Browsing by Author "Uday Pratap Azad"

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Catalytic reduction of organic dyes at gold nanoparticles impregnated silica materials: Influence of functional groups and surfactants
(2011) Uday Pratap Azad; Vellaichamy Ganesan; Manas Pal
Gold nanoparticles (Au NPs) in three different silica based sol-gel matrixes with and without surfactants are prepared. They are characterized by UV-vis absorbance and transmission electron microscopic (TEM) studies. The size and shape of Au NPs varied with the organo-functional group present in the sol-gel matrix. In the presence of mercaptopropyl functionalized organo-silica, large sized (200-280 nm) spherical AuNPs are formed whereas in the presence of aminopropyl functionalized organo-silica small sized (5-15 nm) Au NPs are formed inside the tube like organo-silica. Further, it is found that Au NPs act as efficient catalyst for the reduction of organic dyes. The catalytic rate constant is evaluated from the decrease in absorbance of the dyemolecules. Presence of cationic or anionic surfactants greatly influences the catalytic reaction. The other factors like hydrophobicity of the organic dyes, complex formation of the dyes with anionic surfactants, repulsion between dyes and cationic surfactant, adsorption of dyes on the Au NPs also play important role on the reaction rate. © Springer Science+Business Media B.V. 2011.
Determination of hydrazine by polyNi(II) complex modified electrodes with a wide linear calibration range
(2011) Uday Pratap Azad; Vellaichamy Ganesan
Polymeric [NiII(teta)]2+ (poly(Ni); teta = C-meso-(5,5,7,12,12,14-hexamethyl-1,4,8,11-tetra-azacyclotetradecane)) modified glassy carbon and Nafion (Nf)-coated glassy carbon electrodes (GC/poly(Ni) and GC/Nf/poly(Ni), respectively) were used for the efficient electrocatalytic oxidation of hydrazine (HZ) in 0.1 M NaOH. The catalytic currents were proportional to the concentration of HZ with a wide linear calibration range (LCR). GC/poly(Ni) had a LCR from 1.0 μM to 10.0 mM, whereas that of GC/Nf/poly(Ni) ranged from 1.0 μM to 100.0 mM. The latter is the widest LCR reported to date. The presence of the Nf film (i.e., in GC/Nf/poly(Ni)) not only increased the stability of the poly(Ni) film but also widened the LCR. The electrocatalytic oxidation of HZ obeyed first-order kinetics with respect to HZ concentration. The kinetic parameters were investigated by cyclic voltammetry and chronoamperometry. © 2011 Elsevier Ltd. All rights reserved.
Efficient electrocatalytic oxidation and selective determination of isoniazid by Fe(tmphen) 3 2+-exchanged Nafion®-modified electrode
(2012) Uday Pratap Azad; Vellaichamy Ganesan
Cyclic voltammetry and electrochemical impedance studies of Fe(tmphen) 3 2+ (where tmphen=3,4,7,8-tetramethyl- 1,10-phenanthroline)-immobilized Nafion®-modified glassy carbon electrode (GC/Nf/Fe(tmphen) 3 2+) are carried out in 0.1 M Na 2SO 4 solution. Nafion-Fe(tmphen) 3 2+ complex exhibits efficient electrocatalytic oxidation of isoniazid. The linear double reciprocal plot of current and concentration of isoniazid shows a Michaelis-Menten-type catalytic process. The catalytic oxidation currents are proportional to the concentration of isoniazid and show a wide linear calibration range for the quantitative determination of isoniazid. Detection limit and sensitivity are found to be 13 μM and 2.5 μA mM -1, respectively. © Springer-Verlag 2012.
Efficient sensing of nitrite by Fe(bpy)32+ immobilized Nafion modified electrodes
(Royal Society of Chemistry, 2010) Uday Pratap Azad; Vellaichamy Ganesan
Fe(bpy)32+ (where bpy = 2,2' bipyridyl) immobilized Nafion (Nf) modified glassy carbon electrodes were prepared and they showed excellent electrocatalytic oxidation of nitrite (NO2-) which leads to the sensitive determination of NO2-. Electrostatic repulsion between NO2- and Nf film is greatly decreased when Nf film is fully exchanged with cations. © 2010 The Royal Society of Chemistry.
