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Developing efficient metal-free catalyst for the glycolysis of waste poly(ethylene terephthalate) (PET) with ethylene glycol (EG) has attracted increasing attention due to the demanding requirement for high-quality monomer used in regeneration. Herein, a new kind of efficient metal-free catalyst phosphazene base (t-BuP2) was developed through the combination of theoretical prediction and experimental verification approaches, which could achieve 100% conversion of PET and obtain BHET yield (92.7%) comparable to metal-based catalysts. The high efficiency of t-BuP2 comes from the facile generation of EG−, which has a strong ability to break the PET chain through a nucleophilic attack on the carbonyl group. t-BuP2 was selected as the catalyst based on the theoretical evaluation of the proton abstract ability of various bases through natural bond orbital analysis and reaction energy calculations, which could deprotonate EG barrierlessly to produce EG−. Next, the nucleophilic attack of EG− on the carbon atom of the carbonyl group in PET occurs, which greatly weakens the strong C–O bond on the PET chain. Then, the C–O bond was cleaved (rate-determining step) with the Gibbs activation energy and Gibbs reaction energy of 20.2 and −3.8 kcal mol−1, respectively, which was followed by the glycolysis step to produce BHET. Furthermore, t-BuP2 was found to have high regeneration performance, which could be recycled at least seven times without an apparent decrease in activity. [ABSTRACT FROM AUTHOR]

Controllable crystallization growth of perovskite films with excellent morphology and outstanding properties is a key and intractable problem for efficient and stable perovskite optoelectronic devices. However, the inhomogeneous inherent defects at the grain boundaries and interfaces make it difficult to uniformly release the residual stress during the growth process of perovskite films. Here, a molecular needle knitting strategy with dimethyl sulfoxide solvent as needles and polyoxyethylene molecular chains as threads was proposed to reveal the growth mechanism of perovskite–polymer composite films. Owing to the knitted net-structured cages synergistically constructed by the molecular needles and threads, the perovskite precursors can be uniformly assigned to each cage and nucleated evenly for the effective residual stress release under the formed spatial confinement effect. Compared with no confined cages, this obtained CsPbBr3 film via the molecular needle knitting strategy showed 50% enhanced photoluminescence quantum yield together with 40% improved stabilities. Based on this CsPbBr3 film and an UV LED chip (365 nm), we fabricated a high-stability and pure green LED lamp (528 nm). This work may open a way to achieve high quality fluorescent perovskite films and further extend their practical application in lighting and display fields. [ABSTRACT FROM AUTHOR]

Modern technologies are built on earth-abundant silicon. In this regard, the emerging autonomous micro/nanosystems urgently need to be compatible with the existing silicon-based infrastructure in terms of materials design and device assembly. Here, we for the first time demonstrate the incredible potential of silicon-based quantum dots (SiDs) for flexible and self-powered optoelectronics. The inclusion of an extremely small amount of luminescent SiDs enables a significant enhancement of piezoresponse of electrospun SiDs/polymer fabrics. Meanwhile, the hybrid fabrics retain the photoluminescent response of SiDs. Strikingly, the voltage output and current output of the hybrid fabrics reach 446 V cm−3 and 8.1 µA cm−3, respectively, which are almost 11 times and 19 times higher than those of state-of-the-art pristine fabrics, respectively. Moreover, the luminous fabric-based piezoelectric nanogenerator exhibits a highly durable and highly stable piezoresponse in more than 10 000 uninterrupted load cycles. As a proof of concept, in the scenario of a tennis match, the luminescent prototype device is further employed as a self-powered tactile sensor for real-time sports monitoring and athlete physiology monitoring. It shows ultrahigh mechanical sensitivity, flexibility, and reliability in sensing a broad range of strains and pressures. This study provides a new insight for accelerating the development of current and future self-powered micro/nanosystems. [ABSTRACT FROM AUTHOR]

Hydrogen peroxide (H2O2) is a multi-functional chemical for a range of industries, but the present H2O2 production requires complex processes, and leads to environmental pollution, etc. Solar water-splitting is one of the potential avenues to combine H2O and O2 into H2O2 through a cheap and clean way. Most of the photocatalysts involve multiple components and interfaces to improve the catalytic activity and energy conversion efficiency. However, it is difficult to regulate the photo-charge kinetics between the multi-interface catalyst, which hinders the practical application of photocatalysts. Here, we report a SnS2/In2S3 type II heterostructure modified by carbon dots (SnS2/In2S3/CDs) to highly improve the stability of sulfides and realize generation of H2O2 by the oxygen reduction reaction (ORR). Notably, in situ transient photovoltage measurements (TPV) were carried out to analyze the charge transfer process among SnS2, In2S3 and CDs. The optimal SnS2/In2S3/CD composite (n(Sn):n(In) = 50%) displays a prominent H2O2 production rate of 1111.89 μmol h−1 g−1 without any sacrificial agent under the conditions of normal pressure and neutral solution (pH = 7). The quantum efficiency (QE) of H2O2 production was calculated to be 3.9% under light (λ = 535 nm), and the solar energy conversion efficiency (SCC) was up to 1.02%, which is the highest known production of H2O2 from sulfides as photocatalysts. Our work provides a new way to regulate the photo-charge kinetics of the multi-interface catalyst using CDs to achieve the extremely efficient production of H2O2 by photocatalytic water-splitting. [ABSTRACT FROM AUTHOR]

