Showing papers by "Bhaskar R. Sathe published in 2018"

Enhanced electrocatalytic hydrogen generation from water via cobalt-doped Cu2ZnSnS4 nanoparticles

Abstract: Herein, we adopted a novel noble metal-free Co-doped CZTS-based electrocatalyst for the hydrogen evolution reaction (HER), which was fabricated using a facile, effective, and scalable strategy by employing a sonochemical method. The optimized Co-doped CZTS electrocatalyst shows a superior HER performance with a small overpotential of 200 and 298 mV at 2 and 10 mA−1, respectively, and Tafel slope of 73 mV dec−1, and also exhibits excellent stability up to 700 cycles with negligible loss of the cathodic current. The ease of synthesis and high activity of the Co-doped CZTS-based cost-effective catalytic system appear to be promising for HER catalysis.

Biomass-Mediated Synthesis of Cu-Doped TiO2 Nanoparticles for Improved-Performance Lithium-Ion Batteries.

Abstract: Pure TiO2 and Cu-doped TiO2 nanoparticles are synthesized by the biomediated green approach using the Bengal gram bean extract. The extract containing biomolecules acts as capping agent, which helps to control the size of nanoparticles and inhibit the agglomeration of particles. Copper is doped in TiO2 to enhance the electronic conductivity of TiO2 and its electrochemical performance. The Cu-doped TiO2 nanoparticle-based anode shows high specific capacitance, good cycling stability, and rate capability performance for its envisaged application in lithium-ion battery. Among pure TiO2, 3% Cu-doped TiO2, and 7% Cu-doped TiO2 anode, the latter shows the highest capacity of 250 mAh g-1 (97.6% capacity retention) after 100 cycles and more than 99% of coulombic efficiency at 0.5 A g-1 current density. The improved electrochemical performance in the 7% Cu-doped TiO2 is attributed to the synergetic effect between copper and titania. The results reveal that Cu-doped TiO2 nanoparticles might be contributing to the enhanced electronic conductivity, providing an efficient pathway for fast electron transfer.

Ultrasensitive and bifunctional ZnO nanoplates for an oxidative electrochemical and chemical sensor of NO2: implications towards environmental monitoring of the nitrite reaction

Abstract: Herein, we focused on the one pot synthesis of ZnO nanoplates (NP edge thickness of ∼100 nm) using a chemical emulsion approach for chemical (direct) and electrochemical (indirect) determination of NO2. The structural and morphological elucidation of the as-synthesized ZnO NPs was carried out by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive analysis of X-ray (EDAX), thermogravimetric analysis (TGA) and BET-surface area measurements. The XRD studies of the as-synthesised NPs reveal that ZnO NPs have a Wurtzite type crystal structure with a crystallite size of ∼100 nm. Such ZnO NPs were found to be highly sensitive to NO2 gas at an operating temperature of 200 °C. Electrocatalytic abilities of these ZnO NPs towards NO2/NO2− were verified through cyclic voltammetry (CV) and linear sweep voltammetry (LSV) using aqueous 1 mM NO2− (nitrite) in phosphate buffer (pH 7) solution. The results revealed enhanced activity at an onset potential of 0.60 V vs. RCE, achieved at a current density of 0.14 mA cm−2. These ZnO NPs show selective NO2 detection in the presence of other reactive species including CO, SO2, CH3OH and Cl2. These obtained results show that this chemical route is a low cost and promising method for ZnO NPs synthesis and recommend further exploration into its applicability towards tunable electrochemical as well as solid state gas sensing of other toxic gases.

Bioactive ceramic composite material stability, characterization, and bonding to bone

Abstract: Musculoskeletal conditions are the most commonly occurring medical conditions, and they have a considerable influence on the quality of health and living standard of the millions of people across the world. Annually, around the globe, approximately 2.3 million bone-tissue graft transplants are performed. The bone fracture, osteoporosis, osteoarthritis, and various neoplastic disorders are the common clinical problems related with bone and skeletal system. The common approaches to these bone problems are autografts or allografts. These protocols have certain limitations such as resorption, donor site morbidity, compromised supply, rejection rate up to 50% at some sites, and the risk of inducing transmissible diseases. Consequently, considerable attention has been directed toward the use of bioactive materials as synthetic grafts for bone regeneration. These include hydroxyapatite (HAP), tricalcium phosphate, bioactive glass, and glass ceramics. More significantly, calcium phosphates are the major constituent of bone mineral. The most extensively used synthetic calcium phosphate ceramic for bone replacement is HAP with a chemical formula of Ca 10 (PO 4 ) 6 (OH) 2 . It has Ca:P molar ratio of 1.667 and is regarded as the most stable composition compared to other calcium phosphate ceramic within a pH range of 4.2–8.0. Calcium phosphate cement is one of the most important types of bioceramic material. In combination with various calcium phosphates, an injectable paste can be formed, which is cured over a period of time, in which resultant product is a carbonate apatite. The cements cure in situ and are gradually resorbed and replaced by a newly formed bone. The concept of a bioactive glass was pioneered by Hench and colleagues. The composition of Bioglass is a series of special designed glasses, consisting of a Na 2 O–CaO–SiO 2 glass with the addition of P 2 O 5 , B 2 O 3 , and CaF 2 . A biologically active hydroxycarbonate apatite layer is formed on the surface of bioactive glasses in vitro and in vivo. The chemical properties could be controlled in bioactive glasses and eventually its bonding to tissue. Certain specialized compositions of Bioglass (e.g., 45S5) can bond to soft tissue as well as bone, in either bulk or particulate form. Moreover, apatite-wollastonite glass-ceramic, with an assembly of small apatite particles effectively reinforced by β-wollastonite exhibit not only bioactivity, but also a fairly high mechanical strength. Mechanical properties like the bending strength, toughness against fracture, and Young’s modulus of A-W glass-ceramic are the highest among bioactive glasses and glass-ceramics enabling it to be used in some compression load-bearing applications. Overall, the advantages of bioactive glasses are the magnitude of their surface reactivity and the ability to change the chemical composition, thus facilitating bonding with variety of tissues. Mechanical properties are the drawback as these materials have relatively low bending strength in comparison to other ceramic materials. The bioactive calcium phosphate ceramics, bioglasses, and glass-ceramics form a mechanically strong interfacial bond with bone. The strength of the bond is normally equivalent to or greater than the strength of the host bone, depending on test conditions. Therefore, all of these materials have excellent bioactivity. Nevertheless, bioactive ceramics have a flexural strength, strain-to-failure, and fracture toughness, which is less than the bone and the elastic modulus is greater than the bone. In other words, most bioactive materials have a less-than-optimal biomechanical compatibility when used in load-bearing applications. An approach to mitigate this problem involves designing and structural tailoring of bioactive composites. The concept of matching the mechanical behavior of an implant, with the tissue to be replaced in order to solve the problem of stress shielding of conventional biomaterials, was proposed by Bonfield et al. Thus, the composite approach can significantly meet the challenge of a long life, as a demand for the new-generation implant materials. Calcium phosphate ceramics, bioglasses, and glass ceramics are generally considered to be bone bioactive ceramics. These materials generally get bonded to the surrounding osseous tissue and enhance further bone-tissue formation. The direct bone bonding to bioactive glasses was first observed and reported by Hench et al., since then considerable progress has been made in understanding the basic mechanism of the formation of bone and biomaterial bond and its effect on bone formation.