Antimonene nanosheets with enhanced electrochemical performance for energy storage applications

Fabrication and Characterization of Silicon-Based Antimonene Thin Film via Electron Beam Evaporation

Antimonene has attracted much attention due to its excellent characteristics of high carrier mobility, thermoelectric properties and high stability. It has great application prospects in Q-switched lasers, laser protection and spintronics. At present, the epitaxy growth of antimonene mainly depends on molecular beam epitaxy. We have successfully prepared antimonene films on silicon, germanium/silicon substrates for the first time using electron beam evaporation coating and studied the effects of the deposition rate and substrate on the preparation of antimonene; film characterization was performed via confocal microprobe Raman spectroscopy, via X-ray diffraction and using a scanning electron microscope. Raman spectroscopy showed that different deposition rates can lead to the formation of different structures of antimonene, such as α phase and β phase. At the same time, it was found that the growth of antimonene is also affected by different substrates and ion beams.

Solution-Processed Sb2S3-Based Heterojunction for Self-Powered Broad Band Weak Light Detection

Antimony sulfide (Sb2S3) has recently regained the attention of photovoltaic researchers as a promising solar absorber; however, its application for the detection of white light remains relatively unexplored. Herein, we report on the self-powered heterojunction photodetector based on a device-grade Sb2S3 film made at low temperature with solution processing. The Sb2S3 absorber film was prepared by single-step spin coating of a novel precursor ink using antimony trichloride as the antimony source along with the low melting thioacetamide as the sulfur source in 2-methoxyethanol, a low boiling environmentally friendly solvent. A simple TiO2/Sb2S3 heterojunction device made by using the film shows a power conversion efficiency of 1.22% without any hole transporting layer. Interestingly, the self-powered photodetector performance of the device under white light exhibits a high on/off ratio of 2.2 × 104 under 1 sun illumination. Moreover, this optical filter-free ultraviolet-visible absorbing near-infrared blind photodetector is equally capable of detecting both strong and weak white light, with a response time of 98 ms. Further, an example of the real-life application of the device is successfully demonstrated by constructing a weak light-detecting sunlight tracking system.

An emissive charge-transfer excited-state at the well-defined hetero-nanostructure interface of an organic conjugated molecule and two-dimensional inorganic nanosheet

Precise engineering of excited-state interactions between an organic conjugated molecule and a two-dimensional semiconducting inorganic nanosheet, specifically the manipulation of charge-transfer excited (CTE) states, still remains a challenge for state-of-the-art photochemistry. Herein, we report a long-lived, highly emissive CTE state at structurally well-defined hetero-nanostructure interfaces of photoactive pyrene and two-dimensional MoS2 nanosheets via an N-benzylsuccinimide bridge (Py-Bn-MoS2). Spectroscopic measurements reveal that no charge-transfer state is formed in the ground state, but the locally-excited (LE) state of pyrene in Py-Bn-MoS2 efficiently generates an unusual emissive CTE state. Theoretical studies elucidate the interaction of MoS2 vacant orbitals with the pyrene LE state to form a CTE state that shows a distinct solvent dependence of the emission energy. This is the first example of organic-inorganic 2D hetero-nanostructures displaying mixed luminescence properties by an accurate design of the bridge structure, and therefore represents an important step in their applications for energy conversion and optoelectronic devices and sensors.

Nanohybrid of antimonene@Ti3C2Tx-based electrochemical aptasensor for lead detection

Lead ions (Pb2+), as one of many common heavy metallic environmental pollutants, can cause serious side-effects and result in chronic poisoning to people's health, so it is highly significant to monitor Pb2+ efficiently and sensitively. Here, we proposed an antimonene@Ti3C2Tx nanohybrid-based electrochemical aptamer sensor (aptasensor) for high sensitive Pb2+ determination. The sensing platform of nanohybrid was synthesized by ultrasonication, possessing the advantages of both antimonene and Ti3C2Tx, which not only can vastly enlarge the sensing signal of the proposed aptasensor, but also greatly simplified its manufacturing flow, because antimonene can strongly interact with aptamer through noncovalently bound. The surface morphology and microarchitecture of the nanohybrid were perused by several methods such as scanning electron microscope (SEM), energy-dispersive X-ray mapping spectroscopy (EDS), transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and atomic force microscope (AFM). Under optimal empirical conditions, the proposed aptasensor exhibited a wide linear correlation of the current signals with the logarithm of CPb2+ (Log CPb2+) over the span from 1 × 10-12 to 1 × 10-7 M and provided a trace discernment limit of 3.3 × 10-13 M. Moreover, the constructed aptasensor displayed superior repeatability, great consistency, eminent selectivity, and beneficial reproducibility, implying its extreme potential application for water quality control and the environmental monitoring of Pb2+.

