Namonics Laboratory, Department of Physics, Gauhati University

Dr. Abha Chhabra, Scientist/Engineer- SG, Space Applications Centre (SAC), ISRO, Ahmedabad and other Delegates from ISRO visited Namonics Lab during their visit to the Regional Academic Centre for Space (RAC-S) at Gauhati University, Assam and really appreciated the works that are going on in the lab.

Congratulations to Dr. Rajesh Ghosh as you stand as the very first PhD graduate from our lab! This milestone is a testament to your unwavering dedication, relentless hard work, and incredible patience throughout this journey. Achieving this prestigious degree is no small feat.

Your success marks a proud moment for all of us, inspiring your peers and setting a high standard for future researchers. May this achievement open doors to exciting opportunities and pave the way for continued excellence in your academic and professional pursuits. We are honored to have been part of your journey and look forward to witnessing your future contributions to the field. Warmest congratulations once again!

We are very pleased to inform that our research work titled, "Selective and Sensitive Detection of Ammonia at Room Temperature by the WS2-PANI Nanocomposite on a Flexible Paper-Based Sensor with Cost-Effective Chemically Expanded Graphite Ink Electrodes" has been published in one of the most reputed journals ACS journals under Applied electronic materials. Here, a facile way of synthesizing WS2 nanosheets in an aqueous solvent and fabrication of interdigitated electrodes (IDEs) on a flexible substrate using chemically expanded graphite (CEG) conductive ink has been reported in this study. The synthesized WS2 nanosheets have been utilized for highly sensitive and selective flexible ammonia (NH3) sensors at room temperature by incorporating polyaniline (PANI) with the nanosheets, following a cost-effective route. The IDEs have been fabricated on a flexible photopaper substrate using a cost-effective spray coating method. The resistance of the fabricated IDEs is comparable to standard gold and copper electrodes. The flexible sensor shows enhanced sensing performance, with higher response, high selectivity, prolonged stability, and a low detection limit of 3 ppm experimentally (≈9 ppb, theoretically). The effect of the relative humidity level has also been investigated. The response and recovery times for 5 ppm of NH3 v***r are found to be 38 and 58 s, respectively. The sensor shows remarkable recovery after returning from the bending condition to the relaxed (normal) position. The experimental results agree with the density functional theory (DFT) analysis that has been performed to support the experimental results. The electronic charge density differences of the WS2-PANI nanocomposite in the proximity of NH3 show significant variation compared to other interfering volatile organic compounds (VOCs). In addition, the sensing mechanism of the WS2-PANI nanocomposite toward NH3 has also been discussed.
We congratulate the authors, Anurag Kashyap, Hrishikesh Sarma, Bipradip Chakraborty, and Hemen Kalita.

Selective and Sensitive Detection of Ammonia at Room Temperature by the WS2-PANI Nanocomposite on a Flexible Paper-Based Sensor with Cost-Effective Chemically Expanded Graphite Ink Electrodes A facile way of synthesizing WS2 nanosheets in an aqueous solvent and fabrication of interdigitated electrodes (IDEs) on a flexible substrate using chemically expanded graphite (CEG) conductive ink has been reported in this study. The synthesized WS2 nanosheets have been utilized for highly sensitiv...

We are pleased to announce that our research work titled "Tunable Sensitivity In Graphene-based Soil Moisture Sensors Via Controlled V***r Phase Reduction Method" has been published in the IEEE journal under IEEE Sensors Letters. Here, a resistive-reduced graphene oxide (RGO) based sensor is developed using chemical v***r reduction. This resistive sensor has a good sensitivity to soil moisture. The RGO is synthesized by v***r phase reduction of graphene oxide (GO) using hydrazine hydrated as a reducing agent at room temperature. The controlled reduction of GO is achieved by varying the exposure time of it to the hydrazine hydrate v***r. The sensing results indicate the p-type sensing nature of the fabricated RGO sensor. The RGO sensor shows ∼ 5.68% and 121% sensor response for 2% and 15% soil moisture content respectively. The decrement of sensor response is observed with the increment of reduction time. This signifies the tunable sensitivity of our fabricated sensor via controlled v***r phase reduction by varying its reduction parameter. The scope for developing RGO-based soil moisture sensors in the agricultural sector is less explored till now.

We would like to congratulate the authors Biswajit Dehingia, Rajnandan Lahkar, Biswajit Dey and Hemen Kalita.

Tunable Sensitivity In Graphene-based Soil Moisture Sensors Via Controlled V***r Phase Reduction Method In this report, a resistive-reduced graphene oxide (RGO) based sensor is developed using chemical v***r reduction. This resistive sensor has a good sensitivity to soil moisture. The RGO is synthesized by v***r phase reduction of graphene oxide (GO) using hydrazine hydrated as a reducing agent at roo...

We are happy to announce that one of our book chapters titled "Flexible and Wearable Chemical Sensor Based on Graphene Derivatives" has been published by Springer in the book "Nanoscale Matter and Principles for Sensing and Labeling Applications".

Congratulations to the authors Hemen Kalita, Anurag Kashyap, Rajesh Ghosh, and Biswajit Dehingia.

Flexible and Wearable Chemical Sensor Based on Graphene Derivatives Flexible and wearable sensors have attained tremendous attention in the last few years due to their rising demand for real-time monitoring. Starting from monitoring human health to the surrounding environment, wearable sensors have drawn the attention of researchers...

