ABSTRACT
The development of efficient and earth-abundant electrocatalysts for overall water splitting is important but still challenging. Herein, iron phosphate (FePi) electrode is synthesized using a successive ionic layer deposition and reaction (SILAR) method on a nickel foam substrate at room temperature and is used as a bifunctional electrocatalyst for water splitting. The prepared FePi electrodes show excellent electrocatalytic activity and stability for the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). The FePi electrode exhibits low overpotential of 230â¯mV and 157â¯mV towards the OER and HER, respectively, with superior long-term stability. As a result, an electrolyzer that exploits FePi as both the anode and the cathode is constructed, which requires a cell potential of 1.67â¯V to deliver a 10â¯mAâ¯cm-2 current density in 1â¯M KOH solution. The exceptional features of the catalyst lie in its structure and active metal sites, increasing surface area, accelerated electron transport and promoted reaction kinetics. This study may provide a facile and scalable approach to design a high-efficiency, earth-abundant electrocatalyst for water splitting.
ABSTRACT
Present work demonstrates enhanced supercapacitive performance of CoO-rGO electrode using redox electrolyte. The long range electrostatic force developed during deposition of CoO-rGO composite thin film orient the molecules into the hexagonal crystal structure. The incorporated CoO particles into rGO nano-sheets make the structure more porous for the intercalation of the electrolyte ions through the electrode material. Additionally, 0.025â¯Mâ¯K3[Fe(CN)6]â¯+â¯0.025â¯Mâ¯K4[Fe(CN)6] redox couple into KOH electrolyte enhances the supercapacitive performance than bare KOH electrolyte. The maximum specific capacitance of 1005â¯Fâ¯g-1 is observed due to the combined effect of K3[Fe(CN)6] and K4[Fe(CN)6] redox couple into KOH electrolyte. Also, energy density of 86.74â¯Whâ¯kg-1 at power density of 3.54â¯kWâ¯kg-1 suggest potential application of CoO-rGO composite thin film in the development of high energy density supercapacitor based on redox active electrolyte.
ABSTRACT
Cu2SnS3 (CTS) thin films have been successfully deposited on a cost-effective stainless steel substrate by simple and inexpensive chemical bath deposition (CBD) method. The films are deliberated in provisos of their structural, morphological, optical and photoelectrochemical (PEC) properties before and after annealing treatment, using various physico-chemical techniques. The XRD studies showed the formation of triclinic phase of CTS films with nanocrystalline structure. Also, the crystallinity is enhanced with annealing and the secondary phase of Cu2S observed. Raman analysis confirmed the formation of CTS compound with secondary Cu2S phase. The SEM images also discovered mostly tiny spherical grains and significant progress in the size of grains after annealing. The films possess direct transitions with band gap energies of 1.35eV and 1.31eV before and after annealing, respectively. The improved photoconversion efficiency of CTS thin film based PEC cell is explained with the help of theoretical modeling of energy band diagram and correspondent circuit model of the impedance spectra.
ABSTRACT
Low temperature soft chemical synthesis approach is employed towards MoS2 thin film preparation on cost effective stainless steel substrate. 3-D semispherical nano-grain composed surface texture of MoS2 film is observed through FE-SEM technique. Electrochemical supercapacitor performance of MoS2 film is tested from cyclic voltammetry (CV) and galvanostatic charge discharge (GCD) techniques in 1M aqueous Na2SO4 electrolyte. Specific capacitance (Cs) of 180Fg-1 with CV cycling stability of 82% for 1000 cycles is achieved. Equivalent series resistance (Rs) of 1.78Ωcm-2 observed through Nyquist plot shows usefulness of MoS2 thin film for charge conduction in supercapacitor application.
ABSTRACT
Lanthanum telluride (La2Te3) thin films are synthesized via a successive ionic layer adsorption and reaction (SILAR) method. The crystal structure, surface morphology and surface wettability properties are investigated using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Field emission scanning electron microscopy (FE-SEM) and contact angle goniometer techniques, respectively. The La2Te3 material exhibits a specific surface area of 51m2g-1 determined by Brunauer-Emmett-Teller (BET) method. La2Te3 thin film electrode has a hydrophilic surface which consists of interconnected pine leaf-like flaky arrays that affect the performance of the supercapacitor. The supercapacitive performance of La2Te3 film electrode is evaluated in 1M LiClO4/PC electrolyte using cyclic voltammetry, galvanostatic charge-discharge, and electrochemical impedance spectroscopy techniques. La2Te3 film electrode exhibits a specific capacitance of 194Fg-1 at a scan rate of 5mVs-1 and stored energy density of 60Whkg-1 with delivering power density of 7.22kWkg-1. La2Te3 film electrode showed capacitive retention of 82% over 1000cycles at a scan rate of 100mVs-1. Further, flexible La2Te3|LiClO4-PVA|La2Te3 supercapacitor cell is fabricated.
ABSTRACT
The porous honey comb-like La2O3 thin films have been synthesized using one step spray pyrolysis method. The influence of sprayed solution quantity on properties of La2O3 thin films is studied using X-ray diffraction, Fourier transform spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, optical absorption and Brunauer-Emmett-Teller techniques. Morphology of La2O3 electrode is controlled with sprayed solution quantity. The supercapacitive properties of La2O3 thin film electrode are investigated using cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance techniques. The La2O3 film electrode exhibited the specific capacitance of the 166Fg-1 with 85% stability for the 3000 cycles. The La2O3 film electrode exhibited sensitivity of 68 at 523K for 500ppm CO2 gas concentration. The possible CO2 sensing mechanism is discussed.
ABSTRACT
The nanoporous oxide layer is formed on the surface of 304 type stainless steel (SS) by chemical oxidation method. The characterization of the oxide layer is carried out using X-ray photoelectron spectroscopy (XPS), field-emission scanning electron microscopy (FE-SEM), atomic force microscopy (AFM), contact angle and energy-dispersive X-ray spectroscopy (EDS) techniques. The supercapacitive properties of oxide layer are studied using cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance spectroscopy techniques.
ABSTRACT
The facile and low cost simple chemical bath deposition (CBD) method is employed to synthesize red colored selenium thin films. These selenium films are characterized for structural, morphological, topographical and wettability studies. The X-ray diffraction (XRD) pattern showed the crystalline nature of selenium thin film with hexagonal crystal structure. The scanning electron microscopy (SEM) study displays selenium nanoparticles ranging from 20 to 475 nm. A specific surface area of 30.5 m(2) g(-1) is observed for selenium nanoparticles. The selenium nanoparticles hold mesopores in the range of 1.39 nm, taking benefits of the good physicochemical stability and excellent porosity. Subsequently, the electrochemical properties of selenium thin films are deliberated by cyclic voltammetry (CV), galvanostatic charge-discharge and electrochemical impedance spectroscopy (EIS) techniques. The selenium thin film shows specific capacitance (Cs) of 21.98 F g(-1) with 91% electrochemical stability.
ABSTRACT
The green synthesis method is inexpensive and convenient for large area deposition of thin films. For the first time, a green synthesis method for large area silver thin film containing nanoparticles is reported. Silver nanostructured films are deposited using silver nitrate solution and guava leaves extract. The study confirmed that the reaction time plays a key role in the growth and shape/size control of silver nanoparticles. The properties of silver films are studied using UV-visible spectrophotometer, scanning electron microscopy (SEM), X-ray diffraction (XRD), atomic force microscopy (AFM), contact angle, Fourier-transform Raman (FT-Raman) spectroscopy and Photoluminescence (PL) techniques. Finally, as an application, these films are used effectively in antibacterial activity study.
