Effect of complexing agent and annealing atmosphere on properties of nanocrystalline ZnS thin films.

The nanocrystalline Zinc Sulfide (ZnS) thin films were prepared on glass substrates by chemical bath deposition (CBD) method using aqueous solutions of zinc acetate, thiourea and tri-sodium citrate in alkaline medium at 80 degrees C. The tri-sodium citrate acts as a complexing agent. The effects of complexing agent and annealing atmosphere (95%N2 + 5%H2S) on structural, morphological and optical properties of ZnS thin films were studied using X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), and optical absorption. XRD study revealed that single phase ZnS powder was formed in the solution with tri-sodium citrate, however, ZnS and ZnO mixed phase powder was formed in the solution without tri-sodium citrate. The films deposited with trisodium citrate showed ZnS with hexagonal wurtzite phase. However, annealed film in (N2 + H2S) atmosphere showed cubic (zincblende) phase. FE-SEM images show that grain size of as-deposited and annealed ZnS films are about 20 nm and 50 nm, respectively. Optical absorption study showed that the films have moderate optical transmission from 65% to 75% in the visible region and the optical band gap energy of as-deposited ZnS film is 3.91 eV and it decreases to 3.73 eV after annealing.

Effect of bath temperature on the properties of nanocrystalline ZnO thin films.

The nanocrystalline zinc oxide (ZnO) thin films have been prepared by chemical bath deposition (CBD) method from aqueous zinc nitrate solution at room temperature (25 degrees C) and at higher temperature (75 degrees C). The changes in structural, morphological and optical properties were studied by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), and optical absorption. The structural studies revealed that the film deposited at room temperature showed mixed phases of ZnO and Zn(OH)2 with wurtzite and orthorhombic crystal structure whereas at higher temperature, the deposited film is ZnO with wurtzite crystal structure. After air annealing at 400 degrees C, all the films converted into pure ZnO with wurtzite crystal structure. The films deposited at room temperature showed fibrous surface morphology with interconnected flakes while films deposited at higher temperature shows well-developed nano-rod morphology. Optical study shows that band gap energy (E(g)) of as-deposited thin films deposited at room temperature and at higher temperature are 3.81 and 3.4 eV, decreases up to 3.20 eV, after annealing treatment.

SILAR deposited iron phosphate as a bifunctional electrocatalyst for efficient water splitting.

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 230 mV and 157 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 1.67 V to deliver a 10 mA cm-2 current density in 1 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.

Direct growth of 2D nickel hydroxide nanosheets intercalated with polyoxovanadate anions as a binder-free supercapacitor electrode.

A mesoporous nanoplate network of two-dimensional (2D) layered nickel hydroxide Ni(OH)2 intercalated with polyoxovanadate anions (Ni(OH)2-POV) was built using a chemical solution deposition method. This approach will provide high flexibility for controlling the chemical composition and the pore structure of the resulting Ni(OH)2-POV nanohybrids. The layer-by-layer ordered growth of the Ni(OH)2-POV is demonstrated by powder X-ray diffraction and cross-sectional high-resolution transmission electron microscopy. The random growth of the intercalated Ni(OH)2-POV nanohybrids leads to the formation of an interconnected network morphology with a highly porous stacking structure whose porosity is controlled by changing the ratio of Ni(OH)2 and POV. The lateral size and thickness of the Ni(OH)2-POV nanoplates are ∼400 nm and from ∼5 nm to 7 nm, respectively. The obtained thin films are highly active electrochemical capacitor electrodes with a maximum specific capacity of 1440 F g-1 at a current density of 1 A g-1, and they withstand up to 2000 cycles with a capacity retention of 85%. The superior electrochemical performance of the Ni(OH)2-POV nanohybrids is attributed to the expanded mesoporous surface area and the intercalation of the POV anions. The experimental findings highlight the outstanding electrochemical functionality of the 2D Ni(OH)2-POV nanoplate network that will provide a facile route for the synthesis of low-dimensional hybrid nanomaterials for a highly active supercapacitor electrode.

A study of median nerve entrapment neuropathy at wrist in uremic patients.

Carpal tunnel syndrome (CTS) is the most common entrapment neuropathy seen in uremic patients. The study was undertaken to estimate the frequency of CTS in uremic patients and to identify the most sensitive electrodiagnostic test. Study was conducted on 80 subjects of age 30-60 years. End-stage kidney disease patients were recruited for the clinical evaluation, motor nerve conduction studies (NCS), sensory NCS, F wave study and median-versus-ulnar comparison studies (palm-to-wrist mixed comparison study, digit 4 sensory latencies study and lumbrical-interossei comparison study). Among three different diagnostic modalities, frequency of CTS was found to be 17.5% with clinical evaluation, 15% with routine NCS studies and 25% with median-versus-ulnar comparison studies. Among the median-versus-ulnar comparison studies, lumbrical-interossei comparison study was found to be most sensitive (90%). The comparative tests for CTS are more sensitive compared to routine NCS and clinical examination. Among the comparative tests, lumbrical-interossei comparison study is the most sensitive. Early diagnosis of CTS may help patients of uremia to seek proper treatment at an appropriate time.