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Reaction between 1,3,5-tris(triazol-1-ylmethyl)-2,4,6-trimethylbenzene (TTTMB), KSCN and Cu(NO3)2·3H2O results in {[Cu3(TTTMB)4 (SCN)6]·3.5H2O}n (1), a special three-dimensional coordination polyme...

In this work, a novel multichromic cationic coordination polymer, named [Zn4(BTC)3(bcbpy)2]·5H2O (1), based on a new flexible viologen ligand 1,1'-bis(3-cyanobenzyl)-[4,4'-bipyridine]-1,1'-diium (H2bcbpy·2Cl), Zn(NO3)2·6H2O and pyromellitic acid (H4BTC) was synthesized. Compound 1 has good photosensitive activity and can respond to sunlight at room temperature. The colour of compound 1 changes rapidly in response to UV light and blue ray irradiation within 5 s. We rarely obtained the crystal structures after irradiation under UV light and blue ray. At the same time, compound 1 shows the hydrochromism phenomenon when heated at 120 °C, and it also shows the ability of detecting aniline and NO2- under low-concentration conditions (10-4 M).

Recently, photocatalysts with a hollow mesoporous structure have drawn increasing interest owing to their extensive application in environmental protection. Herein, we prepared hollow mesoporous TiO2 nanospheres decorated with few layer 1T- and 2H- mixed phase MoS2 nanosheets via a template-based method and a hydrothermal reaction. The as-synthesized samples are of hollow mesoporous structure and high specific surface area, providing abundant mass transport and active sites for photocatalytic reaction. 1T-MoS2 in the mixed phase MoS2 mainly play the role as a bridge that transfers photoexcited electrons. Besides, the heterojunction between MoS2 and TiO2 can also efficiently restrain the recombination of photogenerated charge carriers in photocatalysts. As a consequence, under UV–vis light irradiation, the hollow porous TiO2/MoS2 presents a remarkable photocatalytic activity in rhodaming B degradation. Scavenger studies demonstrate that the primary active species in photocatalytic process are hydroxyl radicals. Moreover, a possible photocatalytic reaction mechanism has also been put forward.

Here, by a simple one-step in situ chemical reduction method, the AgxCuy alloy was tailored on the surface of mesoporous TiO2 (M-TiO2), therefore, a series of bi-functional mesoporous TiO2 nanohybrids (M-TiO2/AgxCuy) for both surface enhanced Raman scattering (SERS) detection and photocatalytic degradation of ampicillin (AMP) were achieved. The composition and structure of the nanohybrids were well characterized using XRD, TEM, XPS and HRTEM-EDS measurements. Results indicated that AgxCuy alloy was mainly attached around the pores of M-TiO2 which may generate more active sites than nonporous P25−Ag−Cu. Thus, the M-TiO2/AgxCuy nanohybrids could be used as efficient SERS substrates to sensitively monitor the AMP in water with lower detection limit (˜ 1 ppt) than P25−Ag−Cu. Besides, the M-TiO2/Ag3Cu1 nanohybrid also showed higher photocatalytic activities for the degradation of AMP under UV irradiation over the M-TiO2/Ag, the M-TiO2/Cu and the P25−Ag−Cu. This work provided a simple and effective approach to synthesize bi-functional nanohybrids for detection and degradation of organic contaminants in wastewater.

Development of photocatalysts with high activity and durability for hydrogen generation is extremely desired but still remains a great challenge currently. With Cu nanoparticles (Cu NPs) as a linker between TiO2 microsphere (TiO2 MS) and 5, 10, 15, 20-meso-tetra(4-carboxyphenyl)porphyrin (TCPP), a novel nano-micro hybrid (TiO2 MS-Cu-TCPP) was prepared via a facile method. By bridging TiO2 MS and TCPP with Cu NPs, the absorption and the electron transfer of TiO2 MS were greatly improved. When the TiO2 MS-Cu-TCPP was employed as the photocatalyst for hydrogen evolution, it exhibited higher activity and stability than those of the TiO2 MS, the TiO2 MS-Cu and the TiO2 MS-TCPP, TiO2 MS-Cu-CuTCPP and TiO2 MS-TCPP-Cu. The photocatalytic activity was enhanced for about 6 times with respect to that of the pristine TiO2 MS. The excellent performance for the nano-micro hybrid can be attributed to wide light absorption, more reactive sites, and facilitated interfacial electron transfer owing to the strong interaction between TiO2 and TCPP with Cu NPs as the linker and cocatalyst. Subsequently, a high and stable photocatalytic activity over the TiO2 MS-Cu-TCPP nano-micro hybrid was achieved, demonstrating the importance of interfacial modification to a semiconductor photocatalyst. This result gives us a new perspective of constructing special structures for efficient light utilization and electron transfer.

Development of highly active photocatalysts is one of the key topics for H2 production. Modifying the microstructure and exploring the electron transfer mechanism of the materials are very vital to achieve high-quality catalysts. Herein, by means of the bridging of rare-earth ions (Ln), a novel nanohybrid (GO–Ln–DPDPP) constructed of graphene oxide (GO) pillared with 5,15-diphenyl-10,20-di(4-pyridyl)porphyrin (DPDPP) was prepared by electrostatic interaction combined with coordination interaction. It was shown that the microstructure and morphology of the nanohybrid were greatly affected by the Ln introduced. Meanwhile, photoproduced electron transfer in the hybrid can be effectively promoted by the Ln implanted in the GO. Photocatalytic H2 production and the electron transfer mechanism were further explored. It was shown that, on the basis of the bridging of the Ln, lower interfacial resistance and higher separation of electron and hole caused by the strong interaction between DPDPP and GO were responsib...

