Study of polyaniline-silver nanocomposite as humidity sensor

Study of polyaniline-silver nanocomposite as humidity sensor J. Bhadra, A. Popelka, N. J. Al-Thani, A. Abdulkareem Center for Advanced Materials, Qatar University, Qatar Abstract In this piece of work focus on fabrication of resistive type humidity sensor using polyaniline-silver nanocomposite (PPVA-Ag). Four different nanocomposites using four concentrations of silver (0.5,1.0, 1.5 and 2.0 M) and polyaniline (PANI) dispersed in polyvinyl alcohol matrix (PVA). PANI, and PVA concentrations are kept constant. Thin PPVA-Ag film on interdigited gold electrode fingers gives excellent sensitivity towards humidity at room temperature. 1. Introduction Since last few decades the information of nanoscience and nanotechnology has been explored extensively to obtain functionalized nanomaterials. One such category of nanomaterial is the polymer- metal nanocomposite, with enhanced mechanical, elastic, optical, electrical and dielectric properties [1]. Polymer nanocomposites are materials with nanosized one dimensional inorganic filler particles (around 10–100 ˚A), dispersed in an organic polymer matrix. An important parameter which has significant importance in many industries such as food, agricultural, clinical equipment and electronics is humidity, it is considered to be one of the most frequently measured physical parameters [2-3]. With the advancement in moisture sensitive technologies, research to achieve high efficient, low cost, reliable and miniature size of material sensitive to humidity change has gained acceleration. As among metal nanoparticles, Ag has high electrical and thermal conductivities, so the composite of Ag dispersed in PANI-PVA matrix gives rise to a functional materials, with improved antimicrobial activity and sensitivity towards humidity. This paper we focus on surface analysis of the thin film obtained using scanning electron microscopy and study on the humidity sensitivity. 2. Methods 2.1 Synthesis of Ag nanoparticles Four different concentrations of silver nitrate (AgNO3) is dispersed in aqueous PVA solution under constant stirring and heating at 60°C followed by photo reduction using UV-lamp having wavelength 390 nm for 24 hours. After exposing the above solutions with UV light for 24 hours, finally, yellowish-red colloid of Ag nanoparticles with average diameters of ∼30 nm and ∼70 nm uniformly dispersed in PVA are obtained. 2.2. Synthesis of PANI-Ag nanocomposite and pure PANI: The PANI-Ag nanocomposite blend is synthesized by in-situ chemical polymerization (Figure-1) of aniline monomer in the colloid solution obtained from section 2.1. During this process, aniline-DBSA is added to the Ag-PVA colloidal solution, followed by addition of the aqueous APS solution dropwise. The resulting blend mixture is left to react for 24 h under constant stirring at 5–10 °C. The colloidal solution obtained are used to prepare thin film on glass slide and interdigitated gold electrode washed with DI water and acetone and dried. Keeping the other concentrations and methods constant four different PPVA-Ag nanocomposites are prepared with 0.5, 1.0,1.5 and 2.0 M of AgNO3.qscienc

High School Students’ Perceptions of the Role of Social Support in Cultivating Their Interests in and Aspirations to STEM Degrees and Careers—A Middle Eastern Case Study

This case study intends to comprehend students’ perceptions of social support in cultivating their interests and aspirations for science, mathematics, engineering, and technology (STEM) degrees and careers. Survey-based quantitative research was employed, incorporating data from 1426 high school (grade 11th–12th) students in Qatar. The survey instrument encompassed four dimensions, i.e., (1) participants’ demographics, (2) STEM interests, (3) STEM supports/barriers and (4) STEM career aspirations to understand students’ perceptions. Spearman’s Rho correlation test demonstrated a positive correlation between students’ perceived social support (from family, teachers, and society) and their STEM interests (p < 0.01). Findings from the Mann-Whitney U test illustrated that females perceived enhanced social support (from teachers and society) in Qatar (p < 0.05). Even though teachers and society have been the stimulus to developing students’ STEM interests, there is still room to implement a policy for the consequential influence in constructing students’ STEM career aspirations. Thus, we believe these findings would urge policymakers to design tools that enable teachers and society to nurture, cultivate and sustain interest in STEM among the youth to meet Qatar’s National Vision 2030.The project was funded by Qatar University (Reference: QUCG-SESRI-20/21-1). The study was conducted according to the guidelines of the Declaration of Helsinki and approved by the Institutional Review Board of Qatar University (QU-IRB 1424-EA/20) on 1 March 2020

