Search

Methyl mercaptan (MM) is one kind of volatile sulfur compound (VSC) with odor and properties (inflammable, highly toxic, and corrosive) similar to H2S; therefore, the highly sensitive and selective monitoring of ambient MM by chemiresistors is strongly essential, but it remains a challenge owing to its relatively weak reducibility/response in comparison with H2S. In this study, a novel chemiresistor composed of hexahedral particles SBO-loaded CdS nanoparticles has been prepared via a facile chemical precipitation method for the super-sensitive and highly-selective recognition of MM. The heterostructural CdS/SBO (0.05%) chemiresistor exhibited an extremely high response (114.7) to 100 ppm MM at a relatively low operating temperature (100 °C) and was about 36- and 9-fold higher than pure SBO and CdS chemiresistor, respectively. Various characterizations suggested that the sulfurization–desulfurization reaction, the abundant oxygen vacancies, and the generation of n–n heterojunctions at the interface promote the redox reaction of surface-active substances, thereby, boosting the outstanding MM response characteristics. In addition, the heterostructural chemiresistor possesses good selectivity, weak humidity interference, a lower limit of detection (LoD) of 82 ppb, and long-term stability (∼6% decline of response after 120 days), which promises practical applications in air quality (odor) monitoring. [ABSTRACT FROM AUTHOR]

2D Ti3C2Tx MXene, possessing facile preparation, high electrical conductivity, flexibility, and solution processability, shows good application potential for enhancing device performance of perovskite solar cells (PVSCs). In this study, tetrabutylammonium bromide functionalized Ti3C2Tx (TBAB‐Ti3C2Tx) is developed as cathode buffer layer (CBL) to regulate the PCBM/Ag cathode interfacial property for the first time. By virtue of the charge transfer from TBAB to Ti3C2Tx demonstrated by electron paramagnetic resonance and density functional theory, the TBAB‐Ti3C2Tx CBL with high electrical conductivity exhibits significantly reduced work function of 3.9 eV, which enables optimization of energy level alignment and enhancement of charge extraction. Moreover, the TBAB‐Ti3C2Tx CBL can effectively inhibit the migration of iodine ions from perovskite layer to Ag cathode, which synergistically suppresses defect states and reduce charge recombination. Consequently, utilizing MAPbI3 perovskite without post‐treatment, the TBAB‐Ti3C2Tx based device exhibits a dramatically improved power conversion efficiency of 21.65% with significantly improved operational stability, which is one of the best efficiencies reported for the devices based on MAPbI3/PCBM with different CBLs. These results indicate that TBAB‐Ti3C2Tx shall be a promising CBL for high‐performance inverted PVSCs and inspire the further applications of quaternary ammonium functionalized MXenes in PVSCs. [ABSTRACT FROM AUTHOR]

The structural, electronic, optical, mechanical, lattice dynamics, and electronic transport properties of SrCu2O2 crystals were studied using first-principles calculations. The calculated band gap of SrCu2O2 using the HSE hybrid functional is about 3.33 eV, which is well consistent with the experimental value. The calculated optical parameters show a relatively strong response to the visible light region for SrCu2O2. The calculated elastic constants and phonon dispersion indicate that SrCu2O2 has strong stability in mechanical and lattice dynamics. The deep analysis of calculated mobilities of electrons and holes with their effective masses proves the high separation and low recombination efficiency of photoinduced carriers in SrCu2O2. [ABSTRACT FROM AUTHOR]

Antioxidants are molecules that can prevent the harmful effects of oxygen, help capture and neutralize free radicals, and thus eliminate the damage of free radicals to the human body. Persimmon tannin (PT) has excellent antioxidant activity, which is closely related to its molecular structure. We report here a comparative study of four characteristic structural units from PT (epicatechin gallate (ECG), epigallocatechin gallate (EGCG), A−type linked ECG dimer (A−ECG dimer), A−type linked EGCG dimer (A−EGCG dimer)) to explore the structure–activity relationship by using the density functional theory. Based on the antioxidation mechanism of hydrogen atom transfer, the most favorable active site for each molecule exerts antioxidant activity is determined. The structural parameters, molecular electrostatic potential, and frontier molecular orbital indicate that the key active sites are located on the phenolic hydroxyl group of the B ring for ECG and EGCG monomers, and the key active sites of the two dimers are located on the phenolic hydroxyl groups of the A and D' rings. The natural bond orbital and bond dissociation energy of the phenolic hydroxyl hydrogen atom show that the C11−OH in the ECG monomer and the C12−OH in the EGCG monomer are the most preferential sites, respectively. The most active site of the two A−linked dimers is likely located on the D' ring C20′ phenolic hydroxyl group. Based on computational analysis of quantum chemical parameters, the A−ECG dimer is a more potent antioxidant than the A−EGCG dimer, ECG, and EGCG. This computational analysis provides the structure–activity relationship of the four characteristic units which will contribute to the development of the application of PT antioxidants in the future. [ABSTRACT FROM AUTHOR]

A highly efficient MgBi2O6 (MBO)/TiO2 heterostructured photocatalyst for the evolution of H2 was successfully prepared using a one-step hydrothermal method. The phase structure, microstructure and optical properties of the MBO/TiO2 composites were investigated by various experimental techniques. A series of H2 production experiments were performed under visible light. The measured results indicated that the nanostructured MBO/TiO2 composite, with a stoichiometric molar ratio of MBO:TiO2 = 0.2%, displayed the best H2 production rate of 3413 μmol h−1 g−1. The excellent photocatalytic performance of the obtained composite material was due to the heterojunction formed between MBO and TiO2, which reduced the charge transfer resistance and accelerated the separation efficiency of the photogenerated electron–hole pairs. The reaction mechanism was also discussed in detail. [ABSTRACT FROM AUTHOR]

To improve the ferroelectric photovoltaic characteristic of bismuth sodium titanate-based lead-free ceramics. The B-site Mo-doped Na0.5, Bi0.5 (Ti1-x Mox) O3 (BNT-Mox, the value of x is 0 to 0.02) lead-free ferroelectric ceramic was synthesized by the conventional solid state reaction method. The optical band gap of the ceramic was researched by XRD, Raman spectroscopy, absorption spectroscopy, combining the calculations based on first-principles density functional theory (DFT). The experiment results show that with the increase of the content, the optical band gap decreases firstly and then increases. The minimum value of band gap is 2.33 eV when x = 1% and the maximum value of light absorption intensity is 69%. The DFT calculation results of the band structure and density of states show that the band gap is shifted from indirect to direct mode by the Mo 4d orbit after the Mo doped, and led to the decrease of band gap. There is a competitive relationship between the impurity energy level caused by Mo doping and the Moss-Bolstein effect in band gap regulation, which could control the band structure of BNT effectively. [ABSTRACT FROM AUTHOR]