The selective detection of methyl benzene (e.g. toluene and xylene) using oxide semiconductor-based gas/vapor sensors is highly desirable but limited by the low chemical reactivity of the benzene compounds. Exploiting p-type semiconductor oxides (e.g., NiO) which provide distinctive catalytic activities for methyl benzene detection is an essential approach. However, the intrinsic responses of p-type semiconductor oxides are often low. In this paper, high-performance toluene and xylene detection has been realized by a sensor based on novel p-p heterojunction NiGa2O4-NiO nanospheres. Construction of optimized p-p heterojunctions, which resulting from the rationally controlling of the NiGa2O4 content in NiGa2O4-NiO, leads to significantly promoted sensing properties for toluene and xylene detection. It is found that the sensor based on 50% NiGa2O4-NiO exhibits the best sensing performances. Its highest response (Rg/Ra = 12.7 to toluene; Rg/Ra = 16.3 to xylene) is almost 10 times higher than that of the pure NiO (Rg/Ra

Development of highly-active photocatalyst is of critical challenge for hydrogen production from water reduction, and optimizing the microstructure and the composition of the relative materials is very necessary to obtain the high-quality catalysts. Here, a novel self-adjusting structure of pompoms-like cadmium molybdate nano-micro hybrid stimulated by copper ions (Cu-CdMoO4) was achieved. It was found that the morphology and property of the CdMoO4 can be modulated greatly by the Cu. The optimal H2 generation amount for the hybrid was about 77.4 times higher than that of pure CdMoO4 under same conditions. The significantly improved activity is associated with wider light response, more active sites, and effective charge separation.

The development of highly active, stable and low-cost non-noble metal catalysts for hydrogen evolution reaction (HER) is extremely imperative. Multi-metal based electrocatalysts have recently become an emerging class of hydrogen evolution reaction (HER) electrocatalysts due to their excellent electrical conductivity and synergistic effects from metal atoms. However, the relationship between the cation and its intrinsic electrocatalytic properties in multi-metallic electrocatalysts is still not clear. Herein, we report a facile method for the preparation of surface-clean, phase-pure bimetallic (or multi-metallic) carbides through the solid reaction between metal salts and carbon nanotubes under an inert atmosphere. These multi-metallic carbides include molybdenum-based carbides (Co3Mo3C and Fe3Mo3C), tungsten-based carbides (Co6W6C, Ni6W6C and Fe6W6C) and trimetallic carbides (CoxFe3−xMo3C and CoxFe6−xW6C). Based on the synergistic effect of the metal atoms, the catalytic activities of the resulting bimetallic and trimetallic carbides are significantly improved compared to that of the single-metal carbides. The catalytic activity of the metal carbides decrease in the order of Co-based > Ni-based > Fe-based and Mo-based > W-based. Among them, Co3Mo3C has an optimized catalytic activity, offering a current density of 10 mA cm−2 at a low overpotential of 169 mV. Our study provides a controllable method for the preparation of the multi-metallic carbides and further justifies that the multi-metallic carbides are effective catalysts for HER.

A family of twelve monometallic diborides, containing transition metals from group IVB elements to group VIII elements, and Ni-W bimetallic diborides are synthesized via a molten salt-assisted method. Their trend in activity for the hydrogen evolution reaction is studied, with Ni-W bimetallic diborides acting as the most efficient, nonprecious electrocatalysts.

Formaldehyde is one of the most harmful environmental toxins, which should be less than 60 ppb indoors. Although some sensors, based on metal oxide semiconductors, are fabricated for the detection of formaldehyde, the sensing performance is not satisfactory yet. In this work, some rare earth metals are successfully introduced into In2O3 by a simple electrospinning method. The structure, composition and chemical state of the products are investigated by XRD, TEM, EDS, XPS, TPD and a Kelvin probe. And the sensor based on 5Y-doped In2O3 exhibits the highest response to formaldehyde. Moreover, this sensor also shows an ultra-low detection limit (50 ppb), a short response time (1 s) and good selectivity. It is believed that the improved sensing response and selectivity may originate from the elevated Fermi level and the increased surface basicity of In2O3, leading to the increase of chemisorbed oxygen on the surface and adsorption of formaldehyde.

Alzheimer's disease is the most common neurodegenerative disease, and has a high level of genetic heritability and population heterogeneity. In this study, we performed the whole-exome sequencing of Han Chinese patients with familial and/or early-onset Alzheimer's disease, followed by independent validation, imaging analysis and function characterization. We identified an exome-wide significant rare missense variant rs3792646 (p.K420Q) in the C7 gene in the discovery stage (P = 1.09 × 10−6, odds ratio = 7.853) and confirmed the association in different cohorts and a combined sample (1615 cases and 2832 controls, Pcombined = 2.99 × 10−7, odds ratio = 1.930). The risk allele was associated with decreased hippocampal volume and poorer working memory performance in early adulthood, thus resulting in an earlier age of disease onset. Overexpression of the mutant p.K420Q disturbed cell viability, immune activation and β-amyloid processing. Electrophysiological analyses showed that the mutant p.K420Q impairs the inhibitory effect of wild type C7 on the excitatory synaptic transmission in pyramidal neurons. These findings suggested that C7 is a novel risk gene for Alzheimer's disease in Han Chinese.

Noninvasive diagnosis of diabetes, using a biomarker, is an urgent clinical requirement to find and remedy diabetes early. Recently, acetone, a kind of ideal probing molecule, was used to diagnose diabetes which concentration increased greatly in exhaled breath of a Type 1 diabetic patients. However, the selective detection of acetone is difficult at ppb level, especially at a high humidity. In this study, Pt0.3Au0.7–In2O3, decorated with bimetallic catalyst, showed enhanced sensing performance towards trace acetone gas at a low operating temperature of 160 °C. In addition, even at high humidity atmosphere (up to 95% RH), its response to 1.8 ppm acetone (Type 1 diabetes patients) is about 44% higher than that of 0.9 ppm (normal human), which can be clearly distinguished for the diagnosis of Type 1 diabetes in a non-invasive and more accurate way. The excellent sensing performance indicates that bimetallic Pt–Au decoration is an effect way to improve the acetone sensing ability of In2O3.

