Nanostructures in Dye-Sensitized and Perovskite Solar Cells

Due to increase of attention in energy and environmental concerns, there has been much interest developed in clean and renewable energy technologies. The utilization of green and eco-friendly sunlight through solar cells like photovoltaic cells, photo-electrochemical cells, and dye-sensitize and perovskite solar cells (DSSCs and PSCs) produces energy demand. Due to high electron mobility, suitable band alignment, and high optical transparency, the binary and ternary transition metal oxide materials such as TiO2, SnO2, ZnO, WO3, Bi2O3 and SrTiO3, Zn2SnO4, BaSnO3, etc. have attracted considerable attention as DSSC and PSC electrode materials. Highly efficient solar cells with sustainable performance under severe mechanical deformations are in great demand in forming wearable power supply devices, essential for space technologies. In this regard, myriads of studies have progressed in developing the said metal oxides by various means of nanostructure forms. The aim of this chapter is to highlight research background, basic concepts, operating parameters, working principles, theoretical aspects, and selection of materials with essential properties for DSSCs and PSCs applications

Hydrogen Evolution Reaction Activities of Room-Temperature Self-Grown Glycerol-Assisted Nickel Chloride Nanostructures

Three-dimensional nanomaterials of desired structural/morphological properties and highly porous with a high specific surface area are important in a variety of applications. In this work, glycerol-mediated self-growth of 3-D dandelion flower-like nickel chloride (NiCl2) from nickel-foam (NiF) is obtained for the first time using a room-temperature (27 °C) processed wet chemical method for electrocatalysis application. Glycerol-mediated self-grown NiCl2 flowers demonstrate an excellent electrocatalytic performance towards the hydrogen evolution reaction (HER), which is much superior to the NiF (303 mV) and NiCl2 electrode prepared without glycerol (208 mV) in the same electrolyte solution. With a Tafel slope of 41 mV dec−1, the NiCl2 flower electrode confirms improved reaction kinetics as compared to the other two electrodes, i.e., NiF (106 mVdec−1) and NiCl2 obtained without glycerol (56 mV dec−1). The stability of the glycerol-based NiCl2 electrode has further been carried out for 2000 cycles with the overpotential diminution of just 8 mV, approving an electrocatalyst potential of glycerol-based NiCl2 electrode towards HER kinetics. This simple and easy growth process involves nucleation, aggregation, and crystal growth steps for producing NiCl2 nanostructures for electrocatalytic water splitting application through the HER process

DFT-study supported synergistic electrochemical supercapacitor performance of Bi2MoS6 nanosheets

Synergistic electrochemical performance of the bismuth molybdenum sulphide (Bi2MoS6, BMS) nanosheets can be beneficial for fast ion exchange kinetics in electrolyte solution for energy storage performance. Bismuth sulphide (Bi2S3, BS), molybdenum sulphide (MoS2, MS), and BMS electrode materials of different morphologies are grown on stainless-steel (SS) conducting substrate using a wet chemical process. A 0 - 1 V operating potential window vs. Ag/AgCl has been utilized for half-cell analysis wherein, 947.4 F g- 1 specific capacitance is obtained for BMS nanosheet-like electrode at 0.6 Ag-1 current density with nearly 97 % stability which is better than BS and MS electrode materials. Full understanding of synergistic effect i.e., enhancement of electrochemical properties, has clearly been revealed by applying ab-initio theoretical calculations using density functional theory. The values of power density and energy density of the as-constructed symmetric supercapacitor device by using BMS electrode are respectively found to be 1130 Wkg- 1 and 85 Whkg- 1. A panel of forty-two LEDs coupled in series has been powered through symmetric device to demonstrating the practical application of the asprepared nanosheet-type BMS electrode material for commercial feasibility

An Overview of Self-Grown Nanostructured Electrode Materials in Electrochemical Supercapacitors

Increasing demand for portable and wireless electronic devices with high power and energy densities has inspired global research to investigate, in lieu of scarce rare-earth and expensive ruthenium oxide-like materials, abundant, cheap, easily producible, and chemically stable electrode materials. Several potential electrode materials, including carbon-based materials, metal oxides, metal chalcogenides, layered metal double hydroxides, metal nitrides, metal phosphides, and metal chlorides with above requirements, have been effectively and efficiently applied in electrochemical supercapacitor energy storage devices. The synthesis of self-grown, or in-situ, nanostructured electrode materials using chemical processes is well-known, wherein the base material itself produces the required phase of the product with a unique morphology, high surface area, and moderate electrical conductivity. This comprehensive review provides in-depth information on the use of self-grown electrode materials of different morphologies in electrochemical supercapacitor applications. The present limitations and future prospects, from an industrial application perspectives, of self-grown electrode materials in enhancing energy storage capacity are briefly elaborated

Bismuth oxide-doped graphene-oxide nanocomposite electrode for energy storage application

