An electro-deoxidation approach to co-converting antimony oxide/graphene oxide to antimony/graphene composite for sodium-ion battery anode

Improving the Initial Coulombic Efficiency of Sodium-Storage Antimony Anodes via Electrochemically Alloying Bismuth

Improving cycling stability while maintaining a high initial Coulombic efficiency (ICE) of the antimony (Sb) anode is always a trade-off for the design of electrodes of sodium-ion batteries (SIBs). Herein, we prepare a carbon-free Sb8Bi1 anode with an ICE of 87.1% at 0.1 A g-1 by a one-step electrochemical reduction of Sb2O3 and Bi2O3 in alkaline solutions. The improved ICE of the Sb8Bi1 anode is due to the alloying of bismuth (Bi) that prevents irreversible interfacial reactions during the sodiation process. Unlike carbon buffers, the use of Bi will reduce the number of side reactions between the carbon buffer and sodium. Moreover, Bi2O3 can promote the reduction of Sb2O3 and reduce the particle size of Sb from ∼20 μm to below 300 nm. The electrolytic products can be modulated by controlling the cell voltages and electrolysis time. The electrolytic Sb8Bi1 anode delivered a capacity of 625 mAh g-1 after 200 cycles with an ICE of 87.1% at 0.1 A g-1 and even 625 mAh g-1 at 1 A g-1 over 100 cycles. Hence, alloying Bi into Sb is an effective way to make a long-lasting Sb anode while maintaining a high Coulombic efficiency.

Faceted Antimony Particles with Interiors Reinforced with Reduced Graphene Oxide as High-Performance Anode Material for Sodium-Ion Batteries

The attainment of "true reinforcement" in a composite and harnessing of the associated beneficial effects have been demonstrated here through the development of faceted crystalline Sb particles having the interiors reinforced with reduced graphene oxide (rGO). Such a unique and "near-ideal" micro/nanocomposite architecture has been achieved via a facile/cost-effective route by facilitating heterogeneous nucleation/growth of Sb-oxide particles on/around dispersed rGO sheets upon incorporation of the same directly into the precursor suspension, followed by the reduction of Sb-oxide to Sb, in intimate contact with the rGO, during the subsequent single heat-treatment step. As a potential anode material for Na-ion batteries, the as-developed Sb/rGO composite exhibits a reversible Na-storage capacity of ∼550 mAh/g (@ 0.2 A/g) and a fairly high first cycle Coulombic efficiency (CE) of ∼79%, with the good reversibility being attributed to the coarse particle size of Sb and encompassing of rGO sheets inside the Sb particles. Furthermore, despite the coarse particle size, the Sb/rGO-based electrode exhibits outstanding cyclic stability, with negligible capacity fade up to 150 cycles (viz., ∼97% capacity retention), and rate capability, with >86% capacity being obtained upon raising the current density from 0.1 to 2 A/g, resulting in a capacity of ∼490 mAh/g, even at 2 A/g.

Graphene-based materials for metronidazole degradation: A comprehensive review

Due to its cytotoxic effect, metronidazole (MNZ) is a drug commonly used to treat bacterial, protozoal, and microaerophilic bacterial infections. After consumption, it undergoes a series of metamorphic reactions that lead to the degradation of oxidized, acetylated, and hydrolyzed metabolites in the environment. To eliminate such pollutants, due to their high potential, adsorption and photocatalysis extensive processes are used in which graphene can be used to improve efficiency. This review analyses the use of graphene as an absorbent and catalyst with a focus on absorption and photocatalytic degradation of MNZ by graphene-based materials (GBMs). The parameters affecting the adsorption, and photocatalytic degradation of MNZ are investigated and discussed. Besides, the basic mechanisms occurring in these processes are summarized and analyzed. This work provides a theoretical framework that can direct future research in the field of MNZ removal from aqueous solutions.

Engineering Nanostructured Antimony-Based Anode Materials for Sodium Ion Batteries

Sodium-ion batteries (SIBs) are considered a potential alternative to lithium-ion batteries (LIBs) for energy storage due to their low cost and the large abundance of sodium resources. The search for new anode materials for SIBs has become a vital approach to satisfying the ever-growing demands for better performance with higher energy/power densities, improved safety and a longer cycle life. Recently, antimony (Sb) has been extensively researched as a promising candidate due to its high specific capacity through an alloying/dealloying process. In this review article, we will focus on different categories of the emerging Sb based anode materials with distinct sodium storage mechanisms including Sb, two-dimensional antimonene and antimony chalcogenide (Sb2S3 and Sb2Se3). For each part, we emphasize that the novel construction of an advanced nanostructured anode with unique structures could effectively improve sodium storage properties. We also highlight that sodium storage capability can be enhanced through designing advanced nanocomposite materials containing Sb based materials and other carbonaceous modification or metal supports. Moreover, the recent advances in operando/in-situ investigation of its sodium storage mechanism are also summarized. By providing such a systematic probe, we aim to stress the significance of novel nanostructures and advanced compositing that would contribute to enhanced sodium storage performance, thus making Sb based materials as promising anodes for next-generation high-performance SIBs.

Engineering of physical properties of spray-deposited nanocrystalline Sb2O3 thin films by phase transformation

Nanostructured Sb₂O₃ thin films have been deposited onto glass substrates by using the chemical spray pyrolysis technique, and the effect of precursor solution volume on the physical properties was investigated for the first time. The prepared films were characterized in detail by using x-ray diffraction, field-emission scanning electron microscopy with energy dispersive x-ray analysis (FESEM-EDAX), UV-vis absorption and transmission spectroscopy, Raman spectroscopy analysis and electrical resistivity measurement. X-ray diffraction analysis shows that the senarmontite cubic phase is completely transferred to the valentinite orthorhombic phase as the precursor solution volume is increased. This phase transformation as a function of precursor volume is discussed in detail. The FESEM-EDAX analysis reconfirms the phase change showing well-defined nano-dimensional cubic hexagonal and orthorhombic octahedral morphologies with excellent stoichiometry. The optical property studies show that the bandgap energy of Sb₂O₃ varies from 3.43-3.98 eV as a function of precursor quantity. The as-grown Sb₂O₃ thin films are semiconducting in nature. The measured values of electrical resistivity and activation energy are found to be dependent on the spray solution volume. The electrical resistivity of deposited Sb₂O₃ thin films shows variation from 26.15 × 10²-34.27 × 10² Ω cm and the activation energy of the films is in the order of 0.763-0.773 eV.

Application of graphene-based materials for removal of tetracyclines using adsorption and photocatalytic-degradation: A review

Tetracyclines are extensively used to treat human and animal infectious diseases due to its effective antimicrobial activities. About 70-90% of its parent materials are released into the environment through urine and feces, implying they are the most frequently detected antibiotics in the environment with high ecological risks. Adsorption and photocatalysis have been promising techniques for the removal of tetracyclines due to effectiveness and efficiency. Graphene-based materials provide promising platforms for adsorptive and photocatalytic removal of tetracyclines from aqueous environment owning to distinctive remarkable physicochemical, optical, and electrical characteristics. Herein, we intensively reviewed the available literatures in order to provide comprehensive insight about the applications and mechanisms of graphene-based materials for removal of tetracyclines via adsorption and phototocatalysis. The synthesis methods of graphene-based materials, the tetracycline adsorption and photocatalytic-degradation conditions, and removal mechanisms have been extensively discussed. Finally concluding remarks and future perspectives have been deduced and recommended to stimulate further researches in the subject. The review study can be used as theoretical guideline for further researchers to improve the current approaches of material synthesis and application towards tetracyclines removal.