Electrocatalytic oxidation and sensitive determination of glycine at poly(niIIteta) modified electrodes
(American Scientific Publishers, 2013) Uday Pratap Azad; Vellaichamy Ganesan
A new electrocatalyst for the electrocatalytic oxidation of glycine (Gly) is reported. A Glassy carbon electrode (GC) was modified with conductive film of polymeric [NiII(teta)]2+ (represented as GC/poly(Ni); teta = C-meso-5,5,7,12,12,14-hexamethyl-1,4,8,11-tetra-azacyclotetradecane) and used for the electrocatalytic oxidation and sensitive determination of Gly. Cyclic voltammetry and electrochemical impedance studies of the GC/poly(Ni) electrode show improved kinetics for the oxidation of Gly. The catalytic current at the GC/poly(Ni) electrode in presence of different concentrations of Gly is linear in the range 10.0 μM to 5.0 mM with two different slopes. The catalytic oxidation rate constant and diffusion coefficient of Gly are determined using chronoamperometry and chronocoulometry. © 2013 American Scientific Publishers.
Electrochemical determination of nanomolar levels of isoniazid in pharmaceutical formulation using silver nanoparticles decorated copolymer
(Elsevier Ltd, 2016) Pankaj Kumar Rastogi; Vellaichamy Ganesan; Uday Pratap Azad
A copolymer of methyl methacrylate and 2-acrylamido-2-methylpropane sulfonic acid (P(MMA-co-AMPS)) and silver nanoparticles (Ag NPs) incorporated P(MMA-co-AMPS) (Ag-P(MMA-co-AMPS)) are used to construct efficient electrochemical sensing platforms (ESPs) to quantitatively determine isoniazid (INZ) at neutral pH conditions. Cyclic voltammetry, amperometry and electrochemical impedance spectroscopy are used as diagnostic tools for INZ determination at these ESPs in pH 7.0 phosphate buffer solution. It has been found that P(MMA-co-AMPS) copolymer facilitates the INZ oxidation with improved electrochemical behaviors. At Ag-P(MMA-co-AMPS), electrochemical characteristics of INZ is much improved than at P(MMA-co-AMPS) due to the interaction of INZ with Ag NPs. Based on the linear increase in oxidation current, a sensitive INZ electrochemical sensor is constructed. The sensor displays a linear calibration range from 50.0 nM to 150.0 μM for INZ determination. Detection limit (based on three times standard deviation of the blank) and sensitivity of this sensor is 10.0 nM and 197 nA μM-1 cm-2, respectively. Further, P(MMA-co-AMPS) and Ag-P(MMA-co-AMPS) materials are successfully applied for analysis of INZ in presence of other biologically important molecules and also in a pharmaceutical formulation. The obtained results are very much consistent with the INZ amount originally present in the pharmaceutical formulation. © 2015 Elsevier Ltd. All rights reserved.
Emerging 3D nanomaterials as electrocatalysts for water splitting reactions
(Elsevier Ltd, 2024) Rohini Kumari; Aditi Sammi; Shubhangi; Ananya Srivastava; Uday Pratap Azad; Pranjal Chandra
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 LLC
Engineered Ni–Fe prussian blue analogue nanocubes and their transformation into nanocages and mixed oxide for applications as bifunctional electrocatalyst
(Elsevier Ltd, 2024) Shweta Pal; Subhajit Jana; Devesh Kumar Singh; Vellaichamy Ganesan; Uday Pratap Azad; Rajiv Prakash
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 LLC
Exploring the Potential Applications of Engineered Borophene in Nanobiosensing and Theranostics
(Multidisciplinary Digital Publishing Institute (MDPI), 2023) Ananya Srivastava; Daphika S. Dkhar; Nandita Singh; Uday Pratap Azad; Pranjal Chandra
A monolayer of boron known as borophene has emerged as a novel and fascinating two-dimensional (2D) material with exceptional features, such as anisotropic metallic behavior and supple mechanical and optical capabilities. The engineering of smart functionalized opto-electric 2D materials is essential to obtain biosensors or biodevices of desired performance. Borophene is one of the most emerging 2D materials, and owing to its excellent electroactive surface area, high electron transport, anisotropic behavior, controllable optical and electrochemical properties, ability to be deposited on thin films, and potential to create surface functionalities, it has recently become one of the sophisticated platforms. Despite the difficulty of production, borophene may be immobilized utilizing chemistries, be functionalized on a flexible substrate, and be controlled over electro-optical properties to create a highly sensitive biosensor system that could be used for point-of-care diagnostics. Its electrochemical properties can be tailored by using appropriate nanomaterials, redox mediators, conducting polymers, etc., which will be quite useful for the detection of biomolecules at even trace levels with a high sensitivity and less detection time. This will be quite helpful in developing biosensing devices with a very high sensitivity and with less response time. So, this review will be a crucial foundation as we have discussed the basic properties, synthesis, and potential applications of borophene in nanobiosensing, as well as therapeutic applications. © 2023 by the authors.
