RSC Advances

Liu, Jiayou; Nie, Qianqian; Tan, Zhongchao; Luo, Yulin; Wang, Shuai; Yu, Hesheng

doi: 10.1039/d0ra07559kpmid: 35519215

Bismuth tungstate (Bi2WO6) nanomaterials are widely used as visible-light driven photocatalysts. However, limited attention has been paid to the purity of prepared Bi2WO6 nanoparticles, which may affect the photocatalytic performance and hinder in-depth study of Bi2WO6. In this work, the impurities of Bi2WO6 formed during the hydrothermal process under a wide range of acid–base conditions (from 1.5 M HNO3 to 0.5 M NaOH) were qualitatively analyzed and accurately quantified for the first time. After confirmation of Bi2WO6 stability, the impurities were dissolved using acid or base treatment, followed by measurements of the ion concentrations using Inductively Coupled Plasma Mass Spectrometry (ICP-MS). Furthermore, various characterization techniques including XRD, FE-SEM, TEM, UV-Vis DRS, XPS and FTIR were implemented to explore the change in morphology and optical properties of Bi2WO6 prepared in different acid–base environments, and to facilitate qualitative analysis of impurities. The hydrolytic properties of raw materials used for the synthesis of Bi2WO6 were also analyzed with UV-Vis transmittance observation. Following these analyses, the types and contents of impurities in Bi2WO6 prepared by the hydrothermal method under different acid–base conditions were determined. Results show that the primary impurity is WO3·0.33H2O (41.09%) for the precursor prepared in 1.5 M nitric acid solution. When the pH of the precursor was in the range of 0.97–7.01, the synthesized Bi2WO6 has relatively high purity, and the impure products were identified as BiONO3. Bi2O3 began to appear when pH reached 9.01 and it reached 18.88% when pH was 12.98. The final product was Bi2O3 exclusively for the precursor conditioned in 0.5 M NaOH solution. In addition, the accuracy of the proposed quantitative method using ICP-MS was validated for several scenarios by weight difference experiments.

Shukla, Prashant; Saxena, Pooja; Bhardwaj, Nitin; Jain, V. K.

doi: 10.1039/d0ra07982kpmid: 35519233

Water in its various forms has been found to be one of the most abundant sources of energy on the planet after solar energy, and hydroelectric power plays a key role in renewable-energy supplies. Traditionally, harvesting tremendous amounts of hydrodynamic energy requires the deployment of complex, bulky, and expensive electromagnetic generators, which become inefficient at lower volumes of flowing or falling water, and then the energy is stored when there is an excess, but these techniques remain largely unperfected. Regardless of the diversity of development strategies, adopted methodologies, and working mechanisms, there are a wide range of energy scavengers, to effectively harness environmental friendly alternative energy sources. Robust, sustainable and technologically effective water energy harvesting devices, especially hydroelectric nanogenerators, are in the research spotlight globally, due to their numerous benefits to society, including cost effectiveness, clean and continuous electricity generation, and environmental applicability. Here the design and working mechanism involved in the development of a microporous polymer membrane assisted unique hydroelectric generator (MPA-HEG) based on triboelectrification and electrostatic induction phenomena is reported, which scavenges energy from continuously dripping water droplets sliding onto the surface of a hydrophobic microporous polymer membrane. MPA-HEG utilizes a very simple architecture that consists of a hydrophobic microporous polymer, poly(tetrafluoroethylene) (PTFE), membrane on a single-sided copper-clad laminate as a substrate and an aluminium electrode. Unlike other reported water energy harvesting devices with similar functionalities, the rational design of MPA-HEG does not necessitate any technologically complex structures to be embedded in the substrate. It has also been revealed that the interaction of water droplets on the smooth, water-resistant solid polymer surface in MPA-HEG switches ‘ON’ and connects the originally disconnected equivalent electrical components at the solid–liquid–solid interfaces, giving an uninterrupted electrical circuit, and transmuting the conservative interfacial effects into a bulk mechanism. Consequently, the instantaneous power output shows a vast increase over equivalent devices that are constrained either to triboelectric interfacial effects or moisture-induced electricity generation. This could serve the purpose of validating the inherent advantages of developing self-powered electronic devices, and this approach can also be effectively exploited for boosted power generation with realistic future applications.

