Latest ArticlesAs a key biomarker for noninvasive diagnosis of diabetes, the selective detection of trace acetone in exhaled gas using a portable and low-cost device remains a great challenge. Semiconductor metal oxide (SMO) based gas sensors have drawn signification attention due to their potential in miniaturization, user-friendliness, high cost-effectiveness and selective real-time detection for noninvasive clinical diagnosis. Herein, we propose a one-pot solvent evaporation induced tricomponent co-assembly strategy to design a novel ordered mesoporous SMO of silica-implanted WO3 (SiO2/WO3) as sensing materials for trace acetone detection. The controlled co-assembly of silicon and tungsten precursors and amphiphilic diblock copolymer poly(ethylene oxide)-block-polystyrene (PEO-b-PS), and the subsequent thermal treatment enable the local lattice disorder of WO3 induced by the amorphous silica and the formation of ordered mesoporous SiO2/WO3 hybrid walls with a unique metastable ε-phase WO3 framework. The obtained mesoporous SiO2/WO3 composites possess highly crystalline framework with large uniform pore size (12.0–13.3 nm), high surface area (99–113 m2/g) and pore volume (0.17–0.23 cm3/g). Typically, the as-fabricated gas sensor based on mesoporous 2.5%SiO2/WO3 exhibits rapid response/recovery rate (5/17 s), superior sensitivity (Rair/Rgas = 105 for 50 ppm acetone), as well as high selectivity towards acetone. The limit of detection is as low as 0.25 ppm, which is considerably lower than the thresh value of acetone concentration (>1.1 ppm) in the exhaled breath of diabetic patients, demonstrating its great prospect in real-time monitoring in diabetes diagnosis. Moreover, the mesoporous 2.5%SiO2/WO3 sensor is integrated into a wireless sensing module connected to a smart phone, providing a convenient real-time detection of acetone.
A facile visible-light-induced 1,2,3,5-tetrakis(carbazol-9-yl)-4,6-dicyanobenzene (4CzIPN) catalyzed four-component reaction of alkenes, quinoxalin-2(1H)-ones, P4S10 and alcohols has been developed at room temperature. This tandem reaction provides an efficient strategy for the construction of various phosphorodithioate-containing quinoxalin-2(1H)-ones with moderate to good yields by using air (dioxygen) as the green oxidant. Experimental studies revealed a radical process was involved in this photochemical reaction.
Defects can strongly affect the lattice, strain, and electronic structures of nanomaterials photocatalysts, like a double-edged sword of both positive significance and negative influence on photocatalytic performances. To date, most studies into defects only partially elucidated their beneficial or detrimental roles in photocatalysis. However, a quantitative understanding of the photocatalytic performances modulated by defect concentration still needs to be discovered. Here, a series of TiO2−X mesoporous spheres (MS) with different oxygen vacancy concentrations for photocatalytic applications were prepared by high-temperature chemical reduction. The link between oxygen vacancy concentration and photocatalytic performance was successfully established. The localization of carriers dominated by the Stark effect is first enhanced and then weakened with increasing oxygen vacancy concentration, which is a crucial factor in explaining the double-edged sword role of defect concentration in photocatalysis. As the reduction temperature rises to 300 ℃, carrier localization dominated by the quantum-confined Stark effect maximizes the separation ability of photo generated electron hole pairs, thus exhibiting the best catalytic performance for photocatalytic hydrogen production and the degradation of organic pollutants, as demonstrated by a hydrogen evolution rate of 523.7 µmol g-1 h-1 and a ninefold higher RhB photodegradation rate compared to TiO2 MS. The work offers excellent flexibility for precisely constructing high-performance photocatalysts by understanding vacancy engineering.
A novel Ce-containing poly(tungstobismuthate) Cs18Na8H20[Ce3(H2O)10W8Bi4O28(B-α-BiW9 O33)4]2·64H2O (1) has been synthesized by a facile one-pot self-assembly reaction strategy. Its structural characterization is realized by virtue of single-crystal X-ray diffraction, infrared spectroscopy, powder X-ray diffraction and thermogravimetric analysis. The polyoxoanion of 1 is an octameric architecture consisting of two tetrameric entities [Ce3(H2O)10W8Bi4O28(B-α-BiW9O33)4]23− linked by two CeOW bonds, and adjacent polyoxoanions are further combined together by means of Ce3+ linkers, resulting in an infinite 1D chain architecture. Compound 1 is the currently largest tungstobismuthate, and also represents the first example of lanthanide-encapsulated tungstobismuthate exhibiting an extended structure. Furthermore, compound 1 as a heterogeneous catalyst, exhibits high activity for the oxidative decontamination of a sulfur mustard simulant, 2-chloroethyl ethyl sulfide (CEES) into 2-chloroethyl ethyl sulfoxide (CEESO).
