS-5 demonstrates its excellent stability. This work provides insight into the enhancement of the activity of semiconductors by dispersing a trace noble metal in a porous carbon support as a cocatalyst for proton reduction.
The employment of Ru/NC effectively retards the recombination of charge carriers by the storage and consumption of photo-excited electrons, achieving a significantly improved activity for H
2
evolution, which is 21 times higher than that of bare CdS QDs.
A reversing differential pulse voltammetry (RDPV) with a pre-accumulation step has been developed for simultaneous determination of quercetin and rutin in a mixture. A multi-wall carbon-nanotube ...paste electrode (CNTPE) was used for this purpose. Quercetin presented two oxidation steps at
E
m of 0.155 and
E
pa of 0.360
V versus SCE, and rutin presented only one oxidation step at
E
m of 0.316
V at the CNTPE. Strong adsorption and favorable assembly process of these species were observed on the electrode surface, based on which these species could be significantly pre-accumulated at the electrode for determination, resulting in considerably increased signals with well separated voltammetric peaks, allowing simultaneous detection. RDPV technique was used to select the first anodic peak of quercetin and the re-reduction peak of rutin for the determination, avoiding the peak overlap interferences. The electrochemical system was optimized for the selection of a suitable buffer system and pre-accumulation parameters such as adsorption potential and time duration. Finally, the multi-wall CNT paste electrode, as an electrochemical sensor, gave detecting sensitivities as high as 4.90
μA/(μM quercetin) in the linear range of 0.05–5
μM (in the presence of 10
μM rutin) and 2.43
μA/(μM rutin) in the linear range of 0.1–10
μM (in the presence of 10
μM quercetin). The applicability of the method to real sample analysis was also evaluated.
Maternal stress has been associated with poor birth outcomes, including preterm birth, infant mortality, and low birth weight. Bone development disorders in the embryo as a result of maternal stress ...are believed to be mediated through oxidative stress damage. Various species of free radicals, such as alkoxyl radicals, can be formed through endogenous redox response or exogenous stimuli in the womb and transmitted to embryos. Yet, whether these free radicals lead to abnormal fetal bone development is unclear. Here, we demonstrate prenatal bone growth retardation and ferroptosis-related signals of chondrocytes were induced by classic alkoxyl radical generators. We also show that alkoxyl radicals lead to significant accumulation of oxidized phospholipids in chondrocytes, through the iron-mediated Fenton reaction in embryos. We further demonstrate a role for the lipid peroxidation end product, 4-HNE, which forms adducts with the pivotal chondrogenesis transcription factor SOX9, leading to its degradation, therefore dampening chondrogenesis. Our data define a critical role for phospholipid peroxidation in alkoxyl radicals-evoked abnormal chondrogenesis, and pinpoint it being a precise target for treating oxidative stress-related bone development disorders.
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•Alkoxyl radicals retard embryonic skeleton development.•Alkoxyl radicals-induced accumulation of oxidized phospholipids dampen chondrogenesis.•Alkoxyl radicals trigger phospholipid peroxidation via iron-mediated Fenton reaction.•Lipid peroxidation end product, 4-HNE, forms adducts with SOX9 to promote its ubiquitin-dependant degradation.
This work presents a voltammetric method for measuring the electrocatalytic activity of gradient materials as a function of position across the material surface. The Ni−Cu−Fe gradient alloys are ...deposited on nickel substrates by bipolar electrochemistry and tested as an electrocatalyst for oxygen evolution reaction (OER). We attempt “area‐step” cyclic voltammetry to continuously measure the local electrocatalytic activity of the gradient alloys, by serially increasing the contact area between the electrolyte and the gradient surface. The local surface roughness can also be characterized using the same procedure. The parallel experiments consistently point to the same position where presents the highest intrinsic OER activity. Both the Fe content in the alloys and the surface roughness play important roles in the OER.
Area‐step cyclic voltammetry: A Ni−Cu−Fe gradient alloy is deposited on a nickel substrate by bipolar electrochemistry. Both the surface roughness (rn) and the electrocatalytic activity for oxygen evolution reaction (OER) vary as a function of position along the gradient direction. The area‐step cyclic voltammetry method is developed for measuring the local rn and OER activity, by serially increasing the contact area between the electrolyte and the gradient surface.