Fabrication of Advanced Nanohybrid Materials and Their Deployment in Electrochemical Sensing of Diverse Analytes
(Springer Science and Business Media B.V., 2024) Nandita Singh; Uday Pratap Azad; Ananya Srivastava; Rohini Kumari; Rajendra Prasad; Pranjal Chandra
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.
Facile synthesis of BSCF perovskite oxide as an efficient bifunctional oxygen electrocatalyst
(Elsevier Ltd, 2018) Uday Pratap Azad; Monika Singh; Sourav Ghosh; Ashish Kumar Singh; Vellaichamy Ganesan; Akhilesh Kumar Singh; Rajiv Prakash
We present a facile way to synthesize BSCF by using glycine-nitrate auto-combustion followed by annealing at different conditions, which work as high-performance bifunctional electrocatalyst for oxygen evolution (OER) as well as oxygen reduction (ORR) reactions in alkaline solution with comparatively better efficiency for OER. Annealing condition plays an important role towards catalytic performance due to morphological control and surface composition. Although, there is no significant change in onset potentials but these catalysts afford a current density >10 mA cm−2 at the potential of 1.65 V for oxygen evolution reaction and a current density >2.5 mA cm−2 at the potential of 0.009 V for oxygen reduction reaction with respect to RHE in 0.1 M KOH. The underlying mechanism for ORR and OER as well as catalytic activity differences were understood with the help of different analytical characterization techniques. © 2018 Hydrogen Energy Publications LLC
Hydrophobicity effects in iron polypyridyl complex electrocatalysis within Nafion thin-film electrodes
(Royal Society of Chemistry, 2016) Uday Pratap Azad; Dharmendra Kumar Yadav; Vellaichamy Ganesan; Frank Marken
Four polypyridyl redox catalysts Fe(bp)32+, Fe(ph)32+, Fe(dm)32+, and Fe(tm)32+ (with bp, ph, dm, and tm representing 2,2′-bipyridine, 1,10-phenanthroline, 4,4′-dimethyl-2,2′-bipyridine, and 3,4,7,8-tetramethyl-1,10-phenanthroline, respectively) are investigated for the electrocatalytic oxidation of three analytes (nitrite, arsenite, and isoniazid). The poly-pyridyl iron complex is exchanged into a Nafion film immobilized on a glassy carbon electrode, which is then immersed in 0.1 M Na2SO4. Cyclic voltammetry is employed for the evaluation of the mechanism and estimation of kinetic parameters. The electrocatalytic behaviour going from low to high substrate concentration is consistent with the Albery-Hillman cases of "LEty" switching to "LEk" (changing from the first order in the substrate to half order in the substrate), denoting a process that occurs in a reaction zone close to the electrode surface with diffusion of charge (from the electrode surface into the film) and of anionic or neutral analyte (from the Nafion-solution interface into the film). The relative hydrophobicity of the iron polypyridyl catalyst within the film is shown to affect both the diffusion of charge/electrons and analyte within the film with Fe(tm)32+ providing the mildest catalyst. All three analytes, nitrite, isoniazid, and arsenite, exhibit linear calibration ranges beneficial for analytical applications in the micro-molar to the milli-molar range. © 2016 the Owner Societies.
