Abstract
Chiral optical materials based on circularly polarized luminescence (CPL) have emerged rapidly due to their feasible applications in diverse fields of research. However, limited to the small ...luminescence dissymmetry factor (
g
lum
), real application examples have rarely been reported. Here, we present a complex system, which show intense circularly polarized ultraviolet luminescence (CPUVL) with large
g
lum
value, enabling a chiral UV light triggered enantioselective polymerization. By integrating sensitized triplet-triplet annihilation upconversion and CPL, both visible-to-UV upconversion emission and upconverted circularly polarized ultraviolet luminescence (UC-CPUVL) were obtained in the systems, built of chiral annihilator
R
(
S
)-4,12-biphenyl2,2paracyclophane (
R
-/
S
-TP), and a thermally activated delayed fluorescence (TADF) sensitizer. After dispersing this upconversion system into room-temperature nematic liquid crystal, induced chiral nematic liquid crystal could significantly amplify the
g
lum
value (0.19) of UC-CPUVL. Further, the UC-CPUVL emission has been used to trigger the enantioselective photopolymerization of diacetylene. This work paves the way for the further development of functional application of CPL active materials.
AgBr nanoparticles supported on graphitic‐C3N4‐decorated nitrogen‐doped graphene intercorrelated ternary superhybrid composites (ACNNG‐x) acting as a novel visible‐light driven photocatalyst are ...reported. Because of the fast interfacial charge separation and photoelectrochemical performance, the representative of ACNNG‐50 superhybrid structure achieves high efficiency and stable photocatalytic capability for organic contaminant degradation and CO2 reduction.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
It is commonly accepted that it is almost not possible to realize the large-scale practical application of fuel cells if the expensive noble metal-based electrocatalysts for oxygen reduction ...reactions (ORR) cannot be replaced by other low-cost, efficient, and stable ones. Herein, our studies demonstrate that iron phthalocyanine (FePc) supported on chemically reduced graphene through π–π interaction can act as a noble metal-free electrocatalyst with a comparable activity, long-term operation stability, and better tolerance to methanol crossover and CO poisoning compared with commercial Pt/C for ORR in alkaline media. The improved electrochemical activity and stability of FePc by graphene is mainly attributed to the inherent properties of graphene and the π-stacking interaction between FePc and planar aromatic structure of graphene. The as-prepared graphene–iron phthalocyanine (g-FePc) composite exhibits an efficient 4-electron pathway and can be used as a promising Pt-free ORR electrocatalyst.
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IJS, KILJ, NUK, PNG, UL, UM
We first reported that polyvinylpyrrolidone-protected graphene was dispersed well in water and had good electrochemical reduction toward O2 and H2O2. With glucose oxidase (GOD) as an enzyme model, we ...constructed a novel polyvinylpyrrolidone-protected graphene/polyethylenimine-functionalized ionic liquid/GOD electrochemical biosensor, which achieved the direct electron transfer of GOD, maintained its bioactivity and showed potential application for the fabrication of novel glucose biosensors with linear glucose response up to 14 mM.
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IJS, KILJ, NUK, PNG, UL, UM
A new type of eco-friendly molecularly imprinted polymer (MIP) was synthesized through an efficient one-pot room-temperature sol–gel polymerization and applied as a molecular recognition element to ...construct dopamine (DA) fluorescence (FL) optosensor. Highly luminescent carbon dots (CDs) were firstly synthesized via a one-step reaction in organosilane, and their surface were anchored with MIP matrix (CDs@MIP). The resulting composite of a synergetic combination of CDs with MIP showed high photostability and template selectivity. Moreover, the composite allowed a highly sensitive determination of DA via FL intensity decreasing when removal of the original templates. The new MIP-based DA sensing protocol was applied to detect DA concentration in aqueous solution, the relative FL intensity of CDs@MIP decreased linearly with the increasing DA in the concentration range of 25–500nM with a detection limit (3σ) of 1.7nM. Furthermore, the proposed method was successfully intended for the determination of trace DA in human urine samples without the interference of other molecules and ions.
