RSC Advances

Liao, ChunFa; Fu, ZanHui; Que, LiangHua; Tang, Hao; Wang, Xu

doi: 10.1039/d3ra03003bpmid: 37575402

Neodymium is mainly obtained by electrolysis of a molten LiF-NdF3-Nd2O3 system. LiF-NdF3 is a basic system, and the phase diagram of this system provides important information in the production of electrolytic neodymium. An accurate LiF-NdF3 binary phase diagram helps in the selection of the appropriate molten salt component in production and optimizing the production process, which is of great significance to improve the electrolysis efficiency and reduce the production cost. To obtain an accurate phase diagram of the LiF-NdF3 binary system, liquidus and solidus temperatures were experimentally determined in the LiF-NdF3 binary system by differential scanning calorimetry. The experimental results were used to construct the phase diagram and develop a new database for the LiF-NdF3 system using the FactSage software. The sub-regular solution model was used to describe the excess Gibbs free energy of the liquid phase, and the thermodynamic optimization calculation was carried out for the binary system. The binary interaction coefficients 0L = −39 966 + 17.68 T, 1L = −7667 + 26.1 T, and 2L = −6000 were used to describe the system's excess Gibbs free energy. The results show that the eutectic point of the system is 68.4% LiF-31.6% NdF3 at 731.5 °C. The effects of industrial and high purity NdF3 and the presence of Nd2O3 on the liquidus temperature of the LiF-NdF3 system were also investigated, high liquidus temperatures have been observed in tests using industrial NdF3 and NdF3 feedstock that contains a specific quantity of Nd2O3.

Ye, Liandong; Liu, Min; Wang, Xiao; Yu, Zhihong; Huang, Zhihao; Zhou, Nianchen; Zhang, Zhengbiao; Zhu, Xiulin

doi: 10.1039/d3ra04205gpmid: 37575403

Sequences can have a dramatic impact on the unique properties and self-assembly in natural macromolecules, which has received increasing interest. Herein, we report a series of discrete amphiphilic co-oligomers with the same composition but different building blocks in a semirigid backbone. These sequence-defined oligomers possess two primary amine groups on the side chain of the azobenzene building block, and hence, they become amphipathic due to quaternization of the amine groups when protonated in acidic aqueous solution. These oligomer isomers assembled into different nanoparticles, including nanofibers, hollow vesicles and spherical micellar complexes, in a THF/water/HCl mixture under the same conditions. UV-vis absorption spectra, differential scanning calorimetry (DSC) and X-ray scattering (XRD) experiments combined with theoretical calculations reveal that the sequence-controlled co-oligomers induce different molecular packing conformations and arrangement modes of building blocks in self-assembly. Furthermore, these self-assembled nanoparticles demonstrate photoresponsive morphological transformation and fluorescence emission under UV light irradiation due to trans-to-cis photoisomerization of azobenzene. This work demonstrates that customizing functional nanoparticles can be achieved by controlling the sequence structure in synthetic co-oligomers.

Liang, Bo; Yang, Tingting; Yang, Huiqian; Zhao, Jinsheng; Dong, Yunyun

doi: 10.1039/d3ra01926hpmid: 37583673

The conventional Li-ion battery composite electrode material composed of CuO and carbon nanotubes (CNTs) suffer from poor contact between CuO and CNTs. This results in high electrode resistance and poor electrochemical performance. To solve this problem, CuO@humic acid (HA) @CNT anode material with cross-linked network structure was generated by linking CuO and CNT with HA as a coupling agent. For comparison, CuO@HA or CuO@CNT were also prepared in the absence of CNT or HA, respectively. The results showed that CuO@HA@CNT had lower charge transfer resistance, higher conductivity, lithium-ion diffusion coefficient, specific capacity, and rate capability than CuO@HA and CuO@CNT. The specific capacity of the CuO@HA@CNT electrode was significantly better than that of the composite electrode materials of CuO and CNT, which have been prepared by scientists using various methods. Due to the introduction of HA, not only was the uniformly distributed flower-like CuO obtained, but also the specific capacity and rate capability of the electrode material were substantially improved. This study thus provides a good strategy to optimize the capability of transition metal oxide lithium-ion anode materials.