By facilely pre-implanting Co[Formula: see text] ions in the graphene oxide, a novel 5,15-diphenyl-10,20-di(4-pyridyl)porphyrin pillared graphene oxide was fabricated by means of electrostatic interaction and coordination interaction. It was shown that the morphology and the structure of graphene oxide and pyridylporphyrin nanocomposite were modified by introducing Co[Formula: see text] ions on the interface between graphene oxide and pyridylporphyrin. Furthermore, it was found that the photocatalytic hydrogen evolution activity over the Co[Formula: see text] ions implanted in the graphene oxide and pyridylporphyrin nanocomposite was evidently higher than in the graphene oxide and pyridylporphyrin nanocomposite without Co[Formula: see text]. This confirmed that strong interaction and efficient electron transfer between pyridylporphyrin and graphene oxide are the important reasons for the enhanced photocatalytic activity for hydrogen evolution. Subsequently, this technique will be a simple and efficient approach to optimize the transfer pathway of photogenerated electrons and to improve photocatalytic performance by implanting metal ions in the interface of nanocomposites.

The cation substitutional doping of metal oxide semiconductors plays pivotal roles in improving the gas sensing performances, but the doping effect on surface sensing reaction is still not well understood. In this study, indium oxides doped with various heteroatoms are investigated to obtain in-depth understanding of how doping (or the resulting change in the electronic structure) alters the surface-absorbed oxygen chemistry and subsequent sensing process. The experimental results reveal that energy level of In2O3 can be modulated by introduction of these dopants, some of which (e.g., Al, Ga, and Zr) lead to the elevation of Fermi level, whereas others (e.g., Ti, V, Cr, Mo, W, and Sn) bring about relative drop in Fermi level. However, only the former can improve the response to formaldehyde, indicating a strong link between Fermi level and sensing properties. Mechanistic study suggests that the elevation of Fermi level increases energy level difference between oxide semiconductor and oxygen molecules and ...

Dye-sensitized solar cells (DSSCs) are performed using C3N4 post-treated TiO2 particles as photoanode materials. The photoanode materials were synthesized via a simple method by which a thin layer of C3N4 was coated onto the surface of TiO2 particles after the TiO2 was dipped in urea solution followed by calcination properly. The experimental results show that the photoelectric conversion efficiency of the TiO2 DSSCs is remarkably improved. The measurements of I-V characteristic along with the analysis of electrochemical impedance spectroscopy indicate that the C3N4 layer can expand the visible light absorption, suppress the recombination reaction of the e−-h+ pair and increase both the open circuit voltage and the short-circuit photocurrent density. The mechanism of the improved performance of TiO2 DSSCs by C3N4 coating coating is proposed. The post-treatment method recorded in this work can be easily operated and achieve an enhanced photoelectric performance of DSSCs.

A novel and highly active photocatalytic material, self-doped potassium niobate composite microflowers stimulated by noble-metal-free copper nanoparticles (Cu/K4Nb6O17), was achieved. The composition and structure of the composite microflowers were characterized by X-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM), and X-ray photoelectron spectroscopy (XPS). The results showed that Cu nanoparticles were evenly and closely loaded onto the flower slices of the composite microflowers. As testified by XPS, electrochemical impedance spectrum, and fluorescence spectrum, the presence of Cu in K4Nb6O17 microflowers quickened the self-doping of Nb4+, enhanced light absorption and the unsaturated defects as active sites, and improved the separation efficiency of electron/hole pairs, which led to excellent photocatalytic activity for hydrogen evolution over the composite microflowers. Subsequently, the optimal hydrogen generation rate for the composite microflowers was about 9 times h...

The orderly potassium niobate nanosheets/silver oxide (Ag2O) composite films with uniform morphology were achieved by layer-by-layer self-assembly combined with ultraviolet light irradiation. The composition, structure and morphology of the potassium niobate nanosheets/Ag2O composite films were studied by XPS, XRD and SEM. Furthermore, the films were used as a SERS probe to detect crystal violet molecules. The results showed that the potassium niobate nanosheets/Ag2O composite films were an active substrate for fast and sensitive detection of crystal violet with low concentration. The limit of detection by the films can reach 1 × 10−6 mol L−1. Both electromagnetic enhancement and chemical enhancement contributed to the enhanced SERS in the (potassium niobate nanosheets/Ag2O)4 films. Moreover, it was found that the films were relatively stable under light irradiation or heat treatment in a certain range.

Surface oxygen chemistry of semiconductor metal oxides is the basis for the sensing reaction between the preadsorbed surface oxygen and the target gases or organic vapors that are to be detected, and thus fundamentally determines their sensing performances. Herein, we, for the first time, identify a novel semiconductor spinel oxide, CdGa2O4, that has suitable surface oxygen chemistry and exhibits excellent selectivity and response toward formaldehyde. Moreover, we find that a cation off-stoichiometric CdGa2O4 spinel oxide decorated with a small amount of CdO nanocrystals can further improve the formaldehyde response, without losing the selectivity. This is based on the advantages of an increased amount of adsorbed oxygen in the Ga-rich environment, as well as heterojunctions between CdO nanoparticles and Ga-rich spinel oxide. Sensing performance (e.g., selectivity and response) of the material is much better than that of most reported nanostructured metal oxides used for formaldehyde detection. Our findin...

Photocatalysts with a hierarchically porous structure have attracted considerable attention owing to their wide pore size distribution and high surface area, which enhance the efficiency of transporting species to active sites. In this study, hierarchically meso-macroporous TiO 2 photocatalysts decorated with highly dispersed CdS nanoparticles were synthesized via hydrolysis, followed by a hydrothermal treatment. The textural mesopores and interconnected pore framework provided more accessible active sites and efficient mass transport for the photocatalytic process. The light collection efficiency was enhanced because of multiple scattering of incident light in the macropores. Moreover, the formation of a heterojunction between the CdS and TiO 2 nanoparticles extended the photoresponse of TiO 2 to the visible-light range and enhanced the charge separation efficiency. Therefore, the hierarchically meso-macroporous TiO 2 /CdS photocatalysts exhibited excellent photocatalytic activity for the degradation of rhodaming B under visible-light irradiation. Trapping experiments demonstrated that superoxide radicals ( O 2 − ) and hydroxyl radicals ( OH) were the main active species in photocatalysis. A reasonable photocatalytic mechanism of TiO 2 /CdS heterojunction photocatalysts was also presented.

