Photocorrosion of Cuprous Oxide in Hydrogen Production: Rationalising Self‐Oxidation or Self‐Reduction

Cuprous Oxide (Cu₂O) is a photocatalyst with severe photocorrosion issues. Theoretically, it can undergo both self‐oxidation (to form copper oxide (CuO)) and self‐reduction (to form metallic copper (Cu)) upon illumination with the aid of photoexcited charges. There is, however, limited experimental understanding of the “dominant” photocorrosion pathway. Both photocorrosion modes can be regulated by tailoring the conditions of the photocatalytic reactions. Photooxidation of Cu₂O (in the form of a suspension system), accompanied by corroded morphology, is kinetically favourable and is the prevailing deactivation pathway. With knowledge of the dominant deactivation mode of Cu₂O, suppression of self‐photooxidation together with enhancement in its overall photocatalytic performance can be achieved after a careful selection of sacrificial hole (h⁺) scavenger. In this way, stable hydrogen (H₂) production can be attained without the need for deposition of secondary components.     

2D Transition Metal Dichalcogenides for Photocatalysis

Two-dimensional (2D) transition metal dichalcogenides (TMDs), a rising star in the post-graphene era, are fundamentally and technologically intriguing for photocatalysis. Their extraordinary electronic, optical, and chemical properties endow them as promising materials for effectively harvesting light and catalyzing the redox reaction in photocatalysis. Here, we present a tutorial-style review of the field of 2D TMDs for photocatalysis to educate researchers (especially the new-comers), which begins with a brief introduction of the fundamentals of 2D TMDs and photocatalysis along with the synthesis of this type of material, then look deeply into the merits of 2D TMDs as co-catalysts and active photocatalysts, followed by an overview of the challenges and corresponding strategies of 2D TMDs for photocatalysis, and finally look ahead this topic.     

Near-infrared broadband luminescence and energy transfer in Bi–Tm–Er co-doped lanthanum aluminosilicate glasses

The Bi–Tm–Er co-doped SiO₂–Al₂O₃–La₂O₃ (SAL) glasses, which exhibited a broadband near-infrared (NIR) emission, were investigated by the optical absorption and photoluminescence spectra. A super broadband NIR emission extending from 0.95 to 1.6 μm with a full-width at half-maximum (FWHM) of 430 nm which covered the whole O, E, S, C and L bands, was observed in Bi–Tm–Er co-doped samples under 808 nm excitation, as a result of the overlap of the Bi-related emission band (centered at 1270 nm) and the emission from Tm^{3+ 3}H₄→³F₄ transition (1450 nm) as well as Er^{3+ 4}I_13/2→⁴I_15/2 transition (1545 nm). In addition, a super broadband emission with amplitude relatively flat from 0.95 to 2.1 μm has been observed. The possible energy transfer between Bi-related centers, Tm³⁺ ions and Er³⁺ ions was proposed.     

Characteristics of Ba xSr 1–xTiO 3 thin films grown by pulsed laser ablation of rotating split targets of BaTiO 3 and SrTiO 3

We have grown heterostructures of Ba_xSr_1-xTiO₃(BST)/La_0.7Sr_0.3MnO₃(LSMO) on LaAlO₃(LAO) substrates by the pulsed laser deposition method. BST films with x=0.2,0.5,0.7 and 0.8 have been prepared using a novel rotating split-target arrangement. The lattice constant of the BST films is found to vary linearly with Ba/Sr ratio. An excellent cube-on-cube epitaxial relationship of (100)_BST||(100)_LSMO||(100)_LAO has also been obtained. Scanning electron microscopy studies have revealed smooth and crack-free BST films with a uniform grain size of about 100 nm. Dielectric measurements, made with patterned Au top electrodes and conducting LSMO bottom layers, have shown a maximum permittivity of approximately 280 at 5 kHz in BST films with x=0.7. P–E loop analyses of the Ba_0.7Sr_0.3TiO₃ and Ba_0.8Sr_0.2TiO₃ films have yielded remnant polarization values of 1.66 and 1.81C/cm², respectively. PACS 81.15Fg; 68.55Jk; 77.55+f     

Reduced graphene oxide as a solid-state electron mediator in Z-scheme photocatalytic water splitting under visible light

The effectiveness of reduced graphene oxide as a solid electron mediator for water splitting in the Z-scheme photocatalysis system is demonstrated. We show that a tailor-made, photoreduced graphene oxide can shuttle photogenerated electrons from an O(2)-evolving photocatalyst (BiVO(4)) to a H(2)-evolving photocatalyst (Ru/SrTiO(3):Rh), tripling the consumption of electron-hole pairs in the water splitting reaction under visible-light irradiation.     

