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Crystal defects are crucially important in semiconductor photocatalysis. To improve the reactivity of photocatalysts and attain desirable solar energy conversion, crystal defect engineering has gained considerable attention in real catalysts. Herein, we engineered crystal defects and mediate oxygen vacancies in host Bi2WO6 crystal lattice via varying content of Ti dopant to fabricate single-unit-cell layered structure, resulting in enhanced visible-light-driven photocatalytic efficiency. Density functional theory (DFT) calculations verified that the substitution of Bi cation in the crystal structure of Bi2WO6 can induce a new defect level, and increase the density of states (DOS) at the valence band maximum, which not only improve the charge dynamic but also the electronic conductivity. Remarkably, the single-unit-cell layers Ti-doped Bi2WO6 structure casts profoundly improved photocatalytic performance towards ceftriaxone sodium degradation, Cr(VI) reduction, and particularly higher photocatalytic H2 production rate, with a 5.8-fold increase compared to bulk Bi2WO6. Furthermore, the photoelectrochemical measurements unveil that the significantly higher charge migration and charge carrier dynamic counts for the elevated photocatalytic performance. After careful examination of experimental results, it was proved that the Ti doping mediated crystal defects, and engendered oxygen vacancies are critically important for controlling the photocatalytic performance of Bi2WO6.

A core–shell structure Cu–Ce–La/SSZ-13@ZSM-5 catalyst with a Cu–Ce–La/SSZ-13 core and a ZSM-5 shell was first synthesized by a self-assembly method and used for ammonia-selective catalytic reduction (NH3-SCR). In comparison with Cu–Ce–La/SSZ-13, Cu–Ce–La/SSZ-13@ZSM-5 with appropriate shell thickness presents better SCR activity and hydrothermal stability. We discovered an ion migration effect during the shell phase assembly process and further proposed that the ion migration effect was induced by the dissolution of the core phase during the growth of the shell. Part of the metal ions were migrated and redistributed during the assembly of the ZSM-5 shell, resulting in the transformation of [Cu(OH)]+–Z to Cu2+–2Z species and the functionalization of the shell phase. The functionalized shell is beneficial for the adsorption and activation of NH3. The results of an H2O resistance test and thermogravimetric analysis confirm that the coating of the hydrophobic shell can effectively improve the hydrothermal stability and H2O resistance of core–shell Cu–Ce–La/SSZ-13@ZSM-5.

Crystal defects are crucially important in semiconductor photocatalysis. To improve the reactivity of photocatalysts and attain desirable solar energy conversion, crystal defect engineering has gained considerable attention in real catalysts. Herein, we engineered crystal defects and mediate oxygen vacancies in host Bi

The reaction of dimorpholinomethane in fuming HNO3 was investigated. Interestingly, the major product was identified as N-nitrosomorpholine and a key intermediate N-hydroxymethylmorpholine was detected during the reaction by 1H-NMR tracking which indicates that the reaction proceeds via an unexpected nitrosolysis process. A plausible nitrosolysis mechanism for N-hydroxymethyldialkylamine in fuming nitric acid involving a HNO3 redox reaction is proposed, which is supported by both experimental results and density functional theory (DFT) calculations. The effects of ammonium nitrate and water on the nitrosolysis were studied using different ammonium salts as additives and varying water content, respectively. Observations show the key role of ammonium ions and a small amount of water in promoting the nitrosolysis reaction. Furthermore, DFT calculations reveal an essential point that ammonia, merged from the decomposition of the ammonium salts, acts as a Lewis base catalyst, and the hydroxymethyl group of the substrate participates in a hydrogen-bonding interaction with the NH3 and H2O molecules.

A carbazole-based hole-transporting material named 4,4′,4′′,4′′′-(9-octylcarbazole-1,3,6,8-tetrayl) tetrakis(N,N-bis(4-methoxyphenyl)aniline) (CZ-TA) has been developed through a one-step facile synthesis approach. The solution-processed planar perovskite solar cells (PVSCs) with 50 nm thick CZ-TA hole selective layer (HSL) contributes a power conversion efficiency of 18.32%, comparable to the most commonly used 200 nm spiro-OMeTAD (18.28%) HSLs. The improved hole extraction, transport and reduced recombination are found to endow CZ-TA-based devices with impressive fill factors over 81.0%. Importantly, the unit cost of HSL in PVSCs using CZ-TA can be as low as only 1/80 of that of spiro-OMeTAD, indicating that CZ-TA could be a promising candidate as HSLs for commercialization of the low-cost PVSC technology.

An absolute metal-free in-plane heterosystem consisting of g-C3N4 as scaffold and embedded half-metallic C(CN)3 as cocatalysts was conceptually designed for photoconversion of CO2. The no-slot joint between half-metallic C(CN)3 and g-C3N4 through covalent bonding generates a unique two-dimensional, π-conjugated hybrid structure, allowing obstacle-free transferring of the photogenerated electrons in g-C3N4 into C(CN)3 via an intrinsic driving force. Our theoretical calculations together with the in-situ Fourier transform infrared spectra indicate that the most negative charge distribution and binding energy with CO2 for C(CN)3 allow outstanding capture and chemical activation capacity toward CO2, and subsequently enable the optimized heterosystem to exhibit highly efficient and selective photocatalytic reduction of CO2 into CO, 7.8 and 1.9 times those produced with pristine and Pt-modified g-C3N4, respectively. The no-slot joint of organic half-metal cocatalysts with g-C3N4 may open up new opportunities for metal-free, polymer-based photocatalytic systems for CO2 conversion and solar fuel generation.

