RSC Advances

Zhang, Huijie; Li, Kunlun; Zhang, Xiaojun; Dong, Chenghu; Ji, Haipeng; Ke, Runhui; Ban, Zhaojun; Hu, Yunfeng; Lin, Shaohua; Chen, Cunkun

doi: 10.1039/d0ra06448cpmid: 35517535

Strawberries are highly popular around the world because of their juicy flesh and unique taste. However, they are delicate and extremely susceptible to peroxidation of their membrane lipids during storage, which induces water loss and rotting of the fruit. This study investigated the effects of ozone treatment on the physiological traits, active oxygen metabolism, and the antioxidant properties of postharvest strawberry. The results revealed that the weight loss (WL) and respiration rate (RR) of strawberry were inhibited by ozone treatment (OT), while the decline of firmness (FIR) and total soluble solids (TSS) were delayed. Ozone also reduced the generation rate of superoxide radical anions , and the content of hydrogen peroxide (H2O2) enhanced the activity of superoxidase (SOD), catalase (CAT), ascorbate peroxidase (APX), and monodehydroascorbate reductase (MDHAR), as well as promoted the accumulation of ascorbic acid (ASA), glutathione (GSH), and ferric reducing/antioxidant power (FRAP). In addition, a total of 29 antioxidant-related proteins were changed between the OT group and control (CK) group as detected by label-free proteomics during the storage time, and the abundance associated with ASA–GSH cycle was higher in the OT group at the later stage of storage, and the qRT-PCR results were consistent with those of proteomics. The improvement of the antioxidant capacity of postharvest strawberry treated with ozone may be achieved by enhancing the activity of the antioxidant enzymes and increasing the expression of the antioxidant proteins related to the ascorbic acid–glutathione (ASA–GSH) cycle.

Zherikova, Kseniya V.; Verevkin, Sergey P.

doi: 10.1039/d0ra06880bpmid: 35517534

Volatile metal β-diketonates are well-known precursors used in Metal–Organic Chemical Vapour Deposition (MOCVD) for manufacturing film materials. Knowledge of vapour pressures and sublimation/vaporization thermodynamics of the MOCVD precursors is indispensable for optimization of deposition. However, the spread of available data could be unacceptably large for the same precursor for several reasons related to its chemical nature or incorrectly configured conditions of tensimetric investigation. In this work, we have developed an algorithm for a general diagnostic check, based on principles of group-additivity, for thermochemistry on solid–gas, liquid–gas, and solid–liquid phase transitions of metal–organic compounds and applied it to tris(beta-diketonato)iron complexes. The diagnostic tool helps to localize general “healthy” thermochemical interconnected data, and, subsequently, isolate molecules with definitely “ill” properties from the data pool. This diagnostic tool could be expanded and adapted for β-diketonate complexes with metals other than iron.

Shao, Wei; Chen, Yan-Ru; Xie, Feng; Zhang, Hao; Wang, Hai-Tao; Chang, Na

doi: 10.1039/d0ra06842jpmid: 35517549

It is of great importance to design and fabricate heterojunction photocatalysts to improve photocatalytic performance. In this work, a novel ZIF-67/AgCl/Ag heterojunction photocatalyst was successfully synthesized by a facile chemical etching, deposition–precipitation, light-induced reduction approach. After chemical etching by a AgNO3 precursor, the crystal size of ZIF-67 decreased remarkably together with the replacement of Co2+ in the framework of ZIF-67 by Ag+ via surface ion exchange. As a result, optical and electrochemical measurements indicated that the separation efficiency of light-induced electrons and holes obviously increased due to the formation of a ZIF-67/AgCl/Ag heterojunction and the surface plasmon resonance of Ag0. Meanwhile, the corresponding kinetic rate constant of ZIF-67/AgCl/Ag was estimated to be 0.1615 min−1, which was 17, 7.76 and 2.67 times as high as that of individual ZIF-67, AgCl and ZIF-67/AgCl, respectively. The ZIF-67/AgCl/Ag photocatalyst also exhibited good stability and reusability in the process of photodegradation. This work demonstrated a high efficiency photocatalyst for providing new sights into the preparation of a highly efficient MOF-based heterojunction photocatalyst and its potential applications in water purification.

