Superior supercapacitor performance of Bi2S3 nanorod/reduced graphene oxide composites

Facile Synthesis of a Pyrovanadate Ni2V2O7 Hollow Sphere/Reduced Graphene Oxide Nanocomposite as a Solid-State Hybrid Supercapacitor

Nickel pyrovanadate (NVO) and compositing rGO in different concentrations with NVO are synthesized via the solvothermal process. XRD patterns reveal the formation of crystalline NVO and amorphous rGO in the nanocomposite. The morphology of the material resembles the formation of an NVO hollow nanosphere through a template-free synthesis route with the effect of ethylene glycol. From the CV oxidation and reduction curve, the battery-type faradic reaction is observed. The specific surface area increment via the rGO concentration increment in nanocomposites is due to the partially encapsulated hollow sphere on the 2D active surface area of rGO owing to better specific capacitance and electrochemical stability. In addition, the maximum specific capacitance of 3807 F g-1 at 1 A g-1 for NVO@rGO 20 is obtained via a three-electrode system. The solid-state device shows the specific capacitance retention of ∼70% even after 10,000 cycles for a scan rate of 10 A g-1. The liquid electrolyte device shows the specific capacitance retention of ∼90% from its initial value and the successive charge-discharge process seen over the 10,000 cycles for the scan rate 10 A g-1. The suitable device is identified from this work in terms of high stability, high specific capacitance, and excellent reversibility for electrochemical performance.

Solid state engineering of Bi2S3/rGO nanostrips: an excellent electrode material for energy storage applications

The study presents a novel, one-pot, and scalable solid-state reaction scheme to prepare bismuth sulphide (Bi2S3)-reduced graphene oxide (rGO) nanocomposites using bismuth oxide (Bi2O3), thiourea (TU), and graphene oxide (GO) as starting materials for energy storage applications. The impact of GO loading concentration on the electrochemical performance of the nanocomposites was investigated. The reaction follows a diffusion substitution pathway, gradually transforming Bi2O3 powder into Bi2S3 nanostrips, concurrently converting GO into rGO. Enhanced specific capacitances were observed across all nanocomposite samples, with the Bi2S3@0.2rGO exhibiting the highest specific capacitance of 705 F g-1 at a current density of 1 A g-1 and maintaining a capacitance retention of 82% after 1000 cycles. The superior specific capacitance is attributed to the excellent homogeneity and synergistic relation between rGO and Bi2S3 nanostrips. This methodology holds promise for extending the synthesis of other chalcogenides-rGO nanocomposites.

Controllable Crystal Growth and Improved Photocatalytic Activity of Porous Bi2O3-Bi2S3 Composite Sheets

Porous Bi₂O₃-Bi₂S₃ composite sheets were constructed through a combinational methodology of chemical bath deposition and hydrothermal reaction. The Na₂S precursor concentration in the hydrothermal solution was varied to understand the correlation between the vulcanization degree and structure evolution of the porous Bi₂O₃-Bi₂S₃ composite sheets. The control of the etching rate of the Bi₂O₃ sheet template and the regrowth rate of Bi₂S₃ crystallites via suitable sulfide precursor concentration during the hydrothermal reaction utilizes the formation of porous Bi₂O₃-Bi₂S₃ sheets. Due to the presence of Bi₂S₃ crystallites and porous structure in the Bi₂O₃-Bi₂S₃ composites, the improved visible-light absorption ability and separation efficiency of photogenerated charge carriers are achieved. Furthermore, the as-synthesized Bi₂O₃-Bi₂S₃ composite sheets obtained from vulcanization with a 0.01M Na₂S precursor display highly enhanced photocatalytic degradation toward methyl orange (MO) dyes compared with the pristine Bi₂O₃ and Bi₂S₃. The porous Bi₂O₃-Bi₂S₃ sheet system shows high surface active sites, fast transfer, high-efficiency separation of photoinduced charge carriers, and enhanced redox capacity concerning their constituent counterparts. This study affords a promising approach to constructing Bi₂O₃-based Z-scheme composites with a suitable microstructure and Bi₂O₃/Bi₂S₃ phase ratio for photoactive device applications.

Preparation and application of a flower-rod-like Bi2S3/Co3O4/rGO/nickel foam supercapacitor electrode

Herein, we have prepared a new nanocomposite Bi2S3/Co3O4/rGO/Ni foam substrate electrode through hydrothermal synthesis and an annealing process.