Enhanced electrochemical performance of the MoS2/Bi2S3 nanocomposite-based electrode material prepared by a hydrothermal method for supercapacitor applications

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.

Research progress of two-dimensional antimonene in energy storage and conversion

Since the first proposal of antimonene in 2015, extensive research attention has been drawn to its application in energy storage and conversion because of its excellent layered structure and fast ion diffusion properties. However, in contrast to the revolutionary expansion of antimonene-based energy devices, reviews on this topic that summarize and further guide the design of 2D antimonene for energy storage and conversion are rare. In this review, the structure, physicochemical properties, and popular synthesis approaches of antimonene are first summarised. Specifically, the rational design and application of antimonene in energy storage and conversion such as electrochemical batteries and supercapacitors, electrocatalytic hydrogen evolution reaction, electrocatalytic oxygen evolution reaction, electrocatalytic carbon dioxide reduction, photocatalytic reduction of organic pollution, photocatalytic reduction of carbon dioxide (CO₂), solar cells and photovoltaic devices are outlined. Finally, opportunities and challenges are presented to further advance the development and application of antimonene in energy conversion and storage.

Two-Dimensional Sb Modified TiO2 Nanorod Arrays as Photoanodes for Efficient Solar Water Splitting

As one of the widely studied semiconductor materials, titanium dioxide (TiO₂) exhibits high photoelectrochemical (PEC) water-splitting performance as well as high chemical and photo stability. However, limited by a wide band gap and fast electron-hole recombination rate, the low solar-to-hydrogen conversion efficiency remains a bottleneck for the practical application of TiO₂-based photoelectrodes. To improve the charge separation and water oxidation efficiency of TiO₂ photoanodes, antimonene, a two-dimensional (2D) material obtained by liquid-phase exfoliation, was assembled onto TiO₂ nanorod arrays (TNRAs) by a simple drop-coating assembly process. PEC measurements showed that the resulting 2D Sb/TiO₂ photoelectrode displayed an enhanced photocurrent density of about 1.32 mA cm^-2 in 1.0 M KOH at 0.3 V vs. Hg/HgO, which is ~1.65 times higher than that of the pristine TNRAs. Through UV-Vis absorption and electrochemical impedance spectroscopy measurements, it was possible to ascribe the enhanced PEC performances of the 2D Sb/TiO₂ photoanode to increased absorption intensity in the visible light region, and improved interfacial charge-transfer kinetics in the 2D Sb/TiO₂ heterojunction, which promotes electron-hole separation, transfer, and collection.

In Situ Binder-Free and Hydrothermal Growth of Nanostructured NiCo2S4/Ni Electrodes for Solid-State Hybrid Supercapacitors

Herein, we report a comparison of the electrochemical performance of two kinds of NiCo2S4-based electrodes for solid-state hybrid supercapacitors (HSCs). For the binder-free electrode, NiCo2S4 was grown on Ni foam by the chemical bath deposition (CBD) method. For the binder-using electrode, NiCo2S4 powder was synthesized by the hydrothermal method. FESEM images depicted the hierarchical nanostructure of NiCo2S4 synthesized by the hydrothermal method and uniform distribution of nanostructured NiCo2S4 grown on Ni foam by the CBD method. Half-cell studies of both NiCo2S4 electrodes showed them exhibiting battery-type charge storage behavior. To assemble HSCs, NiCo2S4 and activated carbon were used as a positive and negative electrode, respectively. Electrochemical studies of the HSCs showed that the accessible potential window was wide, up to 2.6 V, through cyclic voltammetry (CV) analysis. Chronopotentiometry (CP) studies revealed that the energy and power densities of binder-using HSC were 51.24 Wh/kg and 13 kW/kg at 1 Ag−1, respectively, which were relatively higher than those of the binder-free HSC. The binder-free HSC showed 52% cyclic stability, relatively higher than that of the binder-using HSC. Both HSCs, with unique benefits and burdens on energy storage performance, are discussed in this work.

Broadband saturated absorption properties of bismuthene nanosheets

The nonlinear absorption properties of two-dimensional bismuthene nanosheets have great value for application in the photonics field. In this work, bismuthene nanosheets with a thickness of around 4 nm were prepared using the liquid phase exfoliation (LPE) method. The infrared waveband nonlinear absorption properties of bismuthene nanosheets were investigated using the open aperture Z-scan technique with four wavelengths of 950, 1064, 1200, and 1500 nm, respectively. Bismuthene nanosheets exhibited broadband saturated absorption (SA) properties at the infrared band. The lower saturated intensity indicated the advantages of bismuthene as a saturated absorber in the application of ultra-fast lasers in the infrared band.

Bismuthene nanosheets were exfoliated by the LPE method. And the SA properties have been studies by open aperture Z-scan method. The results showed bismuthene nanosheets display broadband saturated properties in near-infrared wavelengths.