Gao, Xintong; Zhang, Shuai; Liu, Jingchao; Xu, Shiqi; Li, Zenghe

doi: 10.1039/d0ra08116gpmid: 35519198

Semiconductor photocatalysis is widely proposed for decomposing multiple pollutants via photo-generated oxidative species. However, the photocatalytic degradation performance in practical settings still remains unsatisfactory due to the limited production of active oxidative species (AOS). In this work, a defect engineering strategy was developed to explore the superiority of oxygen vacancies (Vo) and their structural regulation to enhance AOS production for boosting photodegradation. Taking anatase TiO2 as a model photocatalyst, ultrathin TiO2 nanosheets containing abundant Vo and appropriate Fe doping exhibited an unprecedented 134 times higher activity in the degradation of Rhodamine B (RhB) (rate as high as 0.3073 min−1) than bulk anatase and were superior to most reported photocatalysts. The defect-rich ultrathin TiO2 nanosheets could be further applied in high-efficiency degradation of tetracycline hydrochloride (TC-HCl) with the degradation rate of 0.0423 min−1. The in situ electron paramagnetic resonance, advanced spectroscopic characterization and electrochemical measurement revealed the key role of Vo and Fe doping in facilitating the production of photo-generated holes and superoxide radicals (˙O2−) that were identified to be effective to decompose both RhB and TC-HCl. This research provides insight into defect engineering promoting AOS generation and gives inspiration for the design of efficient photocatalysts for photooxidation applications.

Yang, Yuexi; Ji, Zhoujieyu; Wu, Cheng; Ding, Yin-Yi; Gu, Zhenyu

doi: 10.1039/d0ra07911apmid: 35519201

This study focused on the effect of the heating process on the whole cotyledon soymilk and tofu. Whole cotyledon soymilk was made from soybean cotyledon and processed by enzymatic hydrolysis using cellulase and high-pressure homogeneity. In this study, a one-step heating method was selected for the cooking process of whole cotyledon soybean milk, and the whole cotyledon soybean milk was heated to 90 °C and held for 4 min. Results showed that the protein, total saccharides and dietary fiber content of the whole cotyledon soymilk were higher than those of the tradition soymilk due to the existence of bean dregs (okara). Both protein aggregation and protein–polysaccharide interaction were observed during the heating process. We also found a change in soymilk physicochemical characteristics such as particle size distribution, viscosity, surface hydrophobicity and soluble protein during the heating process. The results in this study showed that compared with traditional tofu, the phytic acid and trypsin inhibitor content in whole cotyledon tofu was lower, so its protein had higher digestibility in vitro. In conclusion, whole cotyledon tofu had better health properties and application prospects.

Sohrabi, Somayeh; Khedri, Mohammad; Maleki, Reza; Keshavarz Moraveji, Mostafa

doi: 10.1039/d0ra07500kpmid: 35519185

In this work, the effect of environment and additives on the self-assembly and delivery of doxorubicin (DOX) have been studied. A microfluidic system with better control over molecular interactions and high surface to volume ratio has superior performance in comparison to the bulk system. Moreover, carbon nanotube (CNT) and CNT-doped structures have a high surface area to incorporate the DOX molecules into a polymer and the presence of functional groups can influence the polymer–drug interactions. In this work, the interactions of DOX with both the polymeric complex and the nanotube structure have been investigated. For quantification of the interactions, H-bonding, gyration radius, root-mean-square deviation (RMSD), Gibbs free energy, radial distribution function (RDF), energy, and Solvent Accessible Surface Area (SASA) analyses have been performed. The most stable micelle–DOX interaction is attributed to the presence of BCN in the microfluidic system according to the gyration radius and RMSD. Meanwhile, for DOX-doped CNT interaction the phosphorus-doped CNT in the microfluidic system is more stable. The highest electrostatic interaction can be seen between polymeric micelles and DOX in the presence of BCN. For nanotube–drug interaction, phosphorus-doped carbon nanotubes in the microfluidic system have the largest electrostatic interaction with the DOX. RDF results show that in the microfluidic system, nanotube–DOX affinity is larger than that of nanotube–micelle.

Liu, Zhuang; Hou, Yi; Hu, Songqing; Li, Youming

doi: 10.1039/d0ra07808epmid: 35519228

In this study, several representative deep eutectic solvents (DESs) were designed to evaluate the solubility for alkali lignin (AL). It was found that DESs with lactic acid (LA) as hydrogen bond donors (HBDs) had good solubility for AL, in which lactic acid(LA) : choline chloride(ChCl) 10 : 1 showed excellent solubility with more than 17 wt% under a relatively mild condition of 60 °C. The results of gel permeation chromatography (GPC), FTIR and 1H and HSQC NMR spectroscopies revealed an important possible dissolution mechanism of AL in LA-ChCl, that is, AL could be depolymerized under the action of LA when dissolved in LA-ChCl. Then, a new connection would form between the phenolic groups on the lignin fragments and ChCl, which is similar to that between ChCl and LA in DES, leading to an increase in the molecule weight of lignin. The new connections could be easily broken under the action of heat (150 °C) or microwave to the redispersion of lignin fragments. The results would provide a theoretic base for the high-value application of lignin in bioresources.