Kotkondawar, Abhay Vijay; Rayalu, Sadhana

doi: 10.1039/c9ra10742hpmid: 35693040

The development of low-cost materials for the 100% dehydrogenation of metal hydrides is highly essential to vitalize the chemical hydride-based hydrogen economy. In this context, the ternary Co–Ce–Pt nanocomposite immobilized on functionalized catalytic support CGO is synthesized by the one step chemical reduction approach and has been directly employed for the ethanolysis of sodium borohydride. The co-operative effect of CGO and the synergy between metallic nanoparticles is investigated to determine the highest rate of hydrogen (H2) production. The maximum hydrogen generation rate (HGR) of 41.53 L (min gM)−1 is achieved with the Co0.97Pt0.03/CeOx/CGO nanohybrid from the alkaline ethanolysis of sodium borohydride (SB). In addition, the resultant nanohybrid exhibited a relatively low activation energy of 21.42 kJ mol−1 for the ethanolysis of SB. This enhanced catalytic activity may be attributed to the intermetallic charge transport among metallic Pt, Co/Co3O4, and CeOx counterparts. Moreover, the catalytic support CGO provides mesoporous functionalized surface and its intercalated GO layers promote charge transport. These results indicate that the resultant catalytic system described here for the dehydrogenation of SB can offer a portable and low-cost H2 supply for various fuel cell applications.

Iwamura, Shinichiroh; Motohashi, Shota; Mukai, Shin R.

doi: 10.1039/d0ra07590fpmid: 35517514

Titanium dioxide is a promising electrode material for lithium-ion capacitors. When using TiO2 as an electrode material, it is necessary to combine it with carbon at the nanometer level to improve its low electrical conductivity and low reactivity with Li+. However, preparation methods of reported TiO2/porous–carbon nanocomposites are generally not cost-effective, and their productivities are low. In this study, the vacuum liquid-pulse chemical vapor deposition (VLP-CVD) technique was developed to easily prepare TiO2/porous–carbon nanocomposites, where TiO2 nanoparticles with a diameter of ∼4 nm could be homogeneously deposited inside the pores of meso- or macroporous carbons. Because the deposited TiO2 nanoparticles had access to effective electrically conductive paths formed by the porous–carbon substrate, they showed a high discharge capacity of ∼200 mA h g−1-TiO2 (based on TiO2 weight). In particular, the composite prepared from macroporous carbon showed an extremely high rate performance, where 50% of the discharge capacity was retained at a current density of 15 000 mA g−1 when compared to that measured at 50 mA g−1. In addition, the composite also showed very high cyclability, where 80% of the discharge capacity was retained at the 10 000th cycle. Because the VLP-CVD technique can be performed using simple apparatus and commercially available starting materials, it can be expected to boost industrial production of TiO2/porous–carbon for lithium-ion capacitors.

Pandhi, Twinkle; Cornwell, Casey; Fujimoto, Kiyo; Barnes, Pete; Cox, Jasmine; Xiong, Hui; Davis, Paul H.; Subbaraman, Harish; Koehne, Jessica E.; Estrada, David

doi: 10.1039/d0ra04786dpmid: 35517530

Graphene has proven to be useful in biosensing applications. However, one of the main hurdles with printed graphene-based electrodes is achieving repeatable electrochemical performance from one printed electrode to another. We have developed a consistent fabrication process to control the sheet resistance of inkjet-printed graphene electrodes, thereby accomplishing repeatable electrochemical performance. Herein, we investigated the electrochemical properties of multilayered graphene (MLG) electrodes fully inkjet-printed (IJP) on flexible Kapton substrates. The electrodes were fabricated by inkjet printing three materials – (1) a conductive silver ink for electrical contact, (2) an insulating dielectric ink, and (3) MLG ink as the sensing material. The selected materials and fabrication methods provided great control over the ink rheology and material deposition, which enabled stable and repeatable electrochemical response: bending tests revealed the electrochemical behavior of these sensors remained consistent over 1000 bend cycles. Due to the abundance of structural defects (e.g., edge defects) present in the exfoliated graphene platelets, cyclic voltammetry (CV) of the graphene electrodes showed good electron transfer (k = 1.125 × 10−2 cm s−1) with a detection limit (0.01 mM) for the ferric/ferrocyanide redox couple, [Fe(CN)6]−3/−4, which is comparable or superior to modified graphene or graphene oxide-based sensors. Additionally, the potentiometric response of the electrodes displayed good sensitivity over the pH range of 4–10. Moreover, a fully IJP three-electrode device (MLG, platinum, and Ag/AgCl) also showed quasi-reversibility compared to a single IJP MLG electrode device. These findings demonstrate significant promise for scalable fabrication of a flexible, low cost, and fully-IJP wearable sensor system needed for space, military, and commercial biosensing applications.