In core-shell silver nanoclusters, the control of core structure presents a more formidable challenge compared to that of the shell structure. Here, we report the successful synthesis and characterization of four distinct silver thiolate nanoclusters [MS4@Ag12@Ag46S24(dppb)12] (M = Mo or W), each incorporating a cup-like [MS4@Ag12]2+ kernel. These nanoclusters were meticulously prepared using (NH4)2MoS4 or (NH4)2WS4 as both a template and a controlled source of S2− ions. Remarkably, we have observed a unique configuration within these eight-electron superatomic Ag58 nanoclusters, where the zero-valent Ag atoms reside exclusively within the inner [MS4@Ag12]2+ kernel. This stands in contrast to other superatomic clusters possessing an Ag(0) core. Notably, the introduction of phenyl-containing compounds during the synthesis process induced a transformation in the space group symmetry from C2/c to I4. This transformative effect was found to originate from the interplay between adjacent 1,4-bis(diphenylphosphino)butane (dppb) ligands, which facilitated enhanced emission through aggregation-induced intermolecular interactions, specifically C−H···π interactions. Collectively, our findings contribute substantively to the understanding of the intricate relationship between nanocluster structures and their corresponding properties, shedding light on the crucial roles played by templates and diphosphine ligands in this context.
Polymeric carbon nitride (PCN) has garnered increasing attention as a metal-free photocatalyst with a suitable band gap. In efforts to enhance its photocatalytic performance, researchers have examined various PCN materials, including poly(heptazine imide) (PHI) and poly(triazine imide) (PTI), two isomers within the PCN family that exhibit distinct and superior photocatalytic activity compared to other forms. The challenge, however, lies in the common practice among researchers to categorize PHI and PTI along with other PCN types under the overarching term "g-C3N4, " which significantly impedes optimization efforts. The objective of this review is to provide comprehensive insights into the structural features, photoelectrochemical properties, and effective characterization methods employed for distinguishing between PHI and PTI materials. The review also summarizes various optimization strategies, such as crystallinity adjustments, defect engineering, morphology control, constructing heterojunction, and atomic-level metal loading dispersion, to elevate the photocatalytic activity of PHI and PTI, in addition to summarizing the history of carbon nitride development. Furthermore, this review highlights the primary applications of PHI and PTI, encompassing nitrogen fixation, biomass conversion, organic synthesis, CO2 reduction, pollutant degradation, H2O2 production, and photocatalytic water splitting. Lastly, the prospects and challenges associated with further advancing PHI and PTI are thoroughly examined.
Understanding the role of perovskite surface passivators in hot carriers transfer dynamics is important to develop highly efficient perovskite solar cells (PSCs). In this work, we have designed and synthesized a naphthalimide-based organic small molecule (NCN) for perovskite surface defect passivator. We reveal that the introduction of NCN not only reduces the density of perovskite defect-state, but also promotes hot carriers (HCs) cooling in perovskite through the transient absorption spectroscopy measurements. Fast HCs cooling permits HCs transfer from perovskite layer into NCN layer, thus resulting in the decreased charge-carrier recombination in NCN-treated device. As expected, the power conversion efficiency (PCE) of PSCs with NCN is enhanced to 22.02% from 19.95% for the control device. The findings are relevant for developing highly efficient PSCs.
Since the appearance of Rochelle salt, ferroelectrics have received extensive attention from researchers due to they are playing an important role in sensors, memories, mechanical actuation, and so on. In recent years, with the rapid development of molecular ferroelectrics, high-performance molecular ferroelectrics have become effective complement to inorganic ferroelectrics. However, compared with inorganic ferroelectrics, the family of molecular ferroelectrics is relatively scarce, and exploring high-performance ferroelectric materials through new synthesis strategies has become the trend of molecular ferroelectrics. Here, we successfully transformed non-polar material 1 (2-H2PCA)2(H2O)CdCl6 (2-H2PCA = 2-picolylamine cation) into polar material 2 (2-H2PCA)2CdCl6 by single-crystal to single-crystal transformation (SCSCT). Meanwhile, 2 exhibits clear ferroelectricity with a high-temperature Tc of 378 K, a Ps of 1.18 µC/cm2 at 300 K. This work not only realizes the purpose of synthesizing ferroelectrics by forming polar structures by SCSCT, but also realizes the reversibility of SCSCT, which provides ideas for the construction and exploration of new molecular ferroelectrics.
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