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The degradation of an AlGaN‐based deep‐ultraviolet laser diode during operation is studied. A rapid increase in threshold current without any facet mirror damage under direct current stress below the threshold current is observed, which is considered to limit the lifetime of continuous wave lasing to the level of seconds. The evolution of current–light and current–voltage characteristics suggests that the dominant mechanism of degradation is the increased loss of carriers before they can reach the active layer, i.e., the decrease in carrier injection efficiency. The decrease in emission intensity, which is more pronounced at lower current densities, and subsequent increase in sub‐threshold current indicate the increase in defect density under current stress, which is similar to the well‐analyzed degradation mechanism found in AlGaN‐based light‐emitting diodes. [ABSTRACT FROM AUTHOR]

Micro‐/nanomotors (MNMs) in water remediation have garnered significant attention over the past two decades. More recently, metal‐organic framework‐based micro‐/nanomotors (MOF‐MNMs) have been applied for environmental remediation; however, a comprehensive summary of research in this research area is yet to be reported. Herein, a review is presented to cover the recent advances in MOF‐MNMs and their various applications in wastewater remediation. The review presents a comprehensive introduction to MNMs, including different propulsion approaches, fabrication, and functionalization strategies, in addition to the unique features of MOF‐MNMs. The conception and various synthetic routes of MOF‐MNMs are extensively covered and the implementation of MOF‐MNMs in water‐related applications, including adsorption, degradation, sensing, and disinfection of different pollutants, is in depth discussed. Meanwhile, the propulsion and mechanism of action behind each MOF‐MNM are systematically studied. Finally, the review provides insights into the challenges and perspectives to build more effective MOF‐MNMs to cover versatile applications for wastewater treatment. [ABSTRACT FROM AUTHOR]

Halide perovskites are promising as the light absorbers of solar cells with efficient solar power conversion. However, why the degradation of perovskite solar cells (PSCs), especially at high temperatures, happens has not been completely understood to date. Herein, it is shown that evaporation of 4‐tert‐butylpyridine (4‐tBP) from the hole transport layer (HTL) of 2,2',7,7'‐tetrakis(N,N‐di‐p‐methoxyphenylamino)‐9,9'‐spirobifluorene (spiro‐OMeTAD) is one of possible degradation mechanisms in PSCs at a high temperature of 85 °C. In fresh PSCs, the chemical doping of the spiro‐OMeTAD HTL with lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) is not so efficient because of the formation of a LiTFSI:4‐tBP complex in the HTL. When PSCs are placed at 85 °C, 4‐tBP gradually evaporates from the HTL, resulting in the dissociation of the LiTFSI:4‐tBP complex. This 4‐tBP evaporation enhances the chemical doping of spiro‐OMeTAD by LiTFSI and makes the hole transport level of the spiro‐OMeTAD HTL deeper, thereby impeding hole extraction at the perovskite/spiro‐OMeTAD/Au interfaces. Herein, the 4‐tBP evaporation by covering PSCs with a fluoro‐polymer CYTOP layer, significantly improving the high‐temperature durability of PSCs, is suppressed. The basic understanding obtained in this study would help promote the spread of more thermally durable PSC products in the future. [ABSTRACT FROM AUTHOR]

Poly(methyl methacrylate) (PMMA) is a well‐known and widely used commodity plastic. High production amount of PMMA causes excessive waste creation that highlights the necessity of recycling. Conventional recycling methods require elevated temperatures to induce degradation or depolymerization. In this work, visible light induced photodegradation system by using dimanganese decacarbonyl (Mn2(CO)10) with high halogen affinity is reported. Halide functional photodegradable polymers are prepared by copolymerization of methyl methacrylate and methyl α‐chloroacrylate by conventional reversible addition‐fragmentation chain‐transfer polymerization. Synthesized copolymers are efficiently degraded to low molecular weight oligomers under visible light irradiation in the presence of Mn2(CO)10. Characteristics of precursors, degraded polymers, and kinetics of depolymerization are investigated by gel permeation chromatography (GPC), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), Fourrier transform infrared (FTIR), and proton nuclear magnetic resonance (1H‐NMR) spectroscopies. The reported approach is expected to trigger further development of more environmentally friendly recycling techniques in the near future as we are moving toward a greener and more sustainable world. [ABSTRACT FROM AUTHOR]

Sequence‐defined and degradable polymers can mimic biopolymers, such as peptides and DNA, to undertake life‐supporting functions in a chemical way. The design and development of well‐structured oligomers/polymers is the most concern for the public, even to further uncover their degradation process illustrating the degraded products and their properties. However, seldom investigation has been reported on the aforementioned aspects. In this work, the alternating photo‐reversible addition‐fragmentation chain‐transfer (photo‐RAFT) single unit monomer insertion (SUMI) of different N‐substituted maleimides and thermal radical ring‐opening SUMI of a cyclic ketene acetal monomer (i.e., 5,6‐benzo‐2‐methylene‐1,3‐dioxepane (BMDO)) is adopted, to produce two degradable pentamers owing to the conversion of the exo‐methylene group of BMDO into ester bonds along the main chains of the prepared products. Moreover, the possible degraded approach of pentamers is studied by combining high‐resolution mass spectrometry (HRMS) and liquid chromatography‐mass spectrometry (LC‐MS) for the first time. This work also sheds light on the precise structures and cytotoxicity of SUMI products and their degraded compounds, proposing a detailed and credible outlook for biomedical applications. [ABSTRACT FROM AUTHOR]