We reported on the soliton booting dynamics of an ultrafast fiber laser operating in an anomalous dispersion regime. Based on the advanced experimental methodologies of spatio-temporal reconstruction ...and dispersive Fourier transform (DFT), the soliton booting dynamics are analyzed in the time and spectral domains. The spectral interference pattern with strong intensity oscillation behavior was observed near the mode-locking transition. It was found that the spectral pattern distributions are induced by the transient structured soliton formation during the pulse shaping from the noise background. The experimental results were further verified by the theoretical simulations. The obtained results would provide a general guideline for understanding the soliton booting dynamics in the ultrafast fiber lasers, and will prove to be fruitful to the various communities interested in solitons and fiber lasers.
Taking advantage of technology of spatio-temporal reconstruction and dispersive Fourier transform (DFT), we experimentally observed the buildup dynamics of dissipative soliton in an ultrafast fiber ...laser in the net-normal dispersion regime. The soliton buildup dynamics were analyzed in both the spectral and temporal domains. We firstly revealed that the appearing of the spectral sharp peaks with oscillation structures during the mode-locking transition is caused by the formation of structural dissipative soliton. The experimental results were explained by the numerical simulations. These findings would give some new insights into the dissipative soliton buildup dynamics in ultrafast fiber lasers.
Retaining soluble polysulfides in the sulfur cathodes and allowing for deep redox are essential to develop high-performance lithium–sulfur batteries. The versatile textures and physicochemical ...characteristics of abundant biomass offer a great opportunity to prepare biochar materials that can enhance the performance of Li–S batteries in sustainable mode. Here, we exploit micro-/mesoporous coconut shell carbon (CSC) with high specific surface areas as a sulfur host for Li–S batteries. The sulfur-infiltrated CSC materials show superior discharge–charge capacity, cycling stability, and high rate capability. High discharge capacities of 1599 and 1500 mA h g–1 were achieved at current rates of 0.5 and 2.0 C, respectively. A high reversible capacity of 517 mA h g–1 was retained at 2.0 C even after 400 cycles. The results demonstrate a high retention and a deep lithiation of the CSC-confined sulfur. The success of this strategy provides insights into seeking high-performance biochar materials for Li–S batteries from abundant bioresources.
The adsorption and oxidation behavior of rutin was studied by in-situ UV spectroelectrochemistry in a long optical-path thin-layer electrochemical cell with a graphite-wax electrode. The dynamic UV ...spectra of rutin under potentiostatic oxidation were recorded, which indicated the formation of
o-quinonic structure. During the repetitive cyclic potential scans, cyclic voltabsorptomogram was recorded at the three characteristic wavelengths 346, 254 and 296 nm, respectively. The profiles obtained showed two types of concentration fluctuation of species in solution, resulting from adsorption/desorption and redox reaction, respectively. Using derivative cyclic voltabsorptometry the contribution of the species in solution to the total current was estimated, and then the current of every step involved in the proposed redox mechanism was obtained for the first time. The result shows that rutin underwent a nearly reversible redox reaction in which the total current is mostly due to the contribution of adsorbed species. The present work developed cyclic voltabsorptometry into a useful tool for investigating redox process involving coupled adsorption/desorption steps.
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•A novel bipolar electrochemical flow microreactor.•A combination of bipolar electrochemistry and flow electrolysis techniques.•A separate electrodeposition of mixed metal ions on a ...single bipolar electrode.•A potential application in efficient recovery of valuable metals.
A combination of bipolar electrochemistry and flow electrolysis is used to develop a bipolar electrochemical flow microreactor to separately deposit mixed metal ions onto different positions of a single bipolar electrode. The potential gradient along the electrode surface was studied as a function of driving voltage, background solution concentration, solution thickness and connecting hose length. FESEM-EDX analyses indicated that both a gold-copper alloy (ca. 80 atom% Au) and bulk copper were recovered from a solution containing 0.125 mM AuCl4− and 20 mM Cu2+. This work provides a new bipolar flow microreactor for possible application in the efficient recovery of valuable metals from electronic industrial wastes.
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