Engineering Bi2O3-Bi2S3 heterostructure for superior lithium storage

Boosting electrocatalytic ammonia synthesis from nitrate by asymmetric chemical potential activated interfacial electric fields

The electrocatalytic nitrate reduction reaction (NO3- RR) has immense potential to alleviate the problem of groundwater pollution and may also become a key route for the environmentally benign production of ammonia (NH3) products. Here, the unique effects of interfacial electric fields arising from asymmetric chemical potentials and local defects were integrated into the binary Bi2S3-Bi2O3 sublattices for enhancing electrocatalytic nitrate reduction reactions. The obtained binary system showed a superior Faraday efficiency (FE) for ammonia production of 94 % and an NH3 yield rate of 89.83 mg gcat-1h-1 at -0.4 V vs. RHE. Systematic experimental and computational results confirmed that the concerted interplay between interfacial electric fields and local defects not only promoted the accumulation and adsorption of NO3-, but also contributed to the destabilization of *NO and the subsequent deoxygenation hydrogenation reaction. This work will stimulate future designs of heterostructured catalysts for efficient electrocatalytic nitrate reduction reactions.

Electrochemical coupling in subnanometer pores/channels for rechargeable batteries

Subnanometer pores/channels (SNPCs) play crucial roles in regulating electrochemical redox reactions for rechargeable batteries. The delicately designed and tailored porous structure of SNPCs not only provides ample space for ion storage but also facilitates efficient ion diffusion within the electrodes in batteries, which can greatly improve the electrochemical performance. However, due to current technological limitations, it is challenging to synthesize and control the quality, storage, and transport of nanopores at the subnanometer scale, as well as to understand the relationship between SNPCs and performances. In this review, we systematically classify and summarize materials with SNPCs from a structural perspective, dividing them into one-dimensional (1D) SNPCs, two-dimensional (2D) SNPCs, and three-dimensional (3D) SNPCs. We also unveil the unique physicochemical properties of SNPCs and analyse electrochemical couplings in SNPCs for rechargeable batteries, including cathodes, anodes, electrolytes, and functional materials. Finally, we discuss the challenges that SNPCs may face in electrochemical reactions in batteries and propose future research directions.

Visible light-driven photocatalytic thiol-ene/yne reactions using anisotropic 1D Bi2S3 nanorods: a green synthetic approach

Thiol-ene/yne click reactions play a significant role in creating carbon-sulfur (C-S) bonds, and there has been a growing interest in using visible-light photoredox catalysis for their formation. In this study, anisotropic 1D Bi2S3 nanorods were prepared using a simple polyol-assisted reflux method, and they were used as catalysts for the thiol-ene/yne click reactions under visible light irradiation. The developed protocol is highly compatible and tolerant to various substrates with excellent product yields. Also, thiol-ene and -yne reactions achieved maximum TONs of 93 and 95, respectively. Detailed mechanistic studies were conducted and supported by NMR studies, radical trapping utilizing TEMPO, and ESI-MS product analysis. The ability of Bi2S3 nanorods to catalyze thiol-ene/yne reactions is primarily due to the creation of photoexcited holes, which aid in the formation of thiyl radicals. This method can be scaled up to the gram-scale synthesis of benzyl styryl sulfide with an excellent chemical yield of 90%. The 1D Bi2S3 nanorods also demonstrated structural and morphological stability throughout five reaction cycles while maintaining a favorable photocatalytic activity. The developed methodology had the advantages of broad substrate scope, mild reaction conditions, scaled-up synthesis, and nonrequirement of free radical initiators.

PANI coupled hierarchical Bi2S3nanoflowers based hybrid nanocomposite for enhanced thermoelectric performance