Influence of metal nanoparticles on the electrocatalytic oxidation of glucose by poly(NiIIteta) modified electrodes
(Wiley-VCH Verlag, 2010) Uday Pratap Azad; Vellaichamy Ganesan
Conductive polymeric [NiII(teta)]2+ (teta=C-meso-5,5,7,12,12,14-hexamethyl-1,4,8,11-tetra-azacyclotetradecane) films (poly(Ni)) have been deposited on the surface of glassy carbon (GC), Nafion (Nf) modified GC (GC/Nf) and Nf stabilized Ag and Au nanoparticles (NPs) modified GC (GC/Ag-Nf and GC/Au-Nf) electrodes. The cyclic voltammogram of the resulting electrodes, show a well defined redox peak due to oxidation and reduction of poly(Ni) system in 0.1 M NaOH. They show electrocatalytic activity towards the oxidation of glucose. AFM studies reveal the formation of poly(Ni) film on the modified electrodes. Presence of metal NPs increases electron transfer rate and electrocatalytic oxidation current by improving the communication within the Nf and poly(Ni) films. In the presence of metal NPs, 4 fold increase in current for glucose oxidation was observed. © 2010 Wiley-VCH Verlag GmbH&Co. KGaA, Weinheim.
Lanthanide based double perovskites: Bifunctional catalysts for oxygen evolution/reduction reactions
(Elsevier Ltd, 2021) Sachin Kumar; Monika Singh; Raj Pal; Uday Pratap Azad; Ashish Kumar Singh; Divya Pratap Singh; Vellaichamy Ganesan; Akhilesh Kumar Singh; Rajiv Prakash
In this work, we are reporting the facile synthesis of double perovskite oxide materials LnBa0.5Sr0·5Co1·5Fe0·5O6 (LnBSCF, Ln = Pr, Nd, Sm, and Gd) using citrate-nitrate based sol-gel method. These double perovskite oxide materials exhibit bifunctional catalytic activity for the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR). The phase formation and structure of the prepared oxides have been determined by powder X-ray diffraction, SEM analysis. Presence of various phases is analyzed and quantified by mean of Le-Bail refinement of XRD profiles. SEM analyses confirm the morphology and composition of prepared catalysts. Electrochemical measurements, e.g. Linear Sweep Voltammetry, Cyclic Voltammetry and Electrochemical Impedance spectroscopy were used to study catalytic performance of prepared catalyst towards both oxygen evolution and oxidation reduction reactions in alkaline solution. Better catalytic performance was obtained in case of double perovskites as compared to parent perovskite for both reactions. Best catalytic performance was observed for Gd based double perovskite. © 2021 Hydrogen Energy Publications LLC
Lanthanum-based double perovskite oxides as cobalt-free catalyst for bifunctional application in electrocatalytic oxygen reactions
(Elsevier Ltd, 2024) Divya Pratap Singh; Sanjukta Mukherjee; Sweta Bhagat; Nandita Singh; Monika Singh; Akhilesh Kumar Singh; Ashish Kumar Singh; Uday Pratap Azad; Suryabhan Singh; Lalrintluangi; Ved Prakash Singh
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 LLC
Modulation of catalytic activity of BSCF towards electrochemical oxygen reactions using different synthetic approaches
(Elsevier Ltd, 2024) Sweta Bhagat; Nandita Singh; Monika Singh; Ashish Kumar Singh; Suryabhan Singh; Uday Pratap Azad; Akhilesh Kumar Singh
This study is focused on the synthesis of the perovskite oxide materials, particularly Ba0.5Sr0.5Co0.8Fe0.2O3-δ, 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-δ 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-δ 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
Nanobioengineered surface comprising carbon based materials for advanced biosensing and biomedical application
(Elsevier B.V., 2023) Ananya Srivastava; Uday Pratap Azad
Carbon-based nanomaterials (CNMs) are at the cutting edge of materials science. Due to their distinctive architectures, substantial surface area, favourable biocompatibility, and reactivity to internal and/or external chemico-physical stimuli, carbon-based nanomaterials are becoming more and more significant in a wide range of applications. Numerous research has been conducted and still is going on to investigate the potential uses of carbon-based hybrid materials for diverse applications such as biosensing, bioimaging, smart drug delivery with the potential for theranostic or combinatorial therapies etc. This review is mainly focused on the classifications and synthesis of various types of CNMs and their electroanalytical application for development of efficient and ultra-sensitive electrochemical biosensors for the point of care diagnosis of fatal and severe diseases at their very initial stage. This review is mainly focused on the classification, synthesis and application of carbon-based material for biosensing applications. The integration of various types of CNMs with nanomaterials, enzymes, redox mediators and biomarkers have been used discussed in development of smart biosensing platform. We have also made an effort to discuss the future prospects for these CNMs in the biosensing area as well as the most recent advancements and applications which will be quite useful for the researchers working across the globe working specially in biosensors field. © 2023