Two ruthenium complexes [Ru(MeIm)4(bpy)]2+ (Ru1, MeIm = 1-methylimidazole, bpy = 2,2′-bipyridine) and [Ru(Im)4(bpy)]2+ (Ru2, Im = imidazole) with the same PF 6 − counter-ion but different lipophilicities were synthesized and characterized and as potent anticancer agents. The relationships between cellular uptake, localization and molecular action mechanisms of these complexes were elucidated. The results showed that Ru1 with higher logPo/w exhibited faster cellular uptake rates, but lower anticancer activity than Ru2. In addition, Ru1 predominantly accumulated in the mitochondria and cytoplasm, and induced G0/G1 cell cycle arrest, whereas the more hydrophilic Ru2 tended to localize and accumulate in the cell nucleus and mitochondria. Further mechanism studies indicated that Ru2 caused cell cycle arrest at S phase by regulating cell cycle related proteins and induced apoptosis in A549 cells through DNA damage, cellular ROS accumulation, activation of the caspase pathway and mitochondrial dysfunction.

The oxidation capacity and the quantity of chemisorbed oxygen are known to determine the extent of reaction with a target gas and thus deeply affect the sensing properties of a material. Therefore, to improve the reaction extent and enhance the sensing performance of a sensing material, a feasible and effective route is to increase the amount of chemisorbed oxygen on its surface. In this work, Ru species were successfully doped into the lattice of ultrathin In2O3 nanosheets. As a result, the oxygen vacancy enriched Ru-doped In2O3 not only exhibits a great ability to absorb oxygen on the surface, but also exhibits excellent catalytic ability for the selective oxidation of xylene. The 0.5% Ru–In2O3 sensor shows the best sensing performance for xylene detection, including ultrahigh response (Ra/Rg = 128.9 to 100 ppm), superior selectivity, low operating temperature (120 °C) and low detection limit (0.1 ppm). The excellent sensing properties make Ru-doped In2O3 a promising sensing material for xylene detection. Finally, we reveal that benzoic acid is the main intermediate for this sensing reaction.

By means of electrostatic interaction and coordination interaction, novel three-dimensional 1,2-di(pyridine-4-ly)ethyne (DPyE)/graphene oxide (GO) assemblies were fabricated with rare earth ions (Ln) as interfacial linkers. The structure, morphology and composition of the assemblies were characterized in detail. Furthermore, the photocatalytic activity for hydrogen production over the GO–Ln–DPyE assemblies was investigated. It was found that the photoactivity over GO–Ln–DPyE was distinctly higher than that over GO–DPyE without a bridging agent (rare earth ions), which indicated the important role of Ln in GO–DPyE. As evidenced by the photocurrent spectrum and electrochemical impedance spectrum, with rare earth ions as the interfacial linkers between GO and DPyE, it was important to define the mode of electron transfer and facilitate the separation of electron and holes, which was advantageous for improving the photocatalytic activity of GO–DPyE. The present study provides a new strategy for the construction of a GO-based heterostructure in order to improve its photocatalytic activity.

Hollow cobalt nickel oxide microspheres assembled by ultrathin porous nanosheets with tunable Co/Ni molar ratios have been successfully synthesized via a facile “self-template” method, taking solid bimetallic alkoxide microspheres as a precursor. The compositions and the sizes of the hollow cavities of cobalt nickel oxides can be easily controlled by the Co/Ni molar ratios and the size of bimetallic alkoxide microspheres, respectively. The electrochemical measurements indicate that the cobalt nickel oxide catalysts exhibit greatly enhanced oxygen evolution reaction (OER) activity in alkaline media, and Co2–Ni1–O microspheres with the optimal composition show the lowest overpotential (∼310 mV for 10 mA cm−2) and the smallest Tafel slope (57 mV per decade). This is attributed to the large electrochemically reactive surface and good charge conduction offered by the synergetic effects between their unique structural features and tunable compositions. The hollow cobalt nickel oxide microspheres may serve as promising noble-metal-free OER electrocatalysts to replace IrOx material, and the synthetic strategy that directs structural design can be applied to prepare other multifunctional materials.

A new type of nanohybrid (GO/THPP/PSA) was noncovalently constructed by anchoring 5, 10, 15, 20-tetrakis-(4-hydroxylphenyl)porphyrin (THPP) and 1-pyrenesulfonic acid hydrate (PSA) in graphene oxide (GO). The assembly mechanism of the nanohybrid was explored in detail. The results showed that THPP and PSA were attached in the GO by π–π stacking interaction and hydrogen bond. Compared with pure GO, GO/THPP or GO/PSA, the GO/THPP/PSA nanohybrid showed better photocatalytic activity for hydrogen evolution. The mechanism of electron transfer in the GO/THPP/PSA nanohybrid was investigated. It was shown that light absorption and separation of electron/hole pairs were improved dramatically due to wider light response and multi-channel electrons transfer in the hybrid. The results could initiate new ideas for constructing other graphene-based functionalized materials with high photocatalytic activity.

The development of high-efficiency and low-cost photocatalysts in photocatalytic H 2 evolution systems from water remains challenging. The substitution of a noble metal as the co-catalyst is still one of the important and meaningful issues in this field. Herein, we report a series of CaIn 2 S 4 catalysts combined with Ni 2 P, which acts as the co-catalyst, for boosting photocatalytic hydrogen evolution under visible light. The integrated system of the Ni 2 P/CaIn 2 S 4 composite exhibited high efficiency and durability, which were even higher than those of Pt decorated catalysts. The promoting effect of Ni 2 P can be ascribed to its excellent reductive ability and analogous metallic character, which can accelerate the transfer and consumption of the photo-generated electrons. Moreover, based on the surface photo-voltage technique and electrochemical tests, the unique mechanism of Ni 2 P for the movement of photo-generated charges during the photocatalysis process is proposed for the first time.