Bismuth sulfide (Bi₂S₃) is a promising material for thermoelectric applications owing to its non-toxicity and high abundance of bismuth (Bi) and sulfur (S) elements on earth. However, its low electrical conductivity drastically reduces the value of the figure of merit (ZT). In this work, we have synthesized three-dimensional (3D) hierarchical Bi₂S₃nanoflowers (NFs) by the hydrothermal route and further incorporated them with conducting polymer polyaniline (PANI) by simple chemisorption method. We have investigated the thermoelectric properties of the as-prepared Bi₂S₃NFs and PANI/Bi₂S₃nanocomposite samples and it is demonstrated that the incorporation of the PANI matrix with the 3D hierarchical Bi₂S₃NFs provides a conducting substrate for the easy transport of the electrons and reduces the barrier height at the interface, resulting in ∼62% increment in the electrical conductivity as compared to Bi₂S₃NFs. Moreover, a decrement in the thermal conductivity of the PANI/Bi₂S₃nanocomposite is observed as compared to pristine Bi₂S₃NFs due to the increased phonon scattering at the interfaces facilitated by the hierarchical morphology of the NFs. Furthermore, an increment in the electrical conductivity and simultaneous decrement in the thermal conductivity results in an overall ∼20% increment in the figure of merit (ZT) for PANI/Bi₂S₃nanocomposite as compared to pristine Bi₂S₃NFs. The work highlights an effective strategy of coupling 3D hierarchical metal chalcogenide with conducting polymer for optimizing their thermoelectric properties.

Enhanced photocatalytic activity at multidimensional interface of 1D-Bi2S3@2D-GO/3D-BiOI ternary nanocomposites for tetracycline degradation under visible-light

Structural dimensionality and surface morphology are key properties that greatly affect the functionalities of materials. Herein, we report a synthesis of dimensionally coupled ternary nanocomposites from three-dimensional (3D) bismuth oxyiodide (BiOI), two-dimensional (2D) graphene oxide (GO), and one-dimensional (1D) bismuth sulfide (Bi₂S₃) nanomaterials for tetracycline degradation under visible-light irradiation. The 2%-Bi₂S₃@1%-GO/BiOI ternary nanocomposites show higher degradation efficiency than neat 3D-BiOI. The coupling of neat 1D-Bi₂S₃ with the 1%-GO/BiOI binary nanocomposite does not increase the specific surface area of the resulting 2%-Bi₂S₃@1%-GO/3D-BiOI ternary nanocomposite, but enhances notably its charge carrier separation and migration, according to the analysis of the higher photocurrent, smaller arc radius of the electrochemical impedance spectroscopy and lower photoluminescence intensity. The observed results suggest that the combination of dimensionally coupled composites provides a synergistic effect through an efficient charge transfer process. This work offers new insights into the design and construction of dimensionally coupled ternary nanocomposites for environmental remediation applications.

Bi-Based Electrode Materials for Alkali Metal-Ion Batteries

Alkali metal (Li, Na, K) ion batteries with high energy density are urgently required for large-scale energy storage applications while the lack of advanced anode materials restricts their development. Recently, Bi-based materials have been recognized as promising electrode candidates for alkali metal-ion batteries due to their high volumetric capacity and suitable operating potential. Herein, the latest progress of Bi-based electrode materials for alkali metal-ion batteries is summarized, mainly focusing on synthesis strategies, structural features, storage mechanisms, and the corresponding electrochemical performance. Particularly, the optimization of electrode-electrolyte interphase is also discussed. In addition, the remaining challenges and further perspectives of Bi-based electrode materials are outlined. This review aims to provide comprehensive knowledge of Bi-based materials and offer a guideline toward more applications in high-performance batteries.

A MoS2@SnS heterostructure for sodium-ion storage with enhanced kinetics

Layered metal sulphides are promising anode materials for sodium-ion batteries (SIBs) and capacitors owing to their distinctive crystal structures and large interlayer spacings, which are suitable for Na⁺ insertion/extraction. However, low electronic conductivity, sluggish ion transfer and large volume variation of metal sulphides during sodiation/desodiation processes have hindered their practical application. In this work, we report the construction of a walnut-like core-shell MoS₂@SnS heterostructure composite as an anode for SIBs with high capacity, remarkable rate and superior cycling stability. Experimental observations and first-principles density functional theory (DFT) calculations reveal that the enhanced electrochemical performances can be mainly ascribed to the boosted charge transfer and ion diffusion capabilities at the heterostructure interface driven by a self-building internal electric field. Our findings herein may pave the way for the development of novel heterostructure composite materials for beyond lithium-ion batteries and capacitors.