Congratulations to the authors....

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We are delighted to announce that our research work titled "Efficient removal of both cationic and anionic dyes from water using a single rGO/PSS nanocomposite membrane with superior permeability and high aqueous stability" has been published in Elsevier Journal under Journal of Environmental Chemical Engineering (IF= 7.7). Here, a rGO/PSS composite is used for the fabrication of the a rGP membrane using a simple vacuum filtration method. The fabricated membrane has excellent water permeability ∼ 600 Lm−2h−1bar−1 along with high aqueous stability and recyclability. The fabricated single membrane can remove both cationic (MB) and anionic (MO) dyes with a removal efficiency of more than 99% and 96% respectively. Antifouling properties of the membrane are also investigated, which shows 57% of fouling recovery ratio while using higher concentration of fouling reagent (SA). The excellent water permeability, high removal efficiency, significant aqueous stability in both acidic and basic medium, and good antifouling behavior are promising for its practical application in harsh environmental conditions.

We congratulate the authors Biswajit Dehingia, Rajnandan Lahkar and Dr. Hemen Kalita.

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One week workshop on Analytical Instruments and Material Characterization organised by SAIF, Gauhati University, sponsored by DST-PURSE, Gauhati University. The registration link and the event details can be found in the brochure. https://instgu.com/index.php/saif

Website for details.

Anurag Kashyap Rajnandan Lahkar Hrishikesh Sarma

We are glad to announce that a patent has been granted to two of our lab members namely, Rajesh Ghosh and Anurag Kashyap, and our group leader Dr. Hemen Kalita for an invention entitled "A facile method of heating method of preparation of vertically oriented graphene oxide nanosheets".

Congratulations to Rajesh Ghosh, Anurag Kashyap, and Dr. Hemen Kalita.

We are delighted to inform you all that our research work titled "Fabrication of highly conductive graphene paper for supercapacitors with a one-step hydrothermal method" has been published in Elsevier publication under Carbon Trends. Here, we present a facile one-step hydrothermal method for the fabrication of free-standing graphene paper using aqueous graphene oxide (GO) dispersion as the starting material. Notably, the method does not require the use of any additives for the reduction and preparation of the graphene paper. The resulting graphene paper exhibits a high degree of reduction, as confirmed by X-ray photoelectron spectroscopy (XPS) analysis, revealing a carbon-to-oxygen (C/O) ratio of ∼7. The fabricated graphene paper also demonstrates excellent conductivity, with a measured value of ∼1900 S/m, and sheet resistance of around 100 Ω/sq. Furthermore, the energy storage capability of the graphene paper-based electrode is evaluated, which shows a promising specific capacity of 249 F/g at a current density of 1 A/g in 1M H2SO4 as the ionic medium. Additionally, the electrode has also demonstrated remarkable energy density and power density values of 28.68 Wh/Kg and 455 W/Kg, respectively. Overall, the resulting graphene paper exhibits high conductivity and excellent electrochemical performance, making it a promising candidate for various energy storage applications.

We congratulate Rajesh Ghosh and Dr. Hemen Kalita.

Fabrication of highly conductive graphene paper for supercapacitors with a one-step hydrothermal method We present a facile one-step hydrothermal method for the fabrication of free-standing graphene paper using aqueous graphene oxide (GO) dispersion as t…

We are very pleased to inform you that one of our group members, Mr. Rajesh Ghosh, and our Group leader, Dr. Hemen Kalita, have filed one more Patent. Congratulations to Rajesh Ghosh and Dr. Hemen Kalita.

We are very pleased to inform that our research work titled "Selective and Sensitive Detection of Formaldehyde at Room Temperature by Tin Oxide Nanoparticles/Reduced Graphene Oxide Composite" has been published in ACS publication under Applied Nano Materials (Impact factor: 6.140). In this article, a highly selective formaldehyde (HCHO) gas sensor using a tin oxide nanoparticles–reduced graphene oxide (rGO–SnO2) composite has been fabricated and investigated for room-temperature sensing. The rGO–SnO2 composite is synthesized by cost-effective wet chemical method. The fabricated sensor exhibits remarkable sensing performance, including a higher response, a low detection limit of ≈33 ppb (theoretical), good selectivity, and long-term stability. Furthermore, the effects of humidity level and calcination temperature have also been investigated. The response and recovery times for 10 ppm HCHO v***r are found to be 35 and 10 s, respectively. The promising results in the lab-scale HCHO detection with pre-treated fish opens up avenues for the non-invasive detection of HCHO in food adulteration. The density functional theory study is in good agreement with the experimental results. The electronic charge density differences of the rGO–SnO2 composite in the proximity of HCHO show significant variation. In addition, the sensing mechanism of the rGO–SnO2 composite toward HCHO has also been discussed.
We congratulate Anurag Kashyap and Dr. Hemen Kalita.

Selective and Sensitive Detection of Formaldehyde at Room Temperature by Tin Oxide Nanoparticles/Reduced Graphene Oxide Composite A highly selective formaldehyde (HCHO) gas sensor using a tin oxide nanoparticles–reduced graphene oxide (rGO–SnO2) composite has been fabricated and investigated for room-temperature sensing. The rGO–SnO2 composite is synthesized by cost-effective wet chemical method. The fabricated sensor ex...