Hu, Xue-fang; Lu, Chang-gui; Wang, Quan; Xu, Jing-kun; Cui, Yi-ping

doi: 10.1039/d0ra07228apmid: 35517553

Cesium lead-halide (CsPbX3; X = Cl, Br, I) perovskite microstructure arrays have become the basis for laser array applications, due to their outstanding spectral coherence, low threshold, and wideband tunability. Furthermore, the common fabrication methods for these arrays have the limitation to achieve both tailored design and high resolution simultaneously. Herein, we report a high-precision, template-assisted, wet etching (TAWE) method for the preparation of perovskite microstructure arrays. This method possesses the advantages of flexible design, controllable size, and ultrahigh accuracy (the resolution can reach 1 μm or higher). A 20 × 20 inverted pyramid array with a diameter of 3 μm and a period of 4 μm was fabricated using this method. CsPbBr3 perovskite quantum dots fabricated by means of hot injection were filled into the inverted pyramid array via spin-coating and pumped using a laser with a wavelength of 400 nm. The lasing characteristics of the array were then measured and analyzed; the threshold was measured to be 37.6 μJ cm−2, and the full width at half maximum of the amplified spontaneous emission spectrum was found to be about 4.7 nm. These results demonstrate that perovskite microstructure arrays prepared via this method have potential applications in laser arrays.

Yumigeta, Kentaro; Brayfield, Cassondra; Cai, Hui; Hajra, Debarati; Blei, Mark; Yang, Sijie; Shen, Yuxia; Tongay, S.

doi: 10.1039/d0ra07539fpmid: 35517551

We demonstrate the synthesis of layered anisotropic semiconductor GeSe and GeSe2 nanomaterials through low temperature (∼400 °C) and atmospheric pressure chemical vapor deposition using halide based precursors. Results show that GeI2 and H2Se precursors successfully react in the gas-phase and nucleate on a variety of target substrates including sapphire, Ge, GaAs, or HOPG. Layer-by-layer growth takes place after nucleation to form layered anisotropic materials. Detailed SEM, EDS, XRD, and Raman spectroscopy measurements together with systematic CVD studies reveal that the substrate temperature, selenium partial pressure, and the substrate type ultimately dictate the resulting stoichiometry and phase of these materials. Results from this work introduce the phase control of Ge and Se based nanomaterials (GeSe and GeSe2) using halide based CVD precursors at ATM pressures and low temperatures. Overall findings also extend our fundamental understanding of their growth by making the first attempt to correlate growth parameters to resulting competing phases of Ge–Se based materials.

Ishchenko, Olga M.; Lamblin, Guillaume; Guillot, Jérôme; Infante, Ingrid C.; Guennou, Maël; Adjeroud, Noureddine; Fechete, Ioana; Garin, Francois; Turek, Philippe; Lenoble, Damien

doi: 10.1039/d0ra06455fpmid: 35517541

Mesoporous TiO2 films with enhanced photocatalytic activity in both UV and visible wavelength ranges were developed through a non-conventional atomic layer deposition (ALD) process at room temperature. Deposition at such a low temperature promotes the accumulation of by-products in the amorphous TiO2 films, caused by the incomplete hydrolysis of the TiCl4 precursor. The additional thermal annealing induces the fast recrystallisation of amorphous films, as well as an in situ acidic treatment of TiO2. The interplay between the deposition parameters, such as purge time, the amount of structural defects introduced and the enhancement of the photocatalytic properties from different mesoporous films clearly shows that our easily upscalable non-conventional ALD process is of great industrial interest for environmental remediation and other photocatalytic applications, such as hydrogen production.

Tsuboi, Setsuko; Jin, Takashi

doi: 10.1039/d0ra06495epmid: 35517522

Indocyanine green (ICG) labelled recombinant annexin V proteins (ICG–EGFP–Annexin V and ICG–mPlum–Annexin V) were synthesized for dual-colour fluorescence imaging of tumour cell apoptosis in vitro and in vivo. The ICG-labelled fluorescent annexin V proteins showed dual (near-infrared and visible) fluorescence emissions with binding ability to phosphatidylserines on the plasma membranes of apoptotic cells. Although several types of fluorescence labelled annexin V (e.g. FITC–annexin V, Cy3- and Cy5-annexin V) have been reported, there are no dual-colour (near-infrared/visible) emitting apoptosis-detection probes which can be used in vitro and in vivo. In this paper, the utilities of the dual-colour fluorescent annexin V are demonstrated for in vitro and in vivo fluorescence imaging of the apoptosis of human breast tumour cells induced by an antibody–drug conjugate, Kadcyla. The results suggest that the present annexin V probes will be useful to visualize the action of anti-cancer drugs against tumours both at the cellular and whole-body level.