A simple template-free solvothermal route has been successfully developed to prepare iron-based fluoride nanostructures with controlled morphology and composition. Fe and F sources, reactant concentration, solvent composition and solvothermal reaction time play important roles in the control of the nanostructures and composition of the products. FeF3·0.33H2O hollow nanospheres exhibit high reversible capacities and good cycling performance when used as cathode materials for lithium ion batteries, and the hollow structure has an important impact on the electrochemical performance. In addition, the mesoporous structures within the materials provide an easily accessible system for lithium ion and electrolyte transportation diffusion. The small mesopores in the nanoparticles can also make the electrolyte and lithium ion further diffuse into the interior of the electrode materials and increase the electrolyte/electrode contact area.

Monitoring trace formaldehyde gas in air is of critical importance because of its high toxicity and threat to health, which is rather difficult at ppb level, especially at high humidity. Here, Pt-doped In2O3 composites consist of nanosheets with excellent formaldehyde sensing performance were prepared by a two-step method. The as-prepared 1 at% Pt-In2O3 composites give the best sensing performance toward formaldehyde gas with higher response, better selectivity and short response-recovery time at a low operating temperature (120 °C) compared to the pure In2O3. Its response is about 3 times as large as that of pure In2O3 to 10 ppm formaldehyde at 120 °C. The response time of the 1 at% Pt-In2O3 composite is less than 2 s and its recovery time is 51 s. In particular, it can detect down to 60 ppb formaldehyde in a wide range of relative humidity (25%–90% RH). The enhanced sensing properties of the composites should be attributed to the high catalytic activity of Pt/PtO2 nanoparticles decorated on the surface of In2O3 hollow microspheres and the Schottky barrier between Pt species and In2O3.

IrO2-loaded porous foam-like Ga1.4In0.6O3 nanofibers with ultrathin pore walls were synthesized via a simple electrospinning and impregnation method for the detection of formaldehyde. This gas sensor based on IrO2-loaded Ga1.4In0.6O3 nanofibers showed excellent sensitivity and selectivity towards trace formaldehyde. Especially, the response of the gas sensor based on 1% IrO2-Ga1.4In0.6O3 nanofibers is as high as 46 towards 10 ppm formaldehyde, while it is only 7 for the gas sensor based on Ga1.4In0.6O3. Moreover, the gas sensor based on 1% IrO2-Ga1.4In0.6O3 exhibited remarkable selectivity towards formaldehyde. The high sensitivity and good selectivity of IrO2-loaded porous Ga1.4In0.6O3 nanofibers could be attributed to the specific catalytic activity of IrO2, the unique composition and the ultrathin structure of Ga1.4In0.6O3.

The concentration of acetone in exhaled breath is an efficient indicator for the diagnosis of diabetes. However, it is difficult to detect acetone in exhaled breath due to the extremely low acetone concentration, rather complex composition and very high humidity. Herein, we report Pt-decorated foam-like Ga-In bimetal oxide nanofibers (Pt-GIO) for trace concentration acetone detection. We found that the Pt-GIO based sensor exhibits enhanced sensing response towards acetone compared with that of Ga-In bimetal oxide (GIO), due to the formation of Schottky contact between Pt and n-type GIO, leading to the increased chemisorbed oxygen. As a result, the Pt-GIO based sensors gives a high response (3.2), short response time (13 s) to 1.8 ppm acetone and very low detection limit (300 ppb). The Pt-GIO sensor also gives good stability and is nearly insensitive to moisture in the range of 40% RH to 95%. These advantages including high response, low detection limit, short response time and high moisture resistance endow Pt-GIO a promising sensing material for acetone detection in exhaled breath.

The engineering of an efficient electrochemical sensor based on a bismuth sulfide/reduced graphene oxide (Bi2S3/rGO) composite to detect ascorbic acid (AA) is reported. The Bi2S3 nanorods/rGO composite was synthesized using a facile hydrothermal method. By varying the amount of graphene oxide (GO) added to the synthesis, the morphology and size of Bi2S3 nanorods anchored on the surface of rGO can be tuned. Compared to a bare glassy carbon electrode (GCE), the GCE modified with Bi2S3/rGO composite presented enhanced electrochemical performance, which was attributed to the optimal electron transport between the rGO support and the loaded Bi2S3 as well as to an increase in the number of active catalytic sites. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) analysis of Bi2S3/rGO/GCE demonstrate that the active Bi2S3/rGO layer on GCE plays an important role in the electrochemical behavior of the sensor. In particular, the Bi2S3/rGO/GCE sensor shows a wide detecting range (5.0–1200 μM), low detection limit (2.9 µM), good sensitivity (268.8 μA mM−1 cm−2), and sufficient recovery values (97.1–101.6%) for the detection of ascorbic acid.

Highly active and durable catalysts are imperative for the development of alcohol oxidation research. Herein, a Ni/NiO-C catalyst with hollow NiO crystal can be used in ethanol oxidation. The hollow NiO nanoparticles are absolutely coated in the amorphous carbon and the generated NiO crystal remarkably raises the electrocatalytic performances of catalysts. Among all samples, the Ni/NiO-C3 catalyst shows the highest current density in 0.5 M ethanol solution. This is mainly derived from the synergistic effect of the crystallographic form, carbon coating, and hollow structure. Besides, the reaction mechanism of Ni/NiO-C3 electrode is controlled by charge transfer in high-concentration ethanol. With the concentration of ethanol decreased, a diffusion control mechanism is observed on Ni/NiO-C3 electrode. The attenuation rate of current density is only 0.1% after 3600 s by chronoamperometry in 0.1 M ethanol aqueous solution, indicating that the Ni/NiO-C3 electrode has a superior stability. Moreover, Ni/NiO-C3 electrode exhibits an rapid current response in 0.1 mM ethanol solution and a linear relationship between 0.69 and 40.17 mM, which provides a new idea for the research of fuel cell type ethanol sensor.