Nanocrystalline and porous bismuth oxide-doped graphene oxide nanocomposite (Bi2O3-GO NC) electrode material synthesized via microwave irradiation method has been envisaged for supercapacitor application. Surface morphology, elemental configuration, phase purity, surface area, porosity, and binding energy etc., are initially screened and then preferred in electrochemical measurement analysis. The as-obtained Bi2O3-GO NC electrode adduces a better performance with quasi-faradaic redox reactions in electrochemical measurements over pristine GO in 6 M KOH electrolyte solution. The specific capacitance of the Bi2O3-GO NC electrode measured at current densities 5-14 A/g is varied from 1250 to 933 F/g. The as-assembled Bi2O3-GO//Bi2O3-GO symmetric supercapacitor device reveals an exceptional electrochemical performance with 25.83 W-h/kg specific energy at 337 W/kg specific power, and excellent stability of about 80% for 5000 cycles, evidencing usability potential of meta

Synthesis of nickel-copper composite with controllable nanostructure through facile solvent control as positive electrode for high-performance supercapacitors

The surface characteristics of electrodes vary depending on the solvent used. Furthermore, electrochemical performance varies depending on the surface morphology of the electrode. In this study, we grew 3D binary NiCu-based composites on Ni foam, via a binder-free hydrothermal method, for use as a cathode in high-performance supercapacitors. We employed different solvents to prepare the electrodes by adjusting the ratio of deionized water (DI water) to methanol. The electrode prepared using DI water as the solvent had the largest surface area with a nanowire structure. This morphology allowed for good electrical performance by greatly improving the electrode and electrolyte contact area and shortening the ion diffusion path. The optimized deposition of NiCu(CO3)(OH)(2) nanowires (50 mL of DI water as solvent) showed an excellent maximum specific capacity of 758.9 mA h g(-1) at a current density of 3 A g(-1), as well as outstanding cycling performance with 87.2% retention after 5000 cycles. In this work, we focused on the large specific surface area and suitable electrochemical properties of NiCu(CO3)(OH)(2) electrodes with various solvents. As a result, the asymmetric supercapacitor (ASC) using the NiCu(CO3) (OH)(2) electrode prepared with 50 ml of DI water as the solvent as the positive electrode and graphene as the negative electrode, exhibited an energy density of 26.7 W h kg(-1) at a power density of 2534 W kg(-1), and excellent cycling stability with 91.3% retention after 5000 cycles. The NiCu(CO3)(OH)(2)//graphene ASC could turn on an LED light and demonstrated better electrical performance than most previously reported nickel- and copper-based carbonate hydroxide ASCs. In addition, in the present scenario where many nanoscale studies are conducted, a method of controlling the nanostructure of a material through facile solvent control will be of great help to many researchers

Ultra-rapid chemical synthesis of mesoporous Bi2O3 micro-sponge-balls for supercapattery applications

Polycrystalline and mesoporous bismuth oxide (Bi2O3) micro-sponge-balls of 4-7 mu m in diameter comprising of 58-65 (+/- 2) nm upright standing petals, separated by 100-700 (+/- 50) nm crevices, are synthesized directly onto 3D Ni-foam at room-temperature (27 degrees C) using Tritonx-100 surfactant-mediated soft wet chemical method. After knowing the phase purity, surface area, pore-size distribution, micro-sponge-ball-type surface morphology, elemental analysis and binding energy confirmations of Bi2O3, a material with quasi-faradaic redox reactions responsible for supercapattery type behavior, are measured and explored. At a low scan rate, the specific capacitance of Bi2O3 sponge-ball electrode, measured from 0.4 to 1.80 A g(-1) current density, decreases from 559 to 211 F g(-1) which is equivalent to a capacity from 155 to 58 mAh.g(-1). An asymmetric supercapacitor (ASC) device assembly of Bi2O3 sponge-ball electrode with graphite i.e. Bi2O3//graphite demonstrates excellent electrochemical properties with 8 Wh kg(-1) energy density at 2040 W kg(-1) power density, and about 80% cycling retention over 5000 redox cycle operations. A demonstration of LED with full-bright intensity during discharge process of the Bi2O3//graphite ASC device suggests its practical potentiality and industrial viability. (C) 2018 Elsevier Ltd. All rights reserved

Bismuth Oxychloride/MXene symmetric supercapacitor with high volumetric energy density

Since the discovery of two-dimensional (2D) graphene, a new class of 2D materials with excellent electrical conductivity has recently been attracting attention in studying promising electrode materials in energy storage applications. Herein, bismuth oxychloride nanosheets-immobilised Ti3C2Tx MXene material (TCBOC) is synthesised by a facile and cost-effective chemical bath deposition (CBD) route. The bismuth oxychloride (BiOCl) nanosheets are grown and immobilised on surfaces of Ti3C2Tx-MXene flakes. An electrode based on the TCBOC nanocomposite exhibited a remarkably volumetric specific capacitance of 396.5 F cm(-3) at 1 A g(-1) and 228.0 F cm(-3) at 15 A g(-1). Furthermore, a symmetric supercapacitor (SSC) assembled using TCBOC material proves to have a high energy density of 15.2 Wh kg (-1) at a power density of 567.4 Wkg (-1) compared to SSCs using previously reported Ti3C2Tx MXene materials. The SSC shows cycle life retention of 85.0% after 5000 cycles (at 5 A g(-1)). The enhanced capacitive performance is attributed to the increased surface area due to BiOCl nanosheets anchored on a 2D MXene surface, the activities of BiOCl sheets, and the excellent conductivity of a Ti3C2Tx MXene material. (C) 2018 Elsevier Ltd. All rights reserved