The reaction of dimorpholinomethane in fuming HNO

The ability to directly detect alkaline phosphatase (ALP) activity in undiluted serum samples is of great importance for clinical diagnosis. In this work, we report the use of the distinctive metal-to-ligand charge-transfer (MLCT) absorption properties of the Cu(BCA)2+ (BCA = bicinchoninic acid) reporter for the visual detection of ALP activity. In the presence of ALP, the substrate ascorbic acid 2-phosphate (AAP) can be enzymatically hydrolyzed to release ascorbic acid (AA), which in turn reduces Cu2+ to Cu+. Subsequently, the complexation of Cu+ with the BCA ligand generates the chromogenic Cu(BCA)2+ reporter, accompanied by a color change of colorless-to-purple of the solution with a sharp absorption band at 562 nm. The underlying MLCT-based mechanism has been demonstrated on the basis of density functional theory (DFT) calculations. Needless of any sequential multistep operations and elaborately designed colorimetric probe, the proposed MLCT-based method allows for a fast and sensitive visual detection of ALP activity within a broad linear range of 20 - 200 mU mL-1 (R2 = 0.999), with a detection limit of 1.25 mU mL-1. The results also indicate that it is highly selective and has great potential for the screening of ALP inhibitors in drug discovery. More importantly, it shows a good analytical performance for the direct detection of the endogenous ALP levels of undiluted human serum samples. Owing to the prominent simplicity and practicability, it is reasonable to conclude that the proposed MLCT-based method has a high application prospect in clinical diagnosis.

A new near-infrared fluorescent probe 1 based on the IR 780 skeleton was designed, synthesized and structurally characterized for the development of a chemosensor. UV-vis absorption and fluorescence spectroscopic studies show that probe 1 exhibits a high selectivity and sensitivity towards iridium(III) in an EtOH/H2O (1:4, v/v, pH 7.4, HEPES buffer, 1 mM) solution by forming a 1:1 complex with iridium(III). Experimental results further demonstrate that the probe 1–iridium(III) complex also has excellent application for the highly selective detection of glutathione.

A test method for the non-destructive determination of bolt length, anchoring length, and bolt body force is described. This addresses the problems of low accuracy, limited number of data, and untimely warning signs encountered with existing test methods. Numerical simulations of the bolt, resin, and rock system show that the length accuracy when using the velocity wave is lower than when using the acceleration wave. It is accepted practice to use the acceleration wave for length tests because of improved signal to noise ratios of the waveforms. Laboratory and in situ underground tests showed that the precision of the measurements meets field requirements. Using this method the anchor properties of each single bolt and, thus, the safety of the entire roadway support may be evaluated. Keywords: Stress wave, Non-destructive testing, Supporting effect, Stability evaluation

The separation of racemic molecules is of crucial significance not only for fundamental research but also for technical application. Enantiomers remain challenging to be separated owing to their identical physical and chemical properties in achiral environments. Chromatographic techniques employing chiral stationary phases (CSPs) have been developed as powerful tools for the chiral analysis and preparation of pure enantiomers, most of which are of biological and pharmaceutical interests. Here we report our efforts in developing high-performance phenylcarbamated cyclodextrin (CD) clicked CSPs. Insights on the impact of CD functionalities in structure design are provided. High-efficiency enantioseparation of a range of aryl alcohols and flavanoids with resolution values (Rs) over 10 were demonstrated by per(3-chloro-4-methyl)phenylcarbamated CD clicked CSP. Comparison study and molecular simulations suggest the improved enantioselectivity was attributed to higher interactions energy difference between the complexes of enantiomers and CSPs with phenylcarbamated CD bearing 3-chloro and 4-methyl functionalities.

A new fluorescent chemosensor based on a Rhodamine B and a benzyl 3-aminopropanoate conjugate (RBAP) was designed, synthesized, and structurally characterized. Its single crystal structure was obtained and analyzed by X-ray analysis. In a MeOH/H2O (2:3, v/v, pH 5.95) solution RBAP exhibits a high selectivity and excellent sensitivity for Sn2+ ions in the presence of many other metal cations. The binding analysis using the Job’s plot suggested the RBAP formed a 1:1 complex with Sn2+.

We have developed a method to improve the description of solute cavity defined by the interlocking-sphere model for continuum-solvent electrostatics calculations. Many models choose atomic radii from a finite set of atom types or uses an even smaller set developed by Bondi [J. Phys. Chem. 68, 441 (1964)]. The new model presented here allowed each atom to adapt its radius according to its chemical environment. This was achieved by first approximating the electron density of a molecule by a superposition of atom-centered spherical Gaussian functions. The parameters of the Gaussian functions were then determined by optimizing a function that minimized the difference between the properties from the model and those from ab initio quantum calculations. These properties included the electrostatics potential on molecular surface and the electron density within the core of each atom. The size of each atom was then determined by finding the radius at which the electron density associated with the atom fell to a prechosen value. This value was different for different chemical elements and was chosen such that the averaged radius for each chemical element in a training set of molecules matched its Bondi radius. Thus, our model utilized only a few adjustable parameters—the above density cutoff values for different chemical elements—but had the flexibility of allowing every atom to adapt its radius according to its chemical environment. This variable-radii model gave better solvation energy for 31 small neutral molecules than the Bondi radii did, especially for a quantum mechanics∕Poisson–Boltzmann approach we developed earlier. The improvement was most significant for molecules with large dipole moment. Future directions for further improvement are also discussed.