The hydrogen evolution reaction (HER) is involved in energy-intensive water- and chlor-alkali electrolyzers, and thus, highly active and stable HER electrocatalysts in alkaline media are needed. Titanates, a family of representative two-dimensional materials with negatively charged main layers, are chemically and structurally stable under strongly basic conditions, but they have never been shown to have electrocatalytic activity for HER. Herein, we report that intercalating 3d metal cations, including Fe

To guarantee the human health, it is important to monitor the amount of formaldehyde in air. However, it is difficult to detect formaldehyde at low concentration level. Here, WO x clusters decorated In 2 O 3 nanosheets were synthesized for the first time via a simple and convenient impregnating method. The sensors based on the above WO x /In 2 O 3 composites show excellent sensing performance to trace formaldehyde gas at a relative low operating temperature (170 °C). The gas sensor based on 4 wt% WO x /In 2 O 3 exhibits the lowest detection limit ( i.e. 0.1 ppm), short response time (1 s) and acceptable recovery time (67 s). Furthermore, the response value of 4 wt% WO x /In 2 O 3 composite sensor is about twice as high as that of the sensor based on pure In 2 O 3 . It is believed that the enhanced sensing performance can be predominantly attributed to the additional active sites induced by the formation of WO x -In 2 O 3 heterojunction between WO x nano-clusters and In 2 O 3 nanosheets.

Porous LiMn2O4 microsheets with micro-nanostructure have been successfully prepared through a simple carbon gel-combustion process with a microporous membrane as hard template. The crystal structure, morphology, chemical composition, and surface analysis of the as-obtained LiMn2O4 microsheets are characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscope (XPS). It can be found that the as-prepared LiMn2O4 sample presents the two-dimensional (2-D) sheet structure with porous structure comprised with nano-scaled particles. As cathode materials for lithium-ion batteries, the obtained LiMn2O4 microsheets show superior rate capacities and cycling performance at various charge/discharge rates. The LiMn2O4 microsheets exhibit a higher charge and discharge capacity of 137.0 and 134.7 mAh g−1 in the first cycle at 0.5 C, and it remains 127.6 mAh g−1 after 50 cycles, which accounts for 94.7% discharge capacity retention. Even at 10 C rate, the electrode also delivers the discharge capacity of 91.0 mAh g−1 after 300 cycles (93.5% capacity retention). The superior electrochemical properties of the LiMn2O4 microsheets could be attributed to the unique microsheets with porous micro-nanostructure, more active sites of the Li-ions insertion/deinsertion for the higher contact area between the LiMn2O4 nano-scaled particles and the electrolyte, and better kinetic properties, suggesting the applications of the sample in high-power lithium-ion batteries.

A novel composite with special structure and excellent performance, 5,10,15,20-tetrakis(4-hydroxyphenyl) porphyrin (THPP) coated Cu2O nanoparticle (Cu2O/THPP), was facilely prepared by a simple method. UV–vis spectra, FTIR and fluorescence spectra were used to explore the interaction mechanism between THPP molecule and Cu2O nanoparticle. The results demonstrated that the center of the THPP macrocycle could coordinate with Cu2O, besides hydrogen bond and/or electrostatic interaction between peripheries of THPP macrocycle and Cu2O. Furthermore, photocatalytic hydrogen evolution performance of the composite was investigated. The composite displayed more excellent performance for hydrogen evolution than that of pure THPP, pure Cu2O or 5,10,15,20-tetraphenylporphyrin (TPP) coated Cu2O nanoparticle (Cu2O/TPP). By means of fluorescence spectra, electrochemical impedance spectra and photoelectronic performance measurement, the mechanism of electron transfer in the composite was explored. The results showed that the strong synergetic interaction caused by the special combination mode between THPP and Cu2O can quicken the transfer of photo-generated electrons, and was very favorable to improve the performance of the Cu2O/THPP composite.

Nest-like TiO 2 hollow microspheres composed of nanowires have been successfully synthesized via a simple process including hydrothermal treatment and calcination. The hydrothermal treatment time plays important roles in the morphologies and crystallographic structures for the final products. The obtained nest-like TiO 2 hollow microspheres gives a reversible capacity of 228 mAh g −1 at 0.5C rate. Furthermore, the nest-like TiO 2 hollow microspheres could possess relatively high reversible capacities even at higher charge/discharge rates. The reversible capacities of approximately 210, 191, 166, 150 and 130 mAh g −1 are obtained at 1C, 2C, 5C, 10C and 20C, respectively. The superior electrochemical performance of hollow TiO 2 microspheres composed of nanowires is mainly related to its efficient hierarchical nanostructures.

Great efforts have been devoted on the detection of the volatile organic compounds indoor for human health. The detection of formaldehyde is one of the most important and popular issues for the wide usage of formaldehyde and its toxic. However, it is a challenge to monitor trace gaseous formaldehyde at lower working temperature. Herein, we present a sensor with a significantly improved sensing response and dramatically decreased operating temperature based on porous PtO 2 /SnO 2 microspheres. And the PtO 2 /SnO 2 -5 mol% composite shows the most outstanding sensing performance among all products. What’s more, the above sensor can detect gaseous formaldehyde in the ppb level (100 ppb) at low operating temperature (100 °C). The excellent sensing performance should be attributed to the high catalytic activity of PtO 2 nanoparticles decorated on the surface of SnO 2 microspheres and the porosity of the composite.

