RSC Advances

Takise, Kent; Sato, Ayaka; Ogo, Shuhei; Seo, Jeong Gil; Imagawa, Ken-ichi; Kado, Shigeru; Sekine, Yasushi

doi: 10.1039/c9ra06042apmid: 35530488

The methylcyclohexane (MCH)–toluene cycle is a promising liquid organic hydride system as a hydrogen carrier. Generally, MCH dehydrogenation has been conducted over Pt-supported catalysts, for which it requires temperatures higher than 623 K because of its endothermic nature. For this study, an electric field was applied to Pt/TiO2 catalyst to promote MCH dehydrogenation at low temperatures. Selective dehydrogenation was achieved with the electric field application exceeding thermodynamic equilibrium, even at 423 K. With the electric field, “inverse” kinetic isotope effect (KIE) was observed by accelerated proton collision with MCH on the Pt/TiO2 catalyst. Moreover, Pt/TiO2 catalyst showed no methane by-production and less coke formation during MCH dehydrogenation. DRIFTS and XPS measurements revealed that electron donation from TiO2 to Pt weakened the interaction between catalyst surface and π-coordination of toluene. Results show that the electric field facilitated MCH dehydrogenation without methane and coke by-production over Pt/TiO2 catalyst.

Szynkiewicz, Natalia; Ordyszewska, Anna; Chojnacki, Jarosław; Grubba, Rafał

doi: 10.1039/c9ra06638apmid: 35530491

The monomeric diaminophosphinoboranes readily react with CO2 under mild conditions to cleanly form products of the general formula in the absence of a catalyst. The isolated products from the CO2-phosphinoboration were fully characterized by NMR spectroscopy, IR spectroscopy, and X-ray diffraction. The mechanism of CO2 phosphinoboration with diaminophosphinoboranes was elucidated by DFT calculations.

Aebly, Andrew H.; Levy, Jeffrey N.; Steger, Benjamin J.; Quirke, Jonathan C.; Belitsky, Jason M.

doi: 10.1039/c9ra90065apmid: 35532451

Correction for ‘Expedient synthesis of eumelanin-inspired 5,6-dihydroxyindole-2-carboxylate ethyl ester derivatives’ by Andrew H. Aebly et al., RSC Adv., 2018, 8, 28323–28328.

Sadasivan, Rajesh; Patel, Anjali

doi: 10.1039/c9ra04892hpmid: 35530462

A heterogeneous catalyst comprising mono-copper substituted phosphotungstate and hydrous zirconia was synthesized using wet impregnation method, characterized by various physico-chemical techniques and evaluated for solvent-free oxidation of styrene using TBHP as oxidant. Various reaction parameters like time, catalyst amount, amount of TBHP and temperature were optimized with focus on optimum selectivity of styrene-oxide. Further, the catalytic activity was compared with that of unfunctionalized PW11Cu to understand the role of the support. Finally, the role of each component of the reaction was clearly elucidated by a detailed kinetic study of the reaction using both the catalysts.

Huang, Cong; Chen, Leilei; Li, Haipu; Mu, Yanguang; Yang, Zhaoguang

doi: 10.1039/c9ra04445kpmid: 35530482

Bismuth tungstate (Bi2WO6) was successfully synthesized by a method combining ultrasonic solvothermal treatment and high-temperature calcination. The products were affirmed by X-ray diffraction, scanning electron microscopy, UV-vis diffuse reflection spectroscopy, X-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy. The characterization results indicated that calcination could improve the crystallinity and visible light utilization capacity of Bi2WO6. The photodegradation experiments showed that Bi2WO6 calcined at 450 °C for 3 h exhibited better photocatalytic activity for the degradation of norfloxacin and enrofloxacin under visible light irradiation than the catalyst prepared without calcination or calcined at other temperatures. Meanwhile, the effects of the amount of 450-Bi2WO6, the initial concentration of targets, and the pH of the solutions on the degradation were studied. Under the optimal conditions, the removal ratios reached to 92.95% (for norfloxacin) and 94.58% (for enrofloxacin) within 75 min. Furthermore, h+ and ·O2− were identified to affect the photodegradation process significantly, and the possible photocatalytic mechanism was proposed. The as-prepared sample was verified to possess good stability and reusability, suggesting its potential application prospect in the treatment of fluoroquinolone antibiotics.

Wiedemann, Dennis; Suard, Emmanuelle; Lerch, Martin

doi: 10.1039/c9ra05690dpmid: 35530459

After momentary attention as potential battery materials during the 1980s, sodium titanium disulphides, like the whole Na–Ti–S system, have only been investigated in a slapdash fashion. While they pop up in current reviews on the very subject time and again, little is known about their actual crystal-structural features and sodium-ion diffusion within them. Herein, we present a short summary of literature on the Na–Ti–S system, a new synthesis route to Na0.5TiS2-3R1, and results of high-temperature X-ray and neutron diffractometry on this polytype, which is stable for medium sodium content. Based thereon, we propose a revision of the crystal structure reported in earlier literature (missed inversion symmetry). Analyses of framework topology, probability-density functions, and maps of the scattering-length density reconstructed using maximum-entropy methods (all derived from neutron diffraction) reveal a honeycomb-like conduction pattern with linear pathways between adjacent sodium positions; one-particle potentials indicate associated activation barriers of ca. 0.1 eV or less. These findings are complemented by elemental analyses and comments on the high-temperature polytype Na0.9TiS2-2H. Our study helps to get a grip on structural complexity in the intercalates NaxTiS2, caused by the interplay of layer stacking and Na–Ti–vacancy ordering, and provides first experimental results on pathways and barriers of sodium-ion migration.