Suzuki, Norihiro; Terashima, Chiaki; Nakata, Kazuya; Katsumata, Ken-ichi; Fujishima, Akira

doi: 10.1039/d0ra08019epmid: 35519229

A mesoporous titania thin film with a pseudo-single-crystal framework was synthesized on a lanthanum aluminate single-crystal substrate by a surfactant-assisted sol–gel method and liquid-phase epitaxial growth. The crystal lattices were well aligned within the titania framework. The highly energetic {001} facet was exposed on the top surface, which significantly enhanced the photocatalytic activity.

Nguyen, D. C.; Phung, Thanh Khoa; Vo, Dai-Viet N.; Le, Tu Hai; Khieu, Dinh Quang; Pham, Thong Le Minh

doi: 10.1039/d0ra06844fpmid: 35519212

Understanding the effect of Al doping on CO adsorption at ZnO(101̄0) is crucial for designing a high-performance CO gas sensor. In this work, we investigated the adsorption properties of CO on pristine and Al-doped ZnO(101̄0) by performing DFT+U calculations. It is found that the doping of Al on ZnO(101̄0) induces the semiconductor-to-metal transition and thus enhances the conductance of the substrate. Compared to the pristine ZnO(101̄0), the adsorption energy of CO on the Al-doped surfaces is significantly enhanced since Al doping has the effect of strengthening the adsorption bond. The bonding analysis reveals that CO adsorbs on pristine ZnO(101̄0) via the sole σ-dative donation between the CO HOMO 5σ and the empty states of the Zn cation while π-back donation from filled states of Zn or Al cations to the CO 2π* LUMO is facilitated on the Al-doped surfaces. The π-back donation also results in the red-shift of the CO stretching frequency on the Al-doped surfaces, contrasting to the blue-shift on the pristine surface. The simulated results demonstrate that the doping of Al to a three-fold coordinated site on ZnO(101̄0) is highly beneficial for boosting the performance of the CO gas sensor. Our theoretical investigation provides fundamental insights into the effect of Al doping on the sensing mechanism for CO at the ZnO(101̄0) surface.

Mech, Paulina; Makowski, Mariusz; Kawiak, Anna; Chylewska, Agnieszka

doi: 10.1039/d0ra06239apmid: 35519225

The design of drug structures that are non-toxic, easily transported and permeable to cellular barriers is currently one of the most growing research trends. Indeed, the structural similarity of 2-hydrazinopyrazine (2HP) to pyrazinamide, which has been successfully used in anti-tuberculosis therapy, makes 2HP a promising research object. Thus, herein, a complete analysis of the structure of 2HP and its physicochemical and cytotoxic properties was performed. Calf thymus DNA (CT-DNA) and bovine serum albumin (BSA) binding studies were conducted, which demonstrated the higher affinity of 2HP to BSA. Furthermore, cytotoxicity tests were performed, which proved that 2HP was non-toxic to human skin keratinocyte cells. Accordingly, 2HP was initially classified as a compound with potential application. Physicochemical investigations were performed using a wide range of experiments, which were supported by DFT calculations using the B3LYP functional and 6-311+G** basis set. The good correlation, high quality and correctness of the obtained parameters were proven although the data was obtained using independent techniques. Additionally, 42 tautomeric (prototrophic) forms of 2HP were found by searching the conformational hyperspace. The most energy stable 2HP conformer structure and the partial charge distribution were established. The preferred 2HP ionic forms preferred were presented, and models of the equilibrium occurring in aqueous solution were proposed. The hydrophilic character of 2HP was established based on the partition coefficient values determined by both experiment and theory. The PCM and SMD solvent models of water and n-octanol were used.

Khan, Tariq; Ali, Gul Shad

doi: 10.1039/d0ra90116dpmid: 35532489

Correction for ‘Variation in surface properties, metabolic capping, and antibacterial activity of biosynthesized silver nanoparticles: comparison of bio-fabrication potential in phytohormone-regulated cell cultures and naturally grown plants’ by Tariq Khan et al., RSC Adv., 2020, 10, 38831–38840, DOI: 10.1039/D0RA08419K.