Browsing by Author "Azad U.P."
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Item Emerging 3D nanomaterials as electrocatalysts for water splitting reactions(Elsevier Ltd, 2024) Kumari R.; Sammi A.; Shubhangi; Srivastava A.; Azad U.P.; Chandra P.Electrochemical water splitting is an ideal alternative to obtain hydrogen, which is a renewable and clean source of energy with a high calorific value. Designing a highly stable and affordable catalyst is a critical need for achieving the desired electrocatalytic efficacy. Three-dimensional (3D) nanomaterials (NMs) have a hierarchical or interconnected network or framework-like structure with commendable mechanical stability. They possess large surface area and electroactive sites, which have garnered immense scientific interest in the past few years. Different 3D NMs that have been used for electrocatalysis of water are the central focus of this review. There are only a handful of reports discussing them in the literature, but none of them comprehensively cover various 3D NMs as water-splitting catalysts. In addition, the basic concepts of hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), as well as various metrics affecting water splitting kinetics, have been highlighted in detail. In the end, hurdles in the design and commercialization of highly stable water-splitting catalysts and their possible remedies have been discussed along with. � 2024 Hydrogen Energy Publications LLCItem Engineered Ni�Fe prussian blue analogue nanocubes and their transformation into nanocages and mixed oxide for applications as bifunctional electrocatalyst(Elsevier Ltd, 2024) Pal S.; Jana S.; Singh D.K.; Ganesan V.; Azad U.P.; Prakash R.3D nanostructured Prussian blue analogues (PBA) are promising candidates in the family of metal-organic frameworks (MOFs) for applications as bifunctional electrocatalysts due to their open framework structures, high specific surface areas and variable metal active sites. Due to their facile synthesis approach and unique framework structures, these nanostructures can be easily transformed into different structures/materials having different compositions. Herein, we have synthesized Ni�Fe Prussian blue analogue nanocubes (NiFe-PBA-NC) via a simple precipitation method and converted them into Ni�Fe Prussian blue analogue nanocages (NiFe-PBA-NG) and porous mixed metal oxide (NiFe-oxide). For the conversion of nanocubes to nanocages a very controlled etching process is carried out by using an ammonia solution while for the formation of porous mixed metal oxide, nanocubes are annealed in the presence of air. The transformation of nanocubes to nanocages and mixed metal-oxide is thoroughly characterized by various spectroscopic and microscopic techniques and employed as a bifunctional electrocatalyst for oxygen evolution and oxygen reduction reactions (OER and ORR, respectively) in which NiFe-oxide proved to be the best bifunctional catalyst. This thorough and systematic study reveals the fundamentals of the structure-property co-relation towards engineering novel bifunctional electrocatalysts. � 2023 Hydrogen Energy Publications LLCItem Fabrication of Advanced Nanohybrid Materials and Their Deployment in Electrochemical Sensing of Diverse Analytes(Springer Science and Business Media B.V., 2024) Singh N.; Azad U.P.; Srivastava A.; Kumari R.; Prasad R.; Chandra P.The term �nanohybrid� materials refers to materials made of artificial organic and inorganic components joined at the nanoscale level in a covalent or non-covalent way. The contribution of the inorganic groups, that act as functional groups raises the chemical reactivity of the organic basis material. At the vanguard of a new discipline that combines material science, biology, and nanotechnology is the creation of these novel materials. This is an interdisciplinary subject that is at the forefront of technological development. The hybrid material�s remarkable multifunctionality is enhanced by its nanoscale size, structure, shape, and surface chemistry. In recent years, electrochemical biosensor design has evolved to include a range of nanohybrid materials (NHMs) for target analyte detection. Electrochemical biosensors based on NHMs provide better analytical performance in terms of fast reaction times, reasonably priced transducer surface designs, and extended stability. This chapter focuses on the fabrication of several advanced nanohybrid materials and their implementation in the electrochemical sensing of diverse analytes. Potential directions for future research include investigating novel materials to create a new and smart nanohybrid materials-based platform with unique and remarkable features. � The Author(s), under exclusive license to Springer Nature Switzerland AG 2024.Item Lanthanum-based double perovskite oxides as cobalt-free catalyst for bifunctional application in electrocatalytic oxygen reactions(Elsevier Ltd, 2024) Singh D.P.; Mukherjee S.; Bhagat S.; Singh N.; Singh M.; Singh A.K.; Singh A.K.; Azad U.P.; Singh S.; Lalrintluangi; Singh V.P.Electrochemical water splitting by use of suitable electrocatalysts is an important process to establish water as sustainable energy material. Similarly, the Oxygen reduction reaction is an important step involved in fuel cells. Hence, suitable catalysts are required for low-cost and high-performance activity towards both processes. In this work, we synthesized Cobalt-free Lanthanum-based double Perovskites oxides La0.5Sr0.5Fe0.8Cu0.2O3 and La0.5Sr0.5Fe0.8Zn0.2O3 by sol-gel method followed by calcination at different temperatures (800 �C, 900 �C and 1000 �C). Prepared double Perovskite oxide materials exhibit bifunctional catalytic activity towards both oxygen evolution reaction and oxygen reduction reaction. Calcination temperatures and composition have a significant impact on catalytic performance because of morphological control along with tuning of surface composition. Powder X-ray diffraction study has been performed to characterize the materials and phases/composition of materials was further analyzed by Rietveld refinement. The morphology of the best catalyst was analyzed by SEM, EDS mapping and XPS analysis. The catalytic performances of the catalysts were examined using electrochemical methods such as linear sweep voltammetry, cyclic voltammetry and electrochemical impedance spectroscopy in 0.1 M KOH solution. Preparation of noble-metal/cobalt-free catalysts is important finding towards establishing water as potential source for hydrogen production. � 2023 Hydrogen Energy Publications LLCItem Modulation of catalytic activity of BSCF towards electrochemical oxygen reactions using different synthetic approaches(Elsevier Ltd, 2024) Bhagat S.; Singh N.; Singh M.; Singh A.K.; Singh S.; Azad U.P.; Singh A.K.This study is focused on the synthesis of the perovskite oxide materials, particularly Ba0.5Sr0.5Co0.8Fe0.2O3-?, using different synthetic approaches (sol-gel and co-precipitation techniques) and different complexing agents and fuels and their applications for electrochemical water splitting and fuel cells. Prepared perovskite oxide materials exhibits dual catalytic behaviour as it shows the catalytic activity toward the oxygen evolution and reduction reactions in alkaline solution. The Ba0.5Sr0.5Co0.8Fe0.2O3-? electrocatalyst exhibits remarkable efficiency and durability for the OER in basic electrolytes, with a Tafel slope of 70.38 mV/dec for Best catalyst. The best ORR activity observed for Ba0.5Sr0.5Co0.8Fe0.2O3-? synthesized using citric acid shows Tafel slope of 356.43 mV/dec. These oxide materials also show enhanced efficiency in capacitive applications. Additionally, the prepared perovskite oxide materials have been characterized by Powder X-ray diffraction, Le-Bail refinement, scanning electron microscopy, Energy dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy analysis, and high-resolution Transmission Electron Microscopy. Electrochemical techniques such as linear sweep voltammetry, cyclic voltammetry, and electrochemical impedance spectroscopy techniques were used to assess the catalytic performance of the prepared electrocatalysts in 0.1M KOH solution. � 2024 Hydrogen Energy Publications LLC