Photocatalytic water splitting to produce hydrogen and hydrogen peroxide is the main goal of photocatalysis. However, the reactions of both are water based and thus, it is extremely challenging to conduct both processes on one catalyst. Herein, a function-switchable metal-free catalyst was designed and synthesized through the polycondensation of procyanidin and 4-methoxybenzaldehyde. Impressively, the catalyst developed here not only split water to produce hydrogen via a four-electron reaction process in the absence of air, but also generated hydrogen peroxide by preferentially reducing oxygen via a two-electron pathway in air. The production rates of hydrogen and hydrogen peroxide reached 252.02 and 1385.42 μmol h−1 g−1, respectively. Through in situ transient photovoltage tests and kinetic analysis, a clear and fundamental understanding of the highly efficient and switchable functions was acquired for this photocatalyst. This study highlights the unique behavior and provides an insight into the design of function-switchable catalysts and the regulation of catalytic reactions. [ABSTRACT FROM AUTHOR]

We developed a polymer-encapsulated DNase, n(DNase), which can efficiently accumulate in biofilm and expose the DNase to cleave the eDNA of the biofilm. CLSM and crystal violet staining results demonstrated effective biofilm disintegration (92.2%) when treated with n(DNase). This work demonstrated a general approach for coating matrix-dispersion enzymes to achieve biofilm disintegration and provided a promising strategy for treating biofilm-associated infections. [ABSTRACT FROM AUTHOR]

The production of hydrogen peroxide (H2O2) by photocatalytic water splitting has attracted much attention due to the wide application of H2O2 as a multi-functional chemical. Most of the present photocatalysts require sacrificial agents and/or noble metal cocatalysts. Herein, we report that phosphorus-doped porous carbon nitride (CPN), as a metal-free photocatalyst, achieves the photocatalytic water splitting via a two-channel pathway (water oxidation reaction and oxygen reduction reaction) with high H2O2 yield of 1968 μmol g−1 h−1 (highest yield in current records without sacrificial agent) under room temperature and normal pressure without sacrificial agent and cocatalyst. The quantum efficiency of the sole production of H2O2 was measured to be 1.57% under wavelength λ = 420 nm and the solar energy conversion efficiency was determined to be 0.43%. In the present reaction system, the concentration of H2O2 can be up to 0.171% (wt%) in a one-batch reaction using 80 mg CPN catalyst (in 15 mL oxygen saturated H2O) after 36 h under visible light illumination. H2O2 obtained by this metal-free catalyst without adding a sacrificial agent is more conducive to subsequent purification in industrial production. [ABSTRACT FROM AUTHOR]

Well-crystallized and uniform ScPO4·2H2O and ScPO4·2H2O:Ln3+ (Ln = Ce, Eu, Tb, Lu) nano/micro-crystals with multiform morphologies, such as sphere, hexagonal plate, diamond, four-angle star, butterfly-shaped and cuboid, have been successfully synthesized by a facile hydrothermal route without any surfactant molecules. XRD, FE-SEM, TEM, PL and kinetic decay were used to characterize the as-prepared products. The size and morphology of ScPO4·2H2O can be determined by the pH value, reaction time, reaction temperature, additive and doping of lanthanide ions. In particular, Ln3+ doping not only has a crucial role in the morphology of ScPO4·2H2O, but also affects its luminescence properties. The ScPO4·2H2O:Tb3+ and ScPO4·2H2O:Ce3+ samples display intense green and blue emissions, respectively. More importantly, the luminescence properties are closely related to morphologies and crystallinity. It can be found that the ScPO4·2H2O:Tb3+ sample with a hexagonal plate-like morphology possesses much higher emission intensity than those with other morphologies because of its larger anisotropic geometry. ScPO4:Ln3+ crystals will become promising candidates for a variety of applications in down/up-conversion luminescence, magnets, lasers, and bio-labeling. [ABSTRACT FROM AUTHOR]