Essential Oils from Vietnamese Asteraceae for Environmentally Friendly Control of Aedes Mosquitoes

Mosquitoes, in addition to being a biting nuisance, are vectors of several pathogenic viruses and parasites. As a continuation of our work identifying abundant and/or invasive plant species in Vietnam for use as ecologically friendly pesticidal agents, we obtained the essential oils of Blumea lacera, Blumea sinuata, Emilia sonchifolia, Parthenium hysterophorus, and Sphaeranthus africanus; analyzed the essential oils using gas chromatographic techniques; and screened the essential oils for mosquito larvicidal activity against Aedes aegypti and Aedes albopictus. The most active larvicidal essential oils were B. sinuata, which was rich in thymohydroquinone dimethyl ether (29.4%), (E)-β-caryophyllene (19.7%), α-pinene (8.8%), germacrene D (7.8%), and α-humulene (4.3%), (24-h LC₅₀ 23.4 and 29.1 μg/mL) on Ae. aegypti and Ae. albopictus, respectively, and Emilia sonchifolia, dominated by 1-undecene (41.9%) and germacrene D (11.0%), (24-h LC₅₀ 30.1 and 29.6 μg/mL) on the two mosquito species. The essential oils of P. hysterophorus and S. africanus were also active against mosquito larvae. Notably, B. sinuata, P. hysterophorus, and S. africanus essential oils were not toxic to the non-target water bug, Diplonychus rusticus. However, E. sonchifolia essential oil showed insecticidal activity (24-h LC₅₀ 48.1 μg/mL) on D. rusticus. Based on these results, B. sinuata, P. hysterophorus, and S. africanus essential oils appear promising for further investigations.     

Tubular bimetal oxysulfide CuMgOS catalyst for rapid reduction of heavy metals and organic dyes

Tubular bimetal oxysulfide CuMgOS catalyst was prepared using a feasible method at a low process temperature of 95°C. X‐ray diffractometry, X‐ray photoelectron spectrometry, field emission‐scanning electron microscopy, transmission electron microscopy, UV–Vis diffuse reflectance spectroscopy, photoluminescence emission spectrum, and nitrogen adsorption–desorption isotherms were used for CuMgOS characterizations. The CuMgOS reduction activities were investigated through the reduction of heavy metals of Cr (VI), Pb (II) and Hg (II) solutions, and the organic dyes of rhodamine‐B (RhB), methyl orange (MO) and methylene blue (MB) solutions under dark. The results showed that the CuMgOS prepared with an appropriate N₂H₄ amount for a suitable Cu (I)/Cu (II) ratio exhibited fast reduction activity without adding any reagents, with which the 100 mL Cr (VI), Pb (II) and Hg (II) solutions of 50 ppm were 100% reduced by 20 mg CuMgOS within 4 min, 6 min and 4 min, respectively. The 100 mL RhB, MO and MB solutions of 50 ppm were 100% reduced by 10 mg CuMgOS within 4 min, 5 min and 1 min, respectively, under the existence of NaBH₄. CuMgOS displayed excellent chemical stability for the re‐use tests on heavy metal ions and organic dyes. The excellent performance is attributed to CuMgOS bimetal oxysulfide catalyst with active surface reaction centers to interact with reactants, and the carrier hopping between Cu (I) and Cu (II).     

The magnetic phases of NdCu2

The magnetic phase diagram of a NdCu₂ single crystal is investigated by means of specific-heat measurements and neutron diffraction as a function of temperature and external magnetic field applied along the crystallographic b-direction. In the low temperature region we observe three commensurate phases AF1, F1, and F2. Their magnetic structures all consist of ferromagnetic (bc)-planes with different stacking sequences along the a-direction comprising 5, 3 and 8 chemical unit cells, respectively. Above 2.8 T the system is in a ferromagnetically aligned state (F3). Furthermore, there is an incommensurate phase AF3 between the low temperature commensurate phases and the paramagnetic state and, in a very narrow temperature region of only 0.2 K, an intermediate phase AF2 between AF1 and AF3. The Nd-moments are oriented along the b-direction in all phases.     

Infrared properties of the ambient pressure organic superconductor (BEDT-TTF)2I3

The infrared principal axes of superconducting β-(BEDT-TTF)₂I₃ are found to be directed along the chain axis and perpendicular to the axis in the a-b plane. At low temperatures well-defined plasma edges appear in both directions. Adopting a simplified 2-D orthorhombic band structure model, effective transfer integrals are found to be $\text{ = 0.10}\text{eV}\text{and}\text{t}{}_{\mathrm{perp;}}\text{= 0.13}\text{eV}$. A cross-over from semiconductor-like optical properties at 300 K to metallic-like optical properties at 40 K is observed in both directions. This is the first such observation in any organic conductor.