Liang, Weiqian; Wei, Shuyin; Lan, Longxia; Chen, Jinfeng; Zhou, Yingyue; Zhao, Jiawei; Wang, Hao; Gao, Rui; Zeng, Feng

doi: 10.1039/d3ra04189apmid: 37583675

Heavy metal cations are a typical type of inorganic pollutant that has persistent distribution characteristics in aquatic environments and are easily adsorbed on carriers, posing serious threats to ecological safety and human health. Some studies have shown that the coexistence of dissolved organic matter (DOM) and microplastics (MPs) promotes the adsorption of heavy metal cations, but the mechanism of promoting the adsorption process has not been thoroughly studied. In this study, the effect of polystyrene microplastics (PSMPs) on the binding properties of Pb2+ onto humic acid (HA) in aquatic environments was investigated by spectral analysis and two-dimensional correlation (2D-COS) analysis. When PSMPs co-existed with HA, the adsorption capacity of Pb2+ increased. On the one hand, Pb2+ is directly adsorbed on HA through the mechanism of complexation reaction, ion exchange and electrostatic interaction. On the other hand, Pb2+ is first adsorbed on PSMPs by electrostatic action and indirectly adsorbed on HA in the form of PSMPs–Pb2+ owing to the interaction between HA and PSMPs, which increases the adsorption amount of Pb2+ on HA. This study is significant for studying the migration and regression of heavy metal cation contaminants when PSMPs co-exist with DOM in an aqueous environment.

Raguindin, Ricky Kristan M.; Mercado, Candy C.

doi: 10.1039/d3ra04092epmid: 37583667

Rapid and more environment-friendly means of gold nanoparticle synthesis is necessary in many applications, as in ion detection. Leaf extracts have become effective and economical reducing agents for gold nanoparticle formation, however, effects of extract combinations have not been thoroughly investigated. With the exploitation of combined extract effects, gold nanoparticles were synthesized then functionalized and investigated to produce selected nanoparticle systems which are capable of detecting aqueous lead(ii) ions with minimum detection limits of 10–11 ppm. The measured localized surface plasmon resonance absorption peaks of the gold nanoparticles were 541–800 nm for the synthesis and 549 nm for the functionalization. The diameters of different gold nanoparticle systems were 17–37 nm. These were mostly quasi-spherical in morphology with some rod-, triangular-, and hexagonal plate-like particles. The biosynthesis used polyphenols and acids present in the extracts in the reduction of gold ions into gold nanoparticles, and in the nanoparticle capping and stabilization. Functionalization replaced the capping compounds with alliin, S-allylcysteine, allicin, and ajoene. Gold nanoparticle stability in aqueous systems was verified for two weeks up to five months. The investigations concluded the practicability of the gold nanoparticles in lead(ii) ion detection with selectivity initially verified for other divalent cations.

Li, Yuqing; Zhang, Huimin; Li, Qian; Deng, Yuqin; Ye, Zi; Gui, Lin

doi: 10.1039/d3ra04497apmid: 37583671

This research work reports a novel method to achieve fast liquid metal (LM) injection in blind-end microchannels which is especially suitable for multi-layer microfluidic chips. This method is based on a texture-like surface bonding technology. The texture-like surface is fabricated on a polydimethylsiloxane (PDMS) slab with standard soft-lithography technology and bonded with another PDMS slab with microelectrode patterns on it. When injected with LM, the texture-like structure can prevent the LM from entering but allows the air inside to be released during the injection to achieve perfect blind-end complex LM electrodes. The experimental results show that it can achieve fast and perfect LM injection in the blind-end pattern and can also prevent the large area of the flat chamber from collapsing during bonding. We also parametrically studied the texture structure's size for bonding strength between the texture structure and the blank PDMS surface. In addition, we integrate three layers of blind-end complex liquid metal patterns into one multi-layer chip using this technology and later use this structure to realize series connection of two LM-based electroosmotic micropumps (EOP). Compared with the conventional LM-based EOP, the structure of the EOP chip was greatly simplified and resulted in a higher level of integration.

Wang, Jiawei; Wang, Guoqiao; Yu, Tian; Ding, Nengjie; Wang, Meicheng; Chen, Yao

doi: 10.1039/d3ra03789dpmid: 37583665

Biochar-modified TiO2 (C/TiO2) was prepared by a sol–gel method in this study to improve the photocatalytic capacity for ammonia–nitrogen (NH3–N) removal from aqueous solutions. The results showed that biochar was successfully modified on TiO2 and helped improve its photocatalytic performance for pollutant degradation. The removal capacity of ammonia–nitrogen on the synthesized photocatalyst performed well at pH 10 with 1 g L−1 C/TiO2 under both 60 (12.25 mg g−1) and 120 min (16.31 mg g−1) irradiation (xenon lamp, AM1.5, 25 A). Characterization of C/TiO2 through scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS), Brunauer–Emmett–Teller (BET), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Fourier-transform infrared spectrometry (FT-IR) analyses showed the successful introduction of biochar on TiO2. SEM-EDS and BET analyses displayed that C/TiO2 had a larger surface area and more pores than the raw materials. XRD spectroscopy illustrated that C/TiO2 had typical characteristic peaks of anatase-TiO2 and presented a good photocatalytic degradation performance. It was confirmed from XPS and FT-IR analyses that –COOH groups were present in C/TiO2 and originated from biochar modification, and these enhanced the photocatalytic performance. Through radical quenching experiments, it was found that superoxide radicals (˙O2−) played a dominant role in NH3–N photocatalytic reactions with hydroxyl radicals (˙OH) and valence band holes (h+) playing a synergistic role. N2 was the main degradation product after 6 h NH3–N photocatalytic degradation, which was much larger than NO3−/NO2− (both almost undetected) and NH3 (ca. 2 times lower than N2). The new composite C/TiO2 has potential for ammonia–nitrogen degradation in wastewater treatment and favorable for treating sewage sludge.