Monodisperse ScF3 and NaScF4 nano-/micro-crystals were prepared by a simple solvothermal method. There were many important factors including the molar ratio of Na/F/(Sc + Ln) and Ln3+ doping to control the synthesis of the products. A phase transformation from monoclinic ScF3 to hexagonal NaScF4 was observed with different molar ratios of Na/F/Sc. Herein, the products doped with 1% Ln3+ (La–Lu, except Pm) demonstrated abundant phases, morphologies and sizes. Moreover, the products with different Lu3+ doping concentrations from 1% to 60% were prepared. The results revealed that different kinds of 1% Ln3+ (La–Lu, except Pm) and diverse concentrations of Lu3+ can modify the phase, morphology and size of the prepared products. A possible formation mechanism for the products with diverse morphologies is proposed. In addition, Ln3+-doped ScF3 or NaScF4 nano-/micro-crystals presented characteristic up/down-conversion fluorescence spectra. [ABSTRACT FROM AUTHOR]

Efficient polymeric adsorbents, including complexing membranes, attract increasing attention due to the global occurrence of micropollutants in water resources. Grafting polyhydroxy polymers onto a microporous membrane surface to prepare a complexing membrane for flow-through boron removal is also an emerging method. However, it remains a great challenge to develop efficient sorbents with both high capacity and high adsorption rate. In this work, hyperbranched polyols are grafted onto a polyacrylonitrile (PAN) membrane surface to prepare complexing membranes with high capacity and high adsorption rate, which utilize the structural characteristics of hyperbranched molecules to optimize the three-dimensional distribution of the chelating ligands. First, the PAN membrane was grafted with three hyperbranched polyethyleneimine (HPEI) macromolecules through a water mediated hydrolysis and amidation reaction in an autoclave followed by a ring opening reaction with glycidol. ATR-FTIR, XPS, FESEM and WCA methods were used to characterize the modified membranes. The results demonstrated that HPEI was successfully anchored onto the membrane surface and reacted with glycidol. Large quantities of hydroxyl groups were enriched on the surface of the membranes leading to rougher and superhydrophilic surfaces. The study on boron adsorption shows that the complexing membrane can absorb 3.2 mmol g−1 within only 4 min, which is superior to other reported sorbents. The adsorption isotherm can be described by the Langmuir model and the kinetic adsorption data fit very well with the pseudo-first-order expression. In addition, the boron adsorption can be completely regenerated for ten cycles of use by 15 min acid leaching without obvious degradation. The rapid boron removal and high regeneration are believed to benefit from the hyperbranched scaffold thanks to the high density and good accessibility of the ligands. [ABSTRACT FROM AUTHOR]

Photocontrolled reversible room temperature phosphorescence (RTP) emission engendered by the complexation of β-cyclodextrin (β-CD) and α-bromonaphthalene (α-BrNp) can be employed to address the threading and dethreading of the pseudorotaxane formed between β-CD and sodium 2-hydroxy-5-((4-nitrophenyl)diazenyl)benzoate (DAYR) in the ternary system in aqueous solution. [ABSTRACT FROM AUTHOR]

Developing efficient metal-free catalyst for the glycolysis of waste poly(ethylene terephthalate) (PET) with ethylene glycol (EG) has attracted increasing attention due to the demanding requirement for high-quality monomer used in regeneration. Herein, a new kind of efficient metal-free catalyst phosphazene base (t-BuP2) was developed through the combination of theoretical prediction and experimental verification approaches, which could achieve 100% conversion of PET and obtain BHET yield (92.7%) comparable to metal-based catalysts. The high efficiency of t-BuP2 comes from the facile generation of EG−, which has a strong ability to break the PET chain through a nucleophilic attack on the carbonyl group. t-BuP2 was selected as the catalyst based on the theoretical evaluation of the proton abstract ability of various bases through natural bond orbital analysis and reaction energy calculations, which could deprotonate EG barrierlessly to produce EG−. Next, the nucleophilic attack of EG− on the carbon atom of the carbonyl group in PET occurs, which greatly weakens the strong C–O bond on the PET chain. Then, the C–O bond was cleaved (rate-determining step) with the Gibbs activation energy and Gibbs reaction energy of 20.2 and −3.8 kcal mol−1, respectively, which was followed by the glycolysis step to produce BHET. Furthermore, t-BuP2 was found to have high regeneration performance, which could be recycled at least seven times without an apparent decrease in activity. [ABSTRACT FROM AUTHOR]

INHIBIT logic gates based on light-driven β-cyclodextrin pseudo[1]rotaxane were conveniently fabricated in aqueous solution utilizing induced circular dichroism (ICD) and photocontrolled reversible room temperature phosphorescence (RTP) as output addresses respectively.