Nanotechnology applications in pandemic prediction
(Elsevier, 2025) Nandita Singh; Kalyani Dewangan; Jitendra Sahu; Uday Pratap Azad; Divyanshu Singh; Sweta Bhagat; Ashish Kumar Singh; Suryabhan Singh; Sunil Kumar Singh; Ananya Srivastava; Divya Pratap Singh
The necessity for novel ways utilizing nanotechnology in antiviral tactics is demonstrated by the continuous fight against viral infections, which has been brought to light by the COVID-19 outbreak. With so many potential applications-biosensors, vaccines, disinfectants, and nanoparticles/functionalized nanoparticles have become increasingly attractive tool in the battle against viral epidemics. The function of nanoparticles in pandemic control is assessed in this book chapter, and their possible uses, advantages, and drawbacks are examined. The significance of nanotechnology in managing viral outbreaks, namely in vaccine development, is the first topic we cover. Although the use of metallic nanoparticles to functionalize protective face masks has become popular as a sustainable substitute for throwaway masks, improving virus filtering and cutting down on waste generation, incorrect disposal of these masks might pollute the environment and even cause ecological damage. In our second section, we will discuss various types of nanoparticles or functionalized nanoparticles-based sensors to detect the pandemic associated viruses at very early stage. For this purpose, along with various types of nanoparticle based-sensors, the selection of appropriate electrochemical techniques is also equally important for the better performance of the constructed biosensors. Along with COVID-19 we will discuss other pandemics such as swine flu, HIV/AIDS, and black death. We must reduce such possible dangers and environmental effects in order to properly control outbreaks. For this reason, it is essential to comprehend the benefits and drawbacks of using nanoparticles while creating efficient plans for controlling pandemics moving forward. © 2025 Elsevier Inc. All rights reserved.
Photochemical oxygen reduction by zinc phthalocyanine and silver/gold nanoparticle incorporated silica thin films
(2012) Manas Pal; Vellaichamy Ganesan; Uday Pratap Azad
Silver or gold nanoparticles are synthesized using a borohydride reduction method and are anchored simultaneously into/onto the mercaptopropyl functionalized silica. Later, zinc phthalocyanine is adsorbed onto the above materials. Thin films of these materials are prepared by coating an aqueous colloidal suspension of the respective material onto glass plates. Visible light irradiation of these films in oxygen saturated, stirred aqueous solutions effectively reduces oxygen to hydrogen peroxide. The photocatalytic reduction of oxygen is explained on the basis of the semiconducting properties of the silica films. The back electron transfer reaction is largely prevented by means of a sacrificial electron donor, triethanolamine. © 2012 Elsevier B.V.
Plant-based cellulose paper matrices for electro-optical sensing: Advances in fabrication and applications
(Elsevier B.V., 2025) Nandita Singh; Kalyani Dewangan; Ananya Srivastava; Uday Pratap Azad
Cellulosic paper, which is a sustainable and cost-effective material, has emerged as a fascinating material for effective electro/optical sensing device fabrication due to its unique physicochemical features, such as porosity, flexibility, and surface modifiability. The versatility, accessibility, affordability, and hydrophilic qualities of cellulose matrix make it an extremely appealing material for biosensor fabrication. Its surface properties can be easily molded or altered, and it possesses robust adsorptive properties for nanoparticles and biomolecules. This work presents the fabrication and application of a various cellulosic paper matrix engineered for use in integrated electrochemical and optical sensing systems. By functionalizing the cellulose fibers with appropriate conductive and photoreactive materials, enhanced sensitivity and selectivity toward various chemical and biological analytes can be easily achieved. The matrix supports both colorimetric and electronic signal transduction, enabling dual-mode detection capabilities suitable for sensitive and selective diagnostics, environmental monitoring, and wearable sensors fabrication. The review article explores the fabrication methods, sensor integration strategies, and performance metrics such as response time, limit of detection, and durability under diverse operating conditions. The latest developments in the production of cellulose-based sensors and their electroanalytical uses over the past 10 years have also been attempted to be covered. Most of the discussion centres around the development of cellulosic paper-based matrices and how they have been utilized in the fabrication of optical and electrochemical sensors. The results in this review article underscore the potential of cellulosic paper as a versatile and eco-friendly substrate for next-generation sensing technologies. © 2025 The Authors