Selective Electrochemical Sensing Platform Based on the Synergy between Carbon Black and Single-Crystalline Bismuth Sulfide for Rapid Analysis of Antipyretic Drugs

Nanomaterials are of significant interest in acetaminophen (APAP) detection in pharmaceutical samples. Herein, a carbon black/single-crystalline rodlike bismuth sulfide (CB/Bi₂S₃) composite prepared by an ultrasonic method is reported and utilized for the rapid analysis of APAP. The highly oriented edge reactive sites of the CB/Bi₂S₃ composite promoted synergy and good electrochemical sensing performance with a fast electron transfer rate and low overpotential (0.35 V). Therefore, a CB/Bi₂S₃ composite-modified glassy carbon electrode (GCE) was applied to the selective determination of APAP by the voltammetric technique. The CB/Bi₂S₃ composite-modified electrode showed the lowest limit of detection of APAP (1.9 nM) with excellent sensitivity. The proposed CB/Bi₂S₃/GCE platform exhibited high selectivity, excellent stability (87.15%), and reproducibility. Also, the CB/Bi₂S₃/GCE sensor was then successfully used to analyze an APAP pharmaceutical sample and exhibited satisfactory outcomes. Therefore, the CB/Bi₂S₃-modified GCE sensor platform would be a low-cost and robust GCE electrode material for APAP detection.

Bi2 S3 -In2 S3 Heterostructures for Efficient Photoreduction of Highly Toxic Cr6+ Enabled by Facet-Coupling and Z-Scheme Structure

The construction of Z-scheme photocatalyst materials mimicking the natural photosynthesis system provides many advantages, including increased light harvesting, spatially separated reductive and oxidative active sites and strong redox ability. Here, a novel Bi₂ S₃ nanorod@In₂ S₃ nanoparticle heterojunction photocatalyst synthesized through one-pot hydrothermal method for Cr⁶⁺ reduction is reported. A systematic investigation of the microstructural and compositional characteristics of the heterojunction catalyst confirms an intimate facet coupling between (440) crystal facet of In₂ S₃ and (060) crystal facet of Bi₂ S₃ , which provides a robust heterojunction interface for charge transfer. When tested under visible-light irradiation, the Bi₂ S₃ -In₂ S₃ heterojunction photocatalyst with 15% Bi₂ S₃ loading content achieves the highest Cr⁶⁺ photoreduction efficiency of nearly 100% with excellent stability, which is among the best-reported performances for Cr⁶⁺ removal. Further examination using optical, photoelectrochemical, impedance spectroscopy, and electron spin resonance spectroscopy characterizations reveal greatly improved photogenerated charge separation and transfer efficiency, and confirm Z-scheme electronic structure of the photocatalyst. The Z-scheme Bi₂ S₃ -In₂ S₃ photocatalyst demonstrated here presents promise for the removal of highly toxic Cr⁶⁺ , and could also be of interest in photocatalytic energy conversion.

Enhanced electrochemical activities of morphologically tuned MnFe2O4 nanoneedles and nanoparticles integrated on reduced graphene oxide for highly efficient supercapacitor electrodes

The morphology of a nanoparticle strongly controls the path of electronic interaction, which directly correlates with the physicochemical properties and also the electrochemical comportment. Combining it with a two-dimensional (2D) material for a layer-by-layer approach will increase its possibilities in applications such as energy conversion and storage. Here, two different morphologies of MnFe2O4, nanoparticles and nanoneedles, are developed by a facile hydrothermal approach and sandwiched with reduced graphene oxide for constructing a 2D/3D sandwiched architecture. The rGO planar structure with abundant hierarchical short pores facilitates the thorough utilization of the utmost surface area to permeate the electrolyte within the structure to minimize the accumulation of rGO nanosheets laterally. The ferrite composited with rGO manifests high specific capacitance as the EDLC behaviour surpasses the faradaic pseudocapacitance boosting electrical conductivity compared to the as-synthesized MnFe2O4 structures. Benefiting from a 3D structure and the synergetic contribution of the MnFe2O4 nanoneedles and electrically conductive rGO layer, the MnFe2O4 nanoneedles@rGO electrode exhibits a high areal capacitance of 890 mF cm-2 and a remarkable specific capacitance of 1327 F g-1 at a current density of 5 mA cm-2. 93.36% of the initial capacitance was retained after 5000 cycles in 1 mol L-1 Na2SO4 indicating its high cycling stability. The synthesis route proves to be beneficial for a comprehensive yield of MnFe2O4@rGO nanosheets of different morphologies for use in the sophisticated design of energy-storing devices. This research strongly suggests that nanoparticle geometry, in addition to two-dimensional carbon-based materials, is a critical factor in a supercapacitor design.