Promising transparent and flexible thermoelectric modules based on p-type CuI thin films—A review

The state-of-the-art thermoelectric technology owns a unique capability of direct, noise-free, and efficient conversion of waste heat into valuable electricity. The conventional thermoelectric generators are complex and expensive in fabrication, which restricts their use in wearable and miniaturized electronics to fulfill the current and rapid growth in demands for sufficient self-powered energy harvesters. Herein, this comprehensive review paper highlights the promising and next-generation thermoelectric generators based on flexible, transparent, abundant, non-toxic, and lightweight p-type Copper Iodide (CuI) thin films. It introduces the principles of energy conversion within thin-film thermoelectric generators and the structure of p–n junction including the criteria in the selection of substrates, p-type and n-type materials, connecting electrodes, and modules designed to sustain its mechanical flexibility and optical transparency. This review underlines the morphology and properties of CuI thin-film thermoelectric generators to figure out the latest trends in advanced synthesis and characterization techniques. It draws attention to its promising applications in wearable biosensing, energy harvesting, and smart miniaturized electronics. It discusses also the challenges and prospects in boosting the thermoelectric performance of CuI thin-film generators. This targeting to exceed the unity in its Figure-of-Merit (ZT) values for excellent output power generation, large-scale production for commercialization, and long-term stability for reliable thermoelectric applications.This work was supported by Qatar University Grant no. GTRA-17722. The statements made herein are solely the responsibility of the authors. Open Access funding is provided by the Qatar National Library. All authors have read and agreed to the published version of the manuscript

Long-Term Stability Analysis of 3D and 2D/3D Hybrid Perovskite Solar Cells Using Electrochemical Impedance Spectroscopy

Despite the remarkable progress in perovskite solar cells (PSCs), their instability and rapid degradation over time still restrict their commercialization. A 2D capping layer has been proved to overcome the stability issues; however, an in-depth understanding of the complex degradation processes over a prolonged time at PSC interfaces is crucial for improving their stability. In the current work, we investigated the stability of a triple cation 3D ([(FA0.83MA0.17)Cs0.05]Pb(I0.83Br0.17)3) and 2D/3D PSC fabricated by a layer-by-layer deposition technique (PEAI-based 2D layer over triple cation 3D perovskite) using a state-of-art characterization technique: electrochemical impedance spectroscopy (EIS). A long-term stability test over 24 months was performed on the 3D and 2D/3D PSCs with an initial PCE of 18.87% and 20.21%, respectively, to suggest a more practical scenario. The current-voltage (J-V) and EIS results showed degradation in both the solar cell types; however, a slower degradation rate was observed in 2D/3D PSCs. Finally, the quantitative analysis of the key EIS parameters affected by the degradation in 3D and 2D/3D PSCs were discussed.This publication was made possible by NPRP award [NPRP11S-1210-170080] from Qatar National Research Fund (a member of Qatar Foundation). The findings made herein are solely the responsibility of the authors

QUYSC STEM Digilearning Model

Covid-19 and the unprecedented shift in educational delivery, has revealed multiple perforations in the science-learning pedagogies. The technological replacements for a physical presence of an instructor and peer collaborated classroom could not retain student interaction and positive learning attitude as in the pre-Covid period. YSC STEM Digilearning Model, is an online voluntary summer course that was created to combat the respective hitches and was successfully implemented on 38 primary-preparatory students from diverse schools promising an active learning environment. Student Feedback mechanism approach was implemented throughout the course thereby providing voice to the students in the learner centered approach adopted by the STEM course. The course carried out diverse synchronous and asynchronous activities with positive student response as the study witnessed minimal student withdrawals and presentation of completed student assignments

Liquid exfoliated MoS2 sheet coupled with conductive polyaniline for gas sensor

Polyaniline (PANI)/MoS2 composites with porous microspheres were prepared by a hydrothermal and in situ polymerization method. The structural, optical, and morphological properties were characterized by X-ray powder diffraction, FTIR, scanning electron microscope, transmission electron microscope. The XRD results confirmed that the PANI/MoS2 composite was formed. Morphological characterization reveals that the successful formation of few to multilayered MoS2 nanosheet intercalated with the PANI nanoparticles

Do research experience programs promote capacity building in Qatar: Investigating the trend and participation differences