Trinh, Thi Kim Hoang; Schrodj, Gautier; Rigolet, Séverinne; Pinaud, Julien; Lacroix-Desmazes, Patrick; Pichavant, Loic; Héroguez, Valérie; Chemtob, Abraham

doi: 10.1039/c9ra05831apmid: 35530455

Although metathesis photoinduced catalysis is now well established, there is little development in thin film preparation using photochemically activated ring-opening metathesis polymerization (ROMP). Herein, a N-heterocyclic carbene (NHC) photogenerator (1,3-bis(mesityl)imidazolium tetraphenylborate) is combined with an inactive metathesis catalyst ([RuCl2(p-cymene)]2) to generate under UV irradiation an active catalyst (p-cymene)RuCl2 (NHC), that is capable of producing in a single step cross-linked copolymer films by ROMP of norbornene with dicyclopentadiene. The study shows that the photoinitiated catalytic system can be optimized by increasing the yield of photogenerated NHC through a sensitizer (2-isopropylthioxanthone), and by choosing [RuI2(p-cymene)]2 as precatalyst to provide a long-term photolatency. The cross-linked polymer structure is investigated by a range of techniques including gel content measurement, FT-IR and solid-state 13C NMR spectroscopy, TGA and DSC, which reveal a cross-linking mechanism proceeding through both metathesis and olefin coupling.

Hsueh, Ting-Jen; Lu, Chun-Liang

doi: 10.1039/c9ra03607epmid: 35530490

This study uses a solid YSZ electrolyte film in a SnO2 MEMS SO2 gas sensor of the semiconductor type to enhance the redox reaction. The YSZ film is prepared by RF sputtering. XRD analysis shows the presence of the (111), (200), (220) and (311) peaks that denote the crystallization planes of YSZ. The experimental results show that the SnO2 MEMS SO2 gas sensor with a YSZ film has a better sensor response than a pure SnO2 MEMS SO2 gas sensor or a YSZ MEMS SO2 gas sensor when the SO2 concentration and the sensor's temperature sensors are 250 ppb and 400 °C, respectively. The YSZ/SnO2 sensor's measured responses are around 6%, 45%, 20% and 16% when the sensor is respectively operated at 250 °C, 300 °C, 350 °C, and 400 °C.

Kang, Sunwoo; Moon, Jong Hun; Kim, Taekyung; Lee, Jin Yong

doi: 10.1039/c9ra04918epmid: 35530480

Charge transport and electronic transition properties of a series of newly designed anthracene-based non-doped blue emitters were investigated by density functional theory calculations. For a highly efficient non-doped device, Cz3PhAn-based emitters were designed to suppress the hole and electron reorganization energies required for structural relaxation with respect to the changes of charged states. As a result, the hole hopping rates of triphenylamine (TPA) and phenylbenzimidazole (PBI) substituted Cz3PhAn derivatives (1, 4, and 5–7) were tremendously enhanced as compared to that of Cz3PhAn due to the suppression of the reorganization energy of holes, λh. Moreover, 1 and 4 emitters showed almost identical hopping rates of holes and electrons, which can possibly lead to a perfect charge balance and high efficiency. The photo-physical properties showed that the emission energy of all 1–10 emitters is in 439–473 nm range. It is expected that our rational design strategy can help develop non-doped blue fluorescent emitters for high efficiency.

Wei, Chao; Xu, Denghui; Yang, Zaifa; Jia, Yetong; Li, Xiong; Sun, Jiayue

doi: 10.1039/c9ra04727apmid: 35530475

A series of Tm3+ and Dy3+ ions single- or co-doped Na3ScSi2O7 (NSSO) phosphors were prepared by a conventional solid state reaction method. The X-ray diffraction (XRD) patterns, photoluminescence (PL) properties, fluorescence decay curve and energy transfer behavior of the samples were studied. The XRD patterns show that all the diffraction peaks of the samples are consistent with the JCPDS standard data. Under UV excitation, the singly doped NSSO phosphors with Tm3+ and Dy3+ ions show blue and yellow characteristic emission. The emission color of NSSO:Tm3+,Dy3+ can be adjusted by the corresponding Tm3+–Dy3+ energy transfer. In addition, the chromaticity coordinate of NSSO:0.04Tm3+,0.13Dy3+ is (0.3195, 0.3214), which is close to the ideal white light (0.333, 0.33). These results show that NSSO:Tm3+,Dy3+ has potential application value in white light emitting diodes (WLEDs).