Zeolitic imidazolate frameworks derived Co-Zn-nanoporous carbon-sulfide material for supercapacitors

Synergistic electrochemical performance of textile sludge based activated carbon with reduced graphene oxide as electrode for supercapacitor application

The procedure for disposing of textile waste sludge requires sustainable solutions due to numerous environmental issues associated with its disposal. The majority of textile manufacturers incinerate the waste sludge to meet their heating demands, which is harmful to the environment. It can also be used in soil amendment, biodegradable products, construction material and water treatment process as absorbent to remove the heavy metals etc. In this study we use the heavy metal containing textile waste sludge as a precursor for the fabrication of functional electrode material for supercapacitor applications. In this process the organic content within the textile sludge waste is treated at 900 °C and transformed into activated carbon, a vital component of supercapacitors electrodes. Through a series of pyrolysis and activation processes, it is further converted into porous activated carbon (AC) with a wide surface area and appropriate electrochemical properties. To enhance the overall conductivity of the electrode material for supercapacitor applications, the carbon content of the material is increased by loading of reduced graphene oxide (rGO) up to 4 wt%. It resulted in a significant increase in the surface area up to 128.68 m2/g. The effective conversion and relevance of the obtained material for supercapacitor applications is further reinforced by the excellent electrochemical performance of rGO@AC-900 °C which generated a specific capacitance of 362F/g with 4 wt% loading which is higher than the specific capacity achieved with lower rGO loading i.e., 83.2 F/g and 182.5 F/g for AC-900 °C and 2 wt% rGO@AC-900 °C, respectively. The 4 wt% rGO@AC900°C also represented improved stability with up to 82 % charge retention after 5000 charge-discharge cycles. The excellent EDLC behavior of 4 wt% rGO@AC900°C is also evident from the impedance data. The electrode material with 4 wt% rGO loading showed lower value of RCT i.e., 4.16 Ω as compared to 12.08 Ω with 2 wt% rGO loading. This novel approach offers a sustainable alternative for the handling of hazardous textile waste sludge through conversion into a potential electrode material for environmentally friendly energy storage devices.

Rational Fabrication of Nickel Vanadium Sulfide Encapsulated on Graphene as an Advanced Electrode for High-Performance Supercapacitors

Supercapacitors (SCs) are widely recognized as competitive power sources for energy storage. The hierarchical structure of nickel vanadium sulfide nanoparticles encapsulated on graphene nanosheets (NVS/G) was fabricated using a cost-effective and scalable solvothermal process. The reaction contents of the composites were explored and optimized. TEM images displayed the nickel vanadium sulfide nanoparticles (NVS NPs) with 20-30 nm average size anchored to graphene nanosheets. The interconnection of graphene nanosheets encapsulating NVS nanoparticles effectively reduces the ion diffusion path between the electrode and electrolyte, thereby enhancing electrochemical performance. The NVS/G composite demonstrated improved electrochemical performance, achieving a maximum of 1437 F g-1 specific capacitance at 1 A g-1, remarkable rate capability retaining of 1050 F g-1 at 20 A g-1, and exceptional cycle stability with 91.2% capacitance retention following 10,000 cycles. The NVS/G composite was employed as a cathode, and reduced graphene oxide (rGO) was used as an anode material to assemble a device. Importantly, asymmetric SCs using NVS/G//rGO achieved 74.7 W h kg-1 energy density at 0.8 kW kg-1 power density, along with outstanding stability with 88.2% capacitance retention following 10,000 cycles. These superior properties of the NVS/G electrode highlight its significant potential in energy storage applications.

Ti3C2Tx MXene reinforcement: a nickel-vanadium selenide/MXene based multi-component composite as a battery-type electrode for supercapacitor applications

Designing innovative microstructures and implementing efficient multicomponent strategies are still challenging to achieve high-performance and chemo-mechanically stable electrode materials. Herein, a hierarchical three-dimensional (3D) graphene oxide (GO) assisted Ti3C2Tx MXene aerogel foam (MXene-GAF) impregnated with battery-type bimetallic nickel vanadium selenide (NiVSe) has been prepared through a hydrothermal method followed by freeze-drying (denoted as NiVSe-MXene-GAF). 3D-oriented cellular pore networks benefit the energy storage process through the effective lodging of NiVSe particles, improving the access of the electrolyte to the active sites, and alleviating volume changes during redox reactions. The 3D MXene-GAF conductive matrix and heterostructured interface of MXene-rGO and NiVSe facilitated the rapid transport of electrical charges and ions during the charge-discharge process. As a result of the synergism of these effects, NiVSe-MXene-GAF exhibited remarkable electrochemical performance with a specific capacity of 305.8 mA h g-1 at 1 A g-1 and 99.2% initial coulombic efficiency. The NiVSe-MXene-GAF electrode delivered a specific capacity of 235.1 mA h g-1 even at a high current density of 12 A g-1 with a 76.8% rate performance. The impedance measurements indicated a low bulk solution resistance (Rs = 0.71 Ω) for NiVSe-MXene-GAF. Furthermore, the structural robustness of NiVSe-MXene-GAF guaranteed long-term stability with a 91.7% capacity retention for successive 7000 cycles. Thus, developing NiVSe-MXene-GAF provides a progressive strategy for fabricating high-performance 3D heterostructured electrode materials for energy storage applications.