Ultrathin rGO-wrapped free-standing bimetallic CoNi2S4-carbon nanofibers: an efficient and robust bifunctional electrocatalyst for water splitting

Electrochemical water splitting represents an ideal strategy for producing clean hydrogen as an energy carrier that serves as an alternative to fossil fuels. As an effective method for hydrogen production, an efficient inexpensive multifunctional electrocatalyst with high durability is designed. Herein, we describe the heterostructural design of a three-dimensional catalytic network with self-embedded CoNi₂S₄ nanograins grown on electrospun carbon nanofibers (CoNi₂S₄-CNFs) with anchored thin-layer reduced graphene oxide. This is achieved via facile electrospinning followed by carbonization, low-temperature sulfidation, and surface functionalization. As a bifunctional catalyst, CoNi₂S₄-CNFs exhibited robust high activity toward the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in an alkaline medium. The anchored ultrathin graphene oxide layer promoted the stability and durability of the catalytic network with an efficient path for the transportation of electrons. The rGO-anchored CoNi₂S₄-CNFs yielded overpotential values of 228 mV and 205 mV for the HER and OER, respectively, that drives a current density of 20 mA cm^-2 in an alkaline medium. Notably, the excellent electrochemical properties are attributed to the functional effect of the CoNi₂S₄ on the CNF network. The ultrathin feature of rGO improved the durability of the catalytic network. Moreover, using the rGO-anchored CoNi₂S₄-CNFs as a cathode and anode in a two-electrode water splitting system required a cell voltage of only 1.55 V to reach a current density of 10 mA cm^-2. These CNFs exhibited outstanding durability for 48 h. The present work offers new insight for the design of a catalytic network with a non-noble metal catalyst that exhibits excellent electrocatalytic activity and durability on the metal sulfides in overall water splitting.

Ultrastable Sodium Storage in MoO3 Nanotube Arrays Enabled by Surface Phosphorylation

Molybdenum trioxide (MoO₃) has been considered as an appealing choice of anode for sodium-ion batteries because of its high theoretical capacity (1117 mA h g^-1). However, the large volume change upon Na⁺ storage results in poor cycling stability and capacity fade of MoO₃. Here, we demonstrate a surface phosphorylation strategy to mitigate the degradation of three-dimensional MoO₃ array electrodes. Such a phosphorylation strategy allows MoO₃ arrays to sustain a capacity of 265 mA h g^-1, or ∼90% of the initial value, at a rate of 2 A g^-1 over 1500 cycles, outperforming most reported MoO₃ electrodes. Moreover, kinetic analysis unveils a capacitance-dominated Na⁺ storage feature of MoO₃ arrays, owing to the enhanced electron mobility imparted by oxygen vacancies that are simultaneously introduced by phosphorylation. Hence, surface phosphorylation might offer new possibilities to bypass multiple materials challenges facing current sodium electrodes.

Asymmetric faradaic assembly of Bi2O3 and MnO2 for a high-performance hybrid electrochemical energy storage device

In the current study, we have explored the coupling of Bi2O3 negative electrode and MnO2 positive electrode materials as an asymmetric faradaic assembly for a high-performance hybrid electrochemical energy storage device (HEESD). Aiming at a low-cost device, both the electrodes have been synthesized by a simple, scalable, and cost-effective chemical synthesis method. After their requisite structure-morphological confirmation and correlation, these electrodes were separately examined for their electrochemical performance in a three-electrode configuration. The results obtained confirm that Bi2O3 and MnO2 exhibit 910 C g-1 and 424 C g-1 specific capacity, respectively, at 2 A g-1 current density. Notably, the performance of both electrodes has been analyzed using Dunn's method to highlight the distinct nature of their faradaic properties. Afterwards, the asymmetric faradaic assembly of both electrodes, when assembled as a HEESD (MnO2//Bi2O3), delivered 411 C g-1 specific capacity at 1 A g-1 current density due to the inclusive contribution from the capacitive as well as the non-capacitive faradaic quotient. Consequently, the assembly offers an excellent energy density of 79 W h kg-1 at a power density of 702 W kg-1, with a magnificent retention of energy density up to 21.1 W h kg-1 at 14 339 W kg-1 power density. Moreover, it demonstrates long-term cycling stability at 10 A g-1, retaining 85.2% of its initial energy density after 5000 cycles, which is significant in comparison with the previously reported literature. Additionally, to check the performance of the device in real time, two HEESDs were connected in series to power a light-emitting diode. The results obtained provide significant insight into hybrid coupling, where two different faradaic electrodes can be combined in a synergistic combination for a high-performance HEESD.