Controllable assembly of the hybrids composed of various types of nanoscale objects provides new opportunities for material fabrication. Herein, the tunable bi-functionalities of fluorescence and surface enhanced Raman scattering (SERS) signals were collected by the assembled composites of gold nanoparticles (AuNPs)/glycine derivatives (Gn, n = 0, 3, 4, 5, 6 and 9)/graphene quantum dots (GQDs). The composition and structure of the AuNPs/Gn/GQDs composites were characterized by Fourier-transform infrared (FT-IR) spectroscopy and high resolution transmission electron microscope (HRTEM). Results indicated that the fluorescence and SERS response could be tuned effectively by changing the chain length of Gn. Also, the AuNPs/Gn/GQDs composites could be used in a wide pH range and exhibited good stability at room and physiological temperatures. Moreover, the AuNPs/Gn/GQDs composites displayed low cytotoxicity in A549 cells, and the cell viability was found to be above 90% at concentrations ranging from 6.42 to 200 μg/mL, which made AuNPs/Gn/GQDs composites very attractive for biological imaging applications in vivo. Keywords: Gold nanoparticles, Graphene quantum dots, Bridged composite, Bi-functionality, Biological imaging

Nitric oxide (NOx, including NO and NO2) is one of the most dangerous environmental toxins and pollutants, which mainly originates from vehicle exhaust and industrial emission. The development of sensitive NOx gas sensors is quite urgent for human health and the environment. Up to now, it still remains a great challenge to develop a NOx gas sensor, which can satisfy multiple application demands for sensing performance (such as high response, low detection temperature, and limit). In this work, ultrathin In2O3 nanosheets with uniform mesopores were successfully synthesized through a facile two-step synthetic method. This is a success due to not only the formation of two-dimensional (2D) nanosheets with an ultrathin thickness of 3.7 nm based on a nonlayered compound but also the template-free construction of uniform mesopores in ultrathin nanosheets. The sensors based on the as-obtained mesoporous In2O3 ultrathin nanosheets exhibit an ultrahigh response (Rg/Ra = 213) and a short response time (ca. 4 s) towa...

The overall water splitting into hydrogen and oxygen is one of the most promising ways to store intermittent solar and wind energy in the form of chemical fuels. However, this process is quite thermodynamically uphill, and thus needs to be mediated simultaneously by efficient hydrogen evolving and oxygen evolving catalysts to get any feasible output from it. Herein, we report the synthesis of such a catalyst comprising ultrasmall NixCo3−xS4-decorated Ni3S2 nanosheet arrays supported on nickel foam (NF) via a partial cation exchange reaction between NF-supported Ni3S2 nanosheet arrays and cobalt(II) ions. We show that the as-prepared material, denoted as NixCo3−xS4/Ni3S2/NF, can serve as a self-standing, noble metal-free, highly active and stable, bifunctional electrocatalyst for the two half reactions involved in the overall water splitting: the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER). Furthermore, we demonstrate that a high-performance electrolyzer for the overall water splitting reaction can be assembled by using NixCo3−xS4/Ni3S2/NF as the electrocatalyst at both the cathode and the anode sides of the electrolyzer. This electrolyzer delivers water-splitting current densities of 10 and 100 mA/cm2 at applied potentials of 1.53 and 1.80 V, respectively, with remarkable stability for >200 h in both cases. The electrolyzer's performance is much better than the performances of electrolyzers assembled from many types of other bifunctional electrocatalysts as catalyst couple. Moreover, the overall performance of the electrolyzer is comparable with the performances of electrolyzers containing two different, benchmark, monofunctional HER and OER electrocatalyst couple (i.e., Pt/C-IrO2).

A noble-metal-free reduced graphene oxide composite, copper nanoparticles (Cu NPs) loaded reduced graphene oxide (Cu/RGO), was prepared via a one-step in-situ reduction method. Furthermore, the catalytic activity of the composite for reduction of 4-nitrophenol (4-NP) was investigated. The results showed that the composite was a highly efficient, stable and low-cost catalyst for transformation of 4-NP. In the composite, Cu NPs acted as the cocatalyst and the RGO acted as the substance of electron transfer. The catalytic mechanism was also suggested. Copper nanoparticles loaded reduced graphene oxide (Cu/RGO) was prepared via a one-step in-situ reduction method. The Cu/RGO composite exhibited high catalytic activity and good recycle stability for treatment and transformation of 4-nitrophenol. Compared with the similar catalysts, the Cu/RGO composite is a cheaper, stable and highly efficient in practical application.

Using the polyoxometalate (PW) as a photoreduction agent, the uniform PW/reduced graphene oxide (RGO)/Ag film was fabricated via electrostatic self–assembly followed by UV reduction. Importantly, the film can be used as a surface enhanced Raman scattering probe for the selective detection of trace formaldehyde. Compared with those of the PW/RGO film and the PW/Ag film, the PW/RGO/Ag film displays the higher sensitivity, and the detection limit for formaldehyde can reach about 10−8 mol L−1.

N-doped carbon encapsulated nickel nanoparticles (NiNC) are prepared from mixtures of nickel salt, glucose and urea by a simple heating protocol. A higher viscosity of the mixture inhibits the migration of Ni species such that highly dispersed and very small Ni nanoparticles form during heat treatment. The sizes of the Ni nanoparticles can be controlled by adjusting the composition of the raw mixtures. The optimized sample of NiNC-4 contains Ni nanoparticles of 2.02 nm in size which afford a large metal surface area of 400.7 m 2 g −1 and a high nitrogen content of 7.21 at%. An ultra-high current density of 327 mA cm −2 is achieved in 0.1 M NaOH electrolyte containing 1 M ethanol using NiNC–4 as the electrocatalyst. NiNC-4 electrodes also exhibit a good long-term cycling stability. After 500 cycles, 89% of the initial current density is sustained in 0.1 M NaOH electrolyte containing 0.5 M ethanol. 96.8% of the initial current density is retained by moving the NiNC–4 electrode into fresh 0.1 M NaOH solution with 0.5 M ethanol after 500 cycles. The excellent electrocatalytic properties of NiNC–4 for ethanol oxidation stem from the synergistic effect of the porous carbon substrate, abundant N-containing groups and the small nickel nanoparticle size.

