Electrochemical characteristics of Cu/Cu2O/C composite electrode for supercapacitor application

In situ synthesis of europium oxide (Eu2O3) nanoparticles in heteroatom doped carbon nanofibers for boosting the cycling stability of supercapacitors

Maintaining a high specific energy without losing cycling stability is the focus of the supercapacitor field. In this study, carbon nanofibers including europium oxide nanoparticles (CNF/Eu2O3) have been synthesized in the presence of thiourea via a simple approach and applied for the first time as an electrode for SCs. The CNF/Eu2O3-1 electrode doped with nitrogen and sulfur heteroatoms possessed a favorable specific capacitance of 183.2 F g-1, a specific energy of 9.15 W h kg-1, and an excellent capacitance retention of 94.8% even after 10 000 cycles at 1 A g-1. Such excellent performance is ascribed to the surface functionalities, high surface area, and good interaction of Eu2O3 with CNFs. This strategy will provide guidance for other rare element-based electrodes in the field of energy storage.

Metal-Organic Frameworks and Their Derivatives-Based Nanostructure with Different Dimensionalities for Supercapacitors

With the urgent demand for the achievement of carbon neutrality, novel nanomaterials, and environmentally friendly nanotechnologies are constantly being explored and continue to drive the sustainable development of energy storage and conversion installations. Among various candidate materials, metal-organic frameworks (MOFs) and their derivatives with unique nanostructures have attracted increasing attention and intensive investigation for the construction of next generation electrode materials, benefitting from their unique intrinsic characteristics such as large specific surface area, high porosity, and chemical tunability as well as the interconnected channels. Nevertheless, the poor electrochemical conductivity severely limits their application prospects, hence a variety of nanocomposites with multifarious structures have been designed and proposed from different dimensionalities. In this review, recent advances based on MOFs and their derivatives in different dimensionalities ranging from 1D nanopowders to 2D nanofilms and 3D aerogels, as well as 4D self-supporting electrodes for supercapacitors are summarized and highlighted. Furthermore, the key challenges and perspectives of MOFs and their derivatives-based materials for the practical and sustainable electrochemical energy conversion and storage applications are also briefly discussed, which may be served as a guideline for the design of next-generation electrode materials from different dimensionalities.

Role of Electrochemical Techniques for Photovoltaic and Supercapacitor Applications

Electrochemistry forms the base of large-scale production of various materials, encompassing numerous applications in metallurgical engineering, chemical engineering, electrical engineering, and material science. This field is important for energy harvesting applications, especially supercapacitors (SCs) and photovoltaic (PV) devices. This review examines various electrochemical techniques employed to fabricate and characterize PV devices and SCs. Fabricating these energy harvesting devices is carried out by electrochemical methods, including electroreduction, electrocoagulation, sol-gel process, hydrothermal growth, spray pyrolysis, template-assisted growth, and electrodeposition. The characterization techniques used are cyclic voltammetry, electrochemical impedance spectroscopy, photoelectrochemical characterization, galvanostatic charge-discharge, and I-V curve. A study on different recently reported materials is also presented to analyze their performance in various energy harvesting applications regarding their efficiency, fill factor, power density, and energy density. In addition, a comparative study of electrochemical fabrication techniques with others (including physical vapor deposition, mechanical milling, laser ablation, and centrifugal spinning) has been conducted. The various challenges of electrochemistry in PVs and SCs are also highlighted. This review also emphasizes the future perspectives of electrochemistry in energy harvesting applications.

Novel Au nanorod/Cu2O composite nanoparticles for a high-performance supercapacitor

Metal-oxide nanomaterials have attracted great interest in recent years due to their novel characteristics such as surface effect and quantum confinement. A fascinating Au nanorod (NR)/cuprous oxide core-shell composite (AuNR/Cu2O) was directly synthesized using a moderate one-pot facile green redox method and further utilized for energy storage applications in a supercapacitor. The synthesis mechanism is based on the use of reducing agents to form the core shell. The resultant composite was deposited on the surface of nickel foam as a result of redox reactions between Au and Cu via a hydrothermal method. AuNR/Cu2O composite nanoparticles (NPs) were characterized using various spectroscopic and microscopic techniques, including UV-vis and X-ray photoelectron spectroscopies, Brunauer-Emmett-Teller surface area analysis, X-ray diffractometry, and transmission electron microscopy. The AuNR/Cu2O composite NPs grow via the depositing of a 20-50 nm Cu2O shell on an AuNR core with dimensions of 5-20 nm in width and 40-70 nm in length. The as-synthesized AuNR/Cu2O composite NPs were effectively used as electrode materials in a supercapacitor, and their electrochemical performance was determined by cyclic voltammetry, galvanostatic charge-discharge measurements, and electrochemical impedance spectroscopy in 2 M KOH aqueous solution as an electrolyte. The composite NPs showed excellent average specific capacitance of 235 F g-1 at a current density of 2 A g-1 and durable cycling stability (96% even after 10 000 cycles). The higher efficiency of the AuNR/Cu2O composite NPs can be attributed to the presence of AuNR in the core. The AuNR/Cu2O composite NPs exhibit a high surface area and high electrical conductivity, which consequently result in their excellent specific capacitance and outstanding rate as an all-solid-state supercapacitor electrode.