Carbon Quantum Dot-Anchored Bismuth Oxide Composites as Potential Electrode for Lithium-Ion Battery and Supercapacitor Applications

The present investigation elucidates a simple hydrothermal method for preparing nanostructured bismuth oxide (Bi₂O₃) and carbon quantum dot (CQD) composite using spoiled (denatured) milk-derived CQDs. The formation of the CQD-Bi₂O₃ composite was confirmed by UV-vis absorption, steady-state emission, and time-resolved fluorescence spectroscopy studies. The crystal structure and chemical composition of the composite were examined by X-ray diffraction, Fourier transform infrared spectroscopy, Raman spectroscopy, and thermogravimetric analysis. The surface morphology and the particle size distribution of the CQD-Bi₂O₃ were examined using field emission scanning electron microscope and high-resolution transmission electron microscope observations. As an anode material in lithium-ion battery, the CQD-Bi₂O₃ composite exhibited good electrochemical activity and delivered a discharge capacity as high as 1500 mA h g^-1 at 0.2C rate. The supercapacitor properties of the CQD-Bi₂O₃ composite electrode revealed good reversibility and a high specific capacity of 343 C g^-1 at 0.5 A g^-1 in 3 M KOH. The asymmetric device constructed using the CQD-Bi₂O₃ and reduced graphene oxide delivered a maximum energy density of 88 Wh kg^-1 at a power density of 2799 W kg^-1, while the power density reached a highest value of 8400 W kg^-1 at the energy density of 32 Wh kg^-1. The practical viability of the fabricated device is demonstrated by glowing light-emitting diodes. It is inferred that the presence of conductive carbon network has significantly increased the conductivity of the oxide matrix, thereby reducing the interfacial resistance that resulted in excellent electrochemical performances.

Facile synthesis of Sb2S3/MoS2 heterostructure as anode material for sodium-ion batteries

A novel Sb₂S₃/MoS₂ heterostructure in which Sb₂S₃ nanorods are coated with MoS₂ nanosheets to form a core-shell structure has been fabricated via a facile two-step hydrothermal process. The Sb₂S₃/MoS₂ heterostructure utilized as the anode of sodium-ion batteries (SIBs) shows higher capacity, superior rate capability and better cycling performance compared with individual Sb₂S₃ nanorods and MoS₂ nanosheets. Specifically, the Sb₂S₃/MoS₂ electrode shows an initial reversible capacity of 701 mAh g^-1 at a current density of 100 mA g^-1, which then remains at 80.1% of the initial performance after 100 cycles at the same current density. This outstanding electrochemical performance indicates that the Sb₂S₃/MoS₂ heterostructure is a very promising anode material for high-performance SIBs.

Cytotoxicity of biologically synthesised bismuth nanoparticles against HT-29 cell line

This study was purposed to examine the cytotoxicity and functions of biologically synthesised bismuth nanoparticles (Bi NPs) produced by Delftia sp. SFG on human colon adenocarcinoma cell line of HT-29. The structural properties of Bi NPs were investigated using transmission electron microscopy, energy dispersive X-ray, and X-ray diffraction techniques. The cytotoxic effects of Bi NPs were analysed using flow cytometry cell apoptosis while western blot analyses were applied to analyse the cleaved caspase-3 expression. Oxidative stress (OS) damage was determined using the measurement of the glutathione (GSH) and malondialdehyde (MDA) levels and antioxidant activity of superoxide dismutase (SOD) and catalase (CAT) levels. The half maximal inhibitory concentration (IC50) value of Bi NPs was measured to be 28.7 ± 1.4 µg/ml on HT-29 cell line. The viability of HT-29 represented a concentration-dependent pattern (5-80 µg/ml). The mode of Bi NPs induced apoptosis was found to be mainly related to late apoptosis or necrosis at IC50 concentration, without the effect on caspase-3 activities. Furthermore, Bi NPs reduced the GSH and increased the MDA levels and decreased the SOD and CAT activities. Taken together, biogenic Bi NPs induced cytotoxicity on HT-29 cell line through the activation of late apoptosis independent of caspase pathway and may enhance the OS biomarkers.