Tivari, Sunil R.; Kokate, Siddhant V.; Delgado-Alvarado, Enrique; Gayke, Manoj S.; Kotmale, Amol; Patel, Harun; Ahmad, Iqrar; Sobhia, Elizabeth M.; Kumar, Siva G.; Lara, Bianey García; Jain, Vicky D.; Jadeja, Yashwantsinh

doi: 10.1039/d3ra04100jpmid: 37583660

A new library of peptide-heterocycle hybrids consisting of an indole-3-carboxylic acid constituent conjugated with short dipeptide motifs was designed and synthesized by using the solid phase peptide synthesis methodology. All the synthesized compounds were characterized by spectroscopic techniques. Additionally, the synthesized compounds were subjected to in vitro antimicrobial activities. Two Gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa) and two Gram-positive (Streptococcus pyogenes and Staphylococcus aureus) were used for the evaluation of the antibacterial activity of the targeted dipeptide derivatives. Good antibacterial activity was observed for the screened analogues by comparing their activities with that of ciprofloxacin, the standard drug. Also, two fungi (Aspergillus niger and Candida albicans) were employed for the evaluation of the antifungal activity of the synthesized compounds. When compared to the standard drug Fluconazole, it was observed that the screened analogues exhibited good antifungal activity. In continuation, all the synthesized derivatives were subjected to integrated molecular docking studies and molecular dynamics simulations to investigate binding affinities, intermolecular interaction networks, and conformational flexibilities with deoxyribonucleic acid (DNA) gyrase and lanosterol-14-alpha demethylase. The molecular docking studies revealed that indole-3-carboxylic acid conjugates exhibited encouraging binding interaction networks and binding affinity with DNA gyrase and lanosterol-14 alpha demethylase to show antibacterial and antifungal activity, respectively. Such synthesis, biological activity, molecular dynamics simulations, and molecular docking studies of short peptides with an indole conjugate unlock the door for the near future advancement of novel medicines containing peptide-heterocycle hybrids with the ability to be effective as antimicrobial agents.

Mo, Baichuan; Chen, Chunxia; Peng, Jinsong

doi: 10.1039/d3ra04454hpmid: 37583662

Various multi-substituted pyrido[1,2-a]pyrimidin-4-ones were synthesized via a one-pot tandem CuI-catalyzed C–N bond formation/intramolecular amidation reaction at 130 °C in DMF. This protocol features simple operation, broad substrate scope, good functional group tolerance and gram scale preparation, thus allowing practical and modular synthesis of pyrido[1,2-a]pyrimidin-4-ones from readily available 2-halopyridine and (Z)-3-amino-3-arylacrylate ester in good to excellent yields.

Mohamed Ismail, Kamal Batcha; Arun Kumar, Manoharan; Jayavel, Ramasamy; Arivanandhan, Mukannan; Mohamed Ismail, Mohamed Abubakkar

doi: 10.1039/d3ra03892kpmid: 37583657

Supercapacitors are widely used energy storage systems in the modern world due to their excellent electrochemical performance, fast charging capability, easy handling, and high power density. In the present work, pure MoS2 and MoS2/Bi2S3 nanocomposites with different compositions of bismuth were synthesized by the hydrothermal method. The structural properties of the electrode materials were studied using the XRD technique, which confirmed the formation of MoS2 and the secondary phase of Bi2S3 while increasing Bi substitution. The morphological studies of the synthesized electrode materials were performed using SEM, TEM, and HRTEM techniques, which indicated the 3D layered hierarchical structure of MoS2 nanospheres and the nanosheet-like structure of Bi2S3. The electrochemical properties of pristine MoS2 and MoS2/Bi2S3 nanocomposites were analysed by CV, CP, and EIS techniques using a 2 M KOH electrolyte in a three-electrode system. The CV curves show evidence of significant improvement in the electrochemical performance of MoS2/Bi2S3 composites compared to that of pure MoS2. The calculated specific capacitances of MoS2/Bi2S3 nanocomposites were relatively higher than those of pristine MoS2. The 20 mol% Bi added sample showed a maximum specific capacitance of 371 F g−1, compared to pristine MoS2 and other samples at a current density of 1 A g−1. The kinetics of the electrochemical process was studied. The Nyquist plots indicated that the Bi-added nanocomposites had lower Resr and RCT values, which resulted in high electrochemical performance. The experimental results revealed that Bi-substitution can further enhance the electrochemical energy storage performance of MoS2 for supercapacitor applications.