BACKGROUND: Vanadium‐doped manganese dioxide (V‐MnO2) was fabricated for effective photocatalytic degradation of ciprofloxacin (CIP) and moxifloxacin (MOXI) antibiotics under visible light. V‐MnO2 fabricated by simple redox method was characterized by spectrophotometry, scanning electron microscopy, energy‐dispersive X‐ray spectroscopy, X‐ray diffraction, zeta potential, dynamic light scattering (DLS), Fourier transform infrared spectroscopy and photoluminescence (PL) techniques. RESULTS: DLS measured average particles size of 93.18 nm for MnO2, which reduced to 88 nm for V‐ MnO2 and zeta potential indicated −11.5 mV for MnO2 and 17.7 mV for 1% V‐MnO2. PL spectra of V‐MnO2 was suppressed as compared to MnO2 spectra, indicating a decrease in electron hole recombination and leading to increased photocatalytic activity of V‐MnO2. Band gap results revealed a successful decrease in band gap of MnO2 from 3.30 to 2.82 eV after doping with 1% V. Maximum degradation of CIP and MOXI achieved was 92% ± 2.98% and 79.5% ±2.15%, respectively, at pH 6. Optimum visible light irradiation of 180 and 300 min was calculated for CIP and MOXI, respectively. V‐MnO2 catalyst was recyclable for three cycles. CONCLUSION: V‐MnO2 catalyst was successfully applied to treatment of CIP and MOXI in spiked real water supply and sewage wastewater samples. Computational molecular models of CIP, MOXI, MnO2 and V‐MnO2 were built and optimized. Total energy values measured by a semi‐empirical method revealed that V‐MnO2 structure was less stable than MnO2, with weakened bonds between Mn atoms of MnO2 structure after doping of V ions. © 2022 Society of Chemical Industry (SCI). [ABSTRACT FROM AUTHOR]

As one of the most outstanding allotropes of carbon assembled with a cylindrical nanostructure, carbon nanotubes (CNTs) have attracted extensive attention in the areas of material science and engineering due to their unique structural characteristics and physicochemical properties. Very recently, versatile hierarchical CNT‐based photocatalysts are of considerable interest in current research and applications ranging from fuel generation to environmental purification. Therefore, it is necessary to summarize the CNT‐based photocatalysts to provide essential references for the continuous research study. In this review, the different design strategies and flexible functionalizations for prototype construction are described and their typical research, especially the structure‐related or electronic‐effected mechanism in the photocatalytic reaction of pollutants degradation, water splitting, and CO2 reduction overviewed. Finally, the various aspects of CNT‐based photocatalysts are discussed for future developments in commercial applications. [ABSTRACT FROM AUTHOR]

Here, two B‐doped Cz‐grown Si materials with different Al concentrations are investigated concerning the long‐term behavior of excess charge carrier lifetime under injection at elevated temperature. By determining the defect density and the surface saturation current density, a delay in regeneration and a delay in the onset of surface‐related degradation is found in the material containing an order of magnitude more Al. Investigations under constant excess carrier concentration reveal that the effect of the delay is still significant, but less pronounced compared with constant generation conditions, so the effect causing the delay seems to be injection dependent. The findings can be explained by the higher activation energy for the splitting of Al−H pairs compared with splitting of B−H pairs, which might cause a delayed release in H from the dopant H configuration. Assuming that regeneration depends on this released H, the delay in regeneration can be explained by this model. [ABSTRACT FROM AUTHOR]

A highly accurate, simple and sensitive spectrofluorimetric analytical method for dapagliflozin (DGF) quantitation was developed. The proposed method was successively applied to DGF analysis in both its pure and pharmaceutical dosage forms. This method was developed to investigate DGF stability in its degradation products, as laid out in International Council for Harmonisation (ICH) rules. Kinetics of alkaline degradation of DGF was also calculated. The half‐life time (t1/2) of the reaction was 75.32 min. An alkaline degradation pathway was described. The present study involved measurement of the second‐derivative synchronous fluorescence intensity of DGF at Δλ = 30 nm. Peak amplitude was measured at 322 nm. Linear range of the calibration curve was 0.1–1.0 μg ml−1. Lower detection and quantitation limits were 0.023 and 0.071 μg ml−1, respectively, and indicated good sensitivity of the proposed method. Mean per cent recovery was 99.78 ± 1.78%. The proposed analytical approach was successfully applied to DGF in the quality control laboratory and would be suitable as a stability‐indicating assay. [ABSTRACT FROM AUTHOR]