More active sites and high conductivity are two effective ways to improve the activity of non-noble metal electrocatalysts. Herein, we present a facile electrostatic spinning technique to synthesize highly dispersed CoSe 2 nanoparticles on three-dimensional nano-netlike carbon fibers through simple thermal treatment of polyacrylonitrile fibers containing Co ions (Co 2+ -PANF) and subsequent in-situ selenization. Moreover, we show that the resulting material (denoted as CoSe 2 -CFN) can serve as highly active, efficient and stable non-precious metal electrocatalyst for HER in acidic media. This material achieves a current density of 10 mA/cm 2 at an overpotential of 133 mV with a loading amount of the active material CoSe 2 about 0.128 mg/cm 2 , which is lower than that of the reported CoSe 2 -based materials. Meanwhile, CoSe 2 -CFN exhibits excellent catalytic stability for at least 20 h and gives nearly 100% Faradaic yield. The excellent hydrogen evolution reaction performance is due to the highly dispersed CoSe 2 nanoparticles providing more active sites as well as the high electrical conductivity of the carbon fibers.

The development of efficient and inexpensive water splitting electrocatalysts is essential for the large-scale production of hydrogen. Herein, we show that a novel nanohybrid with CoS nanosheets vertically grown on carbon cloth (CoS/CC) can be used as an efficient self-supported hydrogen-evolving cathode for water splitting over a wide pH range. This material affords a current density of 10 mA/cm 2 at a small overpotential of 192 mV and 212 mV in basic and acidic media, respectively, along with a long-term stability for over 50 h. The unique 3D structure constructed by the vertically arranged nanosheets and the intimate contact between the CoS nanosheets and the underlying conductive carbon are believed to be responsible for the excellent catalytic performance.

Transition metal spinel semiconductors, with a general formula of AB2O4, have been shown as a promising group for gas sensor applications. This paper reports a simple and effective electrospinning method to systematically prepare mesoporous MGa2O4 (M Ni, Cu, Co) nanofibers. It is found that gas sensing reaction process of the materials is decisively influenced by transition metal M(II)-ions. The gas response tends to decrease in the order of NiGa2O4 > CuGa2O4 > CoGa2O4. In addition, NiGa2O4 and CoGa2O4 show p-type behaviors, and CuGa2O4 shows an n-type behavior. Further analysis reveals that charge carrier hopping (e− hopping or h+ hopping) processes between different valent metal cations, which is mainly dominated by octahedral sites of spinel, are responsible for the conductivity type, the surface redox reaction and thereby the gas sensing properties.

With 5,10,15,20- meso -tetra(4-carboxyphenyl)porphyrin (TCPP) and cuprous oxide nanosheet as main reactants, a novel composite (TCPP/Cu 2 O) was prepared via a facile method. The assembly mechanism of TCPP and Cu 2 O was investigated by UV–vis spectroscopy and FTIR. The results indicated that not only peripheries of TCPP but also the central of TCPP macrocycle interacted with Cu 2 O. Furthermore, with the obtained composite as the photocatalyst, the photocatalytic activity for hydrogen production was investigated. The composite showed more excellent performance for hydrogen production than that of pure TCPP or pure Cu 2 O, and also higher than that of 5,10,15,20- meso -tetraphenylporphyrin (TPP)/Cu 2 O composite. By means of fluorescence spectra, electrochemical impedance spectra and photoelectronic performance measurement, the mechanism of electron transfer in the composite was explored. The results showed that the introduction of TCPP can enhance the light absorption of Cu 2 O, and the strong interaction between TCPP and Cu 2 O can quicken the transfer of photo-generated electrons. It hoped that this work can open up a new perspective for the assembly and application of dye-functionalized semiconductor nanoparticles.

The design of appropriate composite materials with unique surface structures is an important strategy to achieve ideal chemical gas sensing. In this paper, efficient and selective detection of formaldehyde vapor has been realized by a gas sensor based on porous GaxIn2-xO3 nanofibers assembled by small building blocks. By tuning the Ga/In atomic ratios in the materials, crystallite phase, nanostructure, and band gap of as-obtained GaxIn2-xO3 nanofibers can be rationally altered. This further offers a good opportunity to optimize the gas sensing performances. In particular, the sensor based on porous Ga0.6In1.4O3 nanofibers assembled by small nanoparticles (∼4.6 nm) exhibits best sensing performances. Toward 100 ppm formaldehyde, its highest response (Ra/Rg = 52.4, at 150 °C) is ∼4 times higher than that of the pure In2O3 (Ra/Rg = 13.0, at 200 °C). Meanwhile, it has superior ability to selectively detect formaldehyde against other interfering volatile organic compound gases. The significantly improved sensi...

Three new organic–inorganic hybrid compounds based on [SiNb12V2O42]12− have been obtained under hydrothermal conditions and characterized by IR, XRD, and single crystal X-ray diffraction analysis. Single crystal X-ray analysis reveals that [Cu(en)2]4[Cu(en)2(H2O)2]2[SiNb12V2O42]·14H2O (1) is constructed from [SiNb12V2O42]12− and two kinds of copper complexes, polyoxoanions in [Cu(en)2]2[Cu(en)2(H2O)]4[SiNb12V2O42]·4H2O (2) and [Cu(en)2(H2O)2]4[Cu(en)2(H2O)]2[SiNb12V2O42]·11H2O (3) are identical to compound 1, but the copper complex combinations of these two compounds are different from that of compound 1. Therefore, the final structures of the three are different from one another. All the three compounds are excellent catalysts for the epoxidation of styrene. In addition, we also synthesized an isopolyniobate K6H2Nb6O19·17H2O (4), which exhibits a 3-D structure constructed from [Nb6O19]8− and potassium clusters.