► An eco-friendly CDs@MIP composite was synthesized. ► The synthesis process was a one-pot room-temperature sol–gel polymerization. ► CDs@MIP was the molecular recognition element of fluorescence optosensor. ► The optosensor exhibited high sensitive and selective towards dopamine.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
A novel glucose biosensor based on immobilization of glucose oxidase in thin films of chitosan containing nanocomposites of graphene and gold nanoparticles (AuNPs) at a gold electrode was developed. ...The resulting graphene/AuNPs/chitosan composites film exhibited good electrocatalytical activity toward H
2O
2 and O
2. The wide linear response to H
2O
2 ranging from 0.2 to 4.2
mM (
R
=
0.998) at −0.2
V, high sensitivity of 99.5
μA
mM
−1
cm
−2 and good reproducibility were obtained. The good electrocatalytical activity might be attributed to the synergistic effect of graphene and AuNPs. With glucose oxidase (GOD) as a model, the graphene/AuNPs/GOD/chitosan composite-modified electrode was constructed through a simple casting method. The resulting biosensor exhibited good amperometric response to glucose with linear range from 2 to 10
mM (
R
=
0.999) at −0.2
V and from 2 to 14
mM (
R
=
0.999) at 0.5
V, good reproducibility and detection limit of 180
μM. Glucose concentration in human blood was studied preliminarily. From 2.5 to 7.5
mM, the cathodic peak currents of the biosensor decrease linearly with increasing the glucose concentrations. The graphene/AuNPs/GOD/chitosan composites film shows prominent electrochemical response to glucose, which makes a promising application for electrochemical detection of glucose.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Propyl gallate (PG) as one of the important synthetic antioxidants is widely used in the prevention of oxidative deterioration of oils during processing and storage. Determination of PG has received ...extensive concern because of its possible toxic effects on human health. Herein, we report a photoelectrochemical (PEC) sensor based on ZnO nanorods and MoS2 flakes with a vertically constructed p–n heterojunction. In this system, the n-type ZnO and p-type MoS2 heterostructures exhibited much better optoelectronic behaviors than their individual materials. Under an open circuit potential (zero potential) and visible light excitation (470 nm), the PEC sensor exhibited extraordinary response for PG determination, as well as excellent anti-inference properties and good reproducibility. The PEC sensor showed a wide linear range from 1.25 × 10–7 to 1.47 × 10–3 mol L–1 with a detection limit as low as 1.2 × 10–8 mol L–1. MoS2/ZnO heterostructure with proper band level between MoS2 and ZnO could make the photogenerated electrons and holes separated more easily, which eventually results in great improvement of sensitivity. On the other hand, formation of a five membered chelating ring structure of Zn(II) with adjacent oxygen atoms of PG played significant roles for selective detection of PG. Moreover, the PEC sensor was successfully used for PG analysis in different samples of edible oils. It demonstrated the ability and reliability of the MoS2/ZnO-based PEC sensor for PG detection in real samples, which is beneficial for food quality monitoring and reducing the risk of overuse of PG in foods.
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IJS, KILJ, NUK, PNG, UL, UM
Graphene sheets functionalized covalently with biocompatible poly-l-lysine (PLL) were first synthesized in an alkaline solution. PLL-functionalized graphene is water-soluble and biocompatible, which ...makes it a novel material promising for biological applications. Graphene sheets played an important role as connectors to assemble these active amino groups of poly-l-lysine, which provided a very biocompatible environment for further functionalization, such as attaching bioactive molecules. As an example, an amplified biosensor toward H2O2 based on linking peroxidase onto PLL-functionalized graphene was investigated.
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IJS, KILJ, NUK, PNG, UL, UM
Peatlands store nearly 30% of global soil carbon, and they are widely distributed in mid- to high latitude regions that are sensitive to climate change and recently subject to more frequent fires. ...Fire not only causes direct effects on the growth of plant communities but also results in significant effects on organic matter (OM) sources and the stability of peatland carbon reservoirs; however, these long-term impacts are poorly understood, especially for permafrost peatlands. Based on a 210Pb age-depth model, we reconstructed historical variations in OM sources using the chemical properties of peatland sedimentary records at a site in the northern Great Khingan Mountains of China. Compared with the historical fire intensity and fuel sources reconstructed by the FTIR spectrum of pyrogenic carbon (PyC), the effects of fire on OM sources were analyzed for the last 150 years. Our results show that historically >70% of OM in the studied peatlands was sourced from shrubs, especially before 1980. Due to high-intensity fires which more easily burn herb plant litter, the major OM sources in burnt sites were shrubs, and herb plant litters were the major PyC sources. With fire management policies implemented at the end of the 1970s, fire frequency and intensity decreased markedly leading to a gradual decrease in the proportion of shrub OM from 75% to 50% from 1980 to 2000. Although fire intensity has increased since 2000, fire management interventions quickly extinguish most fires and decrease the effects of fires on herb plant litters. Both climate warming and high-intensity fire promote more herbs growing in burned peatlands, and the residual herb/moss plant litters became the major OM sources after 2000.
•Impact of fire on long-term peatland organic matter (OM) sources was evaluated.•High intensity fires led the major sources of residual OM in peatlands being shrubs.•Herb plant litters more easily consumed and converted to pyrogenic carbon.•Fire management policies decrease the shrub OM proportion from 75% to 50% after 1980.•Climate warming and fire control led the herb/moss being the major OM sources.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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