Vishal Chaudhary

Bio: Vishal Chaudhary is an academic researcher from University of Delhi. The author has contributed to research in topics: Materials science & Medicine. The author has an hindex of 7, co-authored 14 publications receiving 151 citations.

Enhanced room temperature sulfur dioxide sensing behaviour of in situ polymerized polyaniline–tungsten oxide nanocomposite possessing honeycomb morphology

Abstract: A polyaniline–tungsten oxide hybrid nanocomposite with honeycomb type morphology was synthesized by in situ one pot chemical oxidative method and used for sulfur dioxide (SO2) monitoring application for the first time. Using a cost-effective spin coating technique a sensing device was fabricated for the monitoring of SO2 at levels as low as 5 ppm. The fabricated sensing device works at room temperature, which reduces its power consumption, cost and need for complex circuitry. It was found that the sensing response of the nanocomposite based sensing device (∼10.6%) is greatly enhanced as compared to that of its individual parent devices (∼4% for polyaniline nanofibres and is negligible for tungsten oxide nanostructures) for 10 ppm SO2 at room temperature. The reason for this remarkable response has been discussed in light of several factors, such as optimum porosity, branched structure and formation of heterojunctions. In addition, the fabricated nanocomposite based sensor was found to be reliable in terms of stability, selectivity, response and recovery time, detection range and reproducibility. The mechanism of SO2 sensing in the said composite is proposed and discussed in terms of the formation of heterojunctions and explained with an appropriate energy band diagram.

Emergence of MXene–Polymer Hybrid Nanocomposites as High‐Performance Next‐Generation Chemiresistors for Efficient Air Quality Monitoring

Abstract: Air contamination is one of the foremost concerns of environmentalists worldwide, which has elevated global public health concerns for monitoring air contaminants and implementing appropriate safety policies. These facts have generated nascent global demand for exploring sustainable and translational strategies required to engineer affordable, intelligent, and miniaturized sensors because commercially available sensors lack lower detection limits, room temperature operation, and poor selectivity. The state‐of‐the‐art sensors are concerned with architecting advanced nanomaterials to achieve desired sensing performance. Recent studies demonstrate that neither pristine metal carbides/nitrides (MXenes) nor polymers (P) can address these practical challenges. However, synergistic combinations of various precursors as hybrid‐nanocomposites (MXP‐HNCs) have emerged as superior sensing materials to develop next‐generation intelligent environmental, industrial, and biomedical sensors. The expected outcomes could be manipulative due to optimizing physicochemical and morphological attributes like tunable interlayer‐distance, optimum porosity, enlarged effective surface area, rich surface functionalities, mechanical flexibility, and tunable conductivity. This review intends to detail a comprehensive summary of the advancements in state‐of‐the‐art MXP‐HNCs chemiresistors. Moreover, the underlying sensing phenomenon, chemiresistor architecture, and their monitoring performance are highlighted. Besides, an overview of challenges, potential solutions, and prospects of MXP‐HNCs as next‐generation intelligent field‐deployable sensors with the integration of IoT and AI are outlined.

Advancements in research and development to combat COVID-19 using nanotechnology

Abstract: The whole world is currently facing a global health crisis due to the coronavirus disease (COVID-19) pandemic caused by SARS coronavirus 2, which started in Wuhan City, China, in December 2019. The pandemic has affected 235 countries, areas or territories and infected over 42 million people across the globe as per WHO update on 27 October 2020. More than 1.1 million people have died and the numbers are increasing daily. However, some drugs have been authorized for emergency treatment of patients, medication and vaccines with proven efficacy to prevent and treat the disease is still under various phases of development. The entire world is consistently making efforts to address three major challenges related to COVID-19 including prevention of its spread, prompt and early diagnosis and treatment of patients to save lives. Touted as one of the game-changing technologies of the century, nanotechnology has huge potential to develop solutions against these three major challenges of the disease. Nanotechnology comprises of multidisciplinary prospects encompassing diverse disciplines including medicine, material science, artificial intelligence, environment, virology, physical sciences, chemistry and biology. The numerous challenges can be addressed through the engineering of the various physicochemical properties of materials presents in abundance in nature. Various claims, studies and reports on research and development to combat these challenges associated with COVID-19 have been collectively discussed in this article from the perspectives of nanotechnology.