Exposure and nephrotoxicity concern of bismuth with the occurrence of autophagy

Metal nanoparticles or metal-based compounds have drawn attention in various fields ranging from industry to medicine because of their unique physicochemical properties. Bismuth (Bi) compounds and nanomaterials have been commonly used in alloys, electronic industry, batteries, and as flame retardants as well as for anti- Helicobacter pylori therapy, while the nanomaterial form has great potential for computed tomography imaging and thermotherapy, both of which will be introduced in this review. Although Bi was used for several decades, there is a lack of detailed information concerning their toxicity and mechanisms on human health. We described the toxicity of Bi on the kidney that seemed to be relatively known by researchers, while the mechanisms remain unclear. Recently, our group has found that Bi compounds, including bismuth nitrate (BN) and Bi nanomaterials, can induce autophagy in kidney cells. We also extended our findings by selecting five Bi compounds, and the results showed that BN, bismuth oxychloride, bismuth citrate, colloidal bismuth subcitrate, and Bi nanomaterials all induced slight cytotoxicity accompanied with autophagy. Although the role of autophagy in Bi-induced cytotoxicity and kidney injury is under investigation by us, autophagy may help with the exploration of the mechanisms of nephrotoxicity by Bi.

Heterostructured Bi2S3-Bi2O3 Nanosheets with a Built-In Electric Field for Improved Sodium Storage

Constructing novel heterostructures has great potential in tuning the physical/chemical properties of functional materials for electronics, catalysis, as well as energy conversion and storage. In this work, heterostructured Bi₂S₃-Bi₂O₃ nanosheets (BS-BO) have been prepared through an easy water-bath approach. The formation of such unique BS-BO heterostructures was achieved through a controllable thioacetamide-directed surfactant-assisted reaction process. Bi₂O₃ sheets and Bi₂S₃ sheets can be also prepared through simply modifying the synthetic recipe. When employed as the sodium-ion battery anode material, the resultant BS-BO displays a reversible capacity of ∼630 mA h g^-1 at 100 mA g^-1. In addition, the BS-BO demonstrates improved rate capability and enhanced cycle stability compared to its Bi₂O₃ sheets and Bi₂S₃ sheets counterparts. The improved electrochemical performance can be ascribed to the built-in electric field in the BS-BO heterostructure, which effectively facilitates the charge transport. This work would shed light on the construction of novel heterostructures for high-performance sodium-ion batteries and other energy-related devices.

Enhanced Electrochemical Performances of Bi2O3/rGO Nanocomposite via Chemical Bonding as Anode Materials for Lithium Ion Batteries

Bismuth oxide/reduced graphene oxide (termed Bi₂O₃@rGO) nanocomposite has been facilely prepared by a solvothermal method via introducing chemical bonding that has been demonstrated by Raman and X-ray photoelectron spectroscopy spectra. Tremendous single-crystal Bi₂O₃ nanoparticles with an average size of ∼5 nm are anchored and uniformly dispersed on rGO sheets. Such a nanostructure results in enhanced electrochemical reversibility and cycling stability of Bi₂O₃@rGO composite materials as anodes for lithium ion batteries in comparison with agglomerated bare Bi₂O₃ nanoparticles. The Bi₂O₃@rGO anode material can deliver a high initial capacity of ∼900 mAh/g at 0.1C and shows excellent rate capability of ∼270 mAh/g at 10C rates (1C = 600 mA/g). After 100 electrochemical cycles at 1C, the Bi₂O₃@rGO anode material retains a capacity of 347.3 mAh/g with corresponding capacity retention of 79%, which is significantly better than that of bare Bi₂O₃ material. The lithium ion diffusion coefficient during lithiation-delithiation of Bi₂O₃@rGO nanocomposite has been evaluated to be around ∼10^-15-10^-16 cm²/S. This work demonstrates the effects of chemical bonding between Bi₂O₃ nanoparticles and rGO substrate on enhanced electrochemical performances of Bi₂O₃@rGO nanocomposite, which can be used as a promising anode alterative for superior lithium ion batteries.

Solvothermal synthesis and electrochemical properties of S-doped Bi2Se3 hierarchical microstructure assembled by stacked nanosheets

Hierarchical S-doped Bi₂Se₃ microspheres assembled by stacked nanosheets were successfully synthesized as the anode of a lithium ion battery, which shows an initial discharge capacity of 771.3 mA h g⁻¹ with great potential in energy storage.

The facile preparation of a carbon coated Bi2O3nanoparticle/nitrogen-doped reduced graphene oxide hybrid as a high-performance anode material for lithium-ion batteries

A hybrid of carbon coated Bi₂O₃nanoparticles distributed on nitrogen-doped reduced graphene oxide is prepared by facile thermal treatment processes.