Room-temperature SO2 gas-sensing properties based on a metal-doped MoS2 nanoflower: an experimental and density functional theory investigation

Abstract: This paper demonstrates a sulfur dioxide (SO2) gas sensor based on a transition-metal-doped molybdenum disulfide (MoS2) nanocomposite synthesized via a facile single-step hydrothermal route. The Ni-doped, Fe-doped, Co-doped, and pristine MoS2 film sensors were fabricated on a FR4 epoxy substrate with interdigital electrodes. The morphologies, microstructures, and compositions of as-prepared samples were fully examined using X-ray diffraction, energy dispersive spectroscopy, scanning electron microscopy, transmission electron microscope, and X-ray photoelectron spectroscopy. The gas-sensing properties of the four samples were systematically investigated at room temperature, and the Ni-doped MoS2 film sensor was screened out as the optimal SO2 sensor among the four sensors, exhibiting a relatively high response value, quick response/recovery time, and excellent stability toward SO2 gas. Furthermore, in order to explain the experimental results, we used Materials Studio software to construct molecular models of adsorption systems and calculate the geometry, energy, and charge parameters via density functional theory (DFT) based on first principles. The sensing mechanism is also discussed in depth. Through a comprehensive research approach of combining experimentation with DFT simulation, this work suggests that an Ni-doped MoS2 film sensor is able to detect SO2 gas at room temperature.

Recent Advances in Electrochemical Sensors for Detecting Toxic Gases: NO₂, SO₂ and H₂S.

Abstract: Toxic gases, such as NOx, SOx, H2S and other S-containing gases, cause numerous harmful effects on human health even at very low gas concentrations. Reliable detection of various gases in low concentration is mandatory in the fields such as industrial plants, environmental monitoring, air quality assurance, automotive technologies and so on. In this paper, the recent advances in electrochemical sensors for toxic gas detections were reviewed and summarized with a focus on NO2, SO2 and H2S gas sensors. The recent progress of the detection of each of these toxic gases was categorized by the highly explored sensing materials over the past few decades. The important sensing performance parameters like sensitivity/response, response and recovery times at certain gas concentration and operating temperature for different sensor materials and structures have been summarized and tabulated to provide a thorough performance comparison. A novel metric, sensitivity per ppm/response time ratio has been calculated for each sensor in order to compare the overall sensing performance on the same reference. It is found that hybrid materials-based sensors exhibit the highest average ratio for NO2 gas sensing, whereas GaN and metal-oxide based sensors possess the highest ratio for SO2 and H2S gas sensing, respectively. Recently, significant research efforts have been made exploring new sensor materials, such as graphene and its derivatives, transition metal dichalcogenides (TMDs), GaN, metal-metal oxide nanostructures, solid electrolytes and organic materials to detect the above-mentioned toxic gases. In addition, the contemporary progress in SO2 gas sensors based on zeolite and paper and H2S gas sensors based on colorimetric and metal-organic framework (MOF) structures have also been reviewed. Finally, this work reviewed the recent first principle studies on the interaction between gas molecules and novel promising materials like arsenene, borophene, blue phosphorene, GeSe monolayer and germanene. The goal is to understand the surface interaction mechanism.

Highly sensitive and selective SO2 MOF sensor: the integration of MFM-300 MOF as a sensitive layer on a capacitive interdigitated electrode

Abstract: We report on the fabrication of an advanced chemical capacitive sensor for the detection of sulfur dioxide (SO2) at room temperature. The sensing layer based on an indium metal–organic framework (MOF), namely MFM-300, is coated solvothermally on a functionalized capacitive interdigitated electrode. The fabricated sensor exhibits significant detection sensitivity to SO2 at concentrations down to 75 ppb, with the lower detection limit estimated to be around 5 ppb. The MFM-300 MOF sensor demonstrates highly desirable detection selectivity towards SO2vs. CH4, CO2, NO2 and H2, as well as an outstanding SO2 sensing stability.

Vanadium doped tin dioxide as a novel sulfur dioxide sensor (vol 75, pg 385, 2008)

Abstract: Considering the short-term exposure limit of SO2 to be 5 ppm, we first time report that semiconductor sensors based on vanadium doped SnO2 can be used for SO2 leak detection because of their good sensitivity towards SO2 at concentrations down to 5 ppm. Such sensors are quite selective in presence of other gases like carbon monoxide, methane and butane. The high sensitivity of vanadium doped tin dioxide towards SO2 may be understood by considering the oxidation of sulfur dioxide to sulfur trioxide on SnO2 surface through redox cycles of vanadium-sulfur-oxygen adsorbed species.