Research Experience programs (REPs) inspire students to pursue advanced degrees and shape their research career paths. Government and commercial organizations sponsor REPs to promote the capacity building of the country. In Qatar, the national youth is reported to show concerning participation in Science, Technology, Engineering, and Mathematics (STEM) disciplines at the K-12 level. However, none of the studies investigate these participation trends at the undergraduate level, especially in scientific research, which is deemed necessary for building a knowledge-based economy in Qatar. Therefore, to bridge this gap, the current study uses a quantitative approach to analyze the REP in Qatar through the participation data of 2455 undergraduate students. For this, statistical measures, including descriptive analysis, independent samples t-test, and Pearson's correlation analysis were used. Results indicated concerning trends in national student participation rate, implying underlying issues restricting their representation in undergraduate research activities. Also, statistically significant differences were found in student participation rates among students' gender and ethnic distributions. While female students demonstrated higher participation rates than males, national students showed lower participation than the non-nationals. Moreover, this low participation of national students suffered more drastically in STEM disciplines. Therefore, these findings determine the outlook for stakeholders and academic institutions in making meaningful educational decisions and envision synchronizing REPs at the university level, gauging measures to bolster the adjacent funding agencies and government organizations. Furthermore, being the first research addressing REPs in the Middle East region, this study has the potential to support educators in neighboring and other developing nations where STEM education is especially significant for human capacity building

Covid-19 inspired a stem-based virtual learning model for middle schools—a case study of Qatar

An unprecedented turn in educational pedagogies due to the COVID-19 pandemic has significantly affected the students’ learning process worldwide. This article describes developing a STEM-based online course during the schools’ closure in the COVID-19 epidemic to combat the virtual science classroom’s limitations that could promise an active STEM learning environment. This learning model of the online STEM-based course successfully developed and exercised on 38 primary–preparatory students helped them to overcome the decline in their learning productivity. Various digital learning resources, including PowerPoint presentations, videos, online simulations, interactive quizzes, and innovative games, were implemented as instructional tools to achieve the respective content objectives. A feedback mechanism methodology was executed to improve online instructional delivery and project learners’ role in a student-centered approach, thereby aiding in the course content’s qualitative assessment. The students’ learning behavior provided concrete insights into the program’s positive outcomes, witnessing minimal student withdrawals and maximum completed assignments. Conclusions had been drawn from the course assessment (by incorporating both synchronous and asynchronous means), student feedback, and SWOT analysis to evaluate the course’s effectiveness.We are deeply grateful to the office of Vice President for Research and Graduate Studies, Qatar University, for supporting the study. Moreover, we also thank Ras Laffan Industrial City-Community Outreach in supporting us for the effective implementation of the study

Synthesis and photoelectrochemical performance of Co doped SrTiO3 nanostructures photoanode

It is pertinent to realize that scientific research indicates that the most promising method for producing H2 is photo electrochemical water splitting through a photo anode. Cobalt-doped SrTiO3 (Co-SrTiO3) composite nanostructures were created in this study via hydrothermal synthesis. The impact of cobalt concentration change on Co-SrTiO3 has been identified using morphological, structural, and photo electrochemical research. Surface morphology of pure SrTiO3 nanoparticles using SEM and TEM reveals that the particles are intermittently agglomerated. The inclusion of Cobalt lowered the particle size of the nanostructures to 23 nm than pure SrTiO3 (41 nm). In addition, the peak profile has been influenced by cubic phase also identified from the x-ray diffraction analysis. The purity and composition of the materials were revealed by XPS analysis. The Co-SrTiO3 composite's produced the best charge transfer and recombination capabilities at 3% Co doping, according to electrochemical chemical impedance (EIS) spectroscopy. At 0.2 V applied potential, the obtained 3% Co-doped SrTiO3 photoanode system displays a photocurrent density of around 3.45 mA/cm2. The outcomes show that a promising application for the Co-doped SrTiO3 photoanode in photoelectrochemical water splitting.This publication was made possible by the support of an Qatar University Internal Grant (QUCG-CAM-20/21-6). The statements made herein are solely the responsibility of the authors. The characterizations of this work are accomplished in the Gas Processing Unit and in the Centra Laboratory Unit, at Qatar University

A distinctive method of online interactive learning in stem education

A breakthrough that has occurred in recent years is the emergence of the COVID-19 pandemic. It has affected various sectors of society, including the educational sector. It has prevented students from performing group-oriented hands-on activities and has eventually transformed their active learning environment in schools into virtual passive lectures at home. Therefore, to solve this impedance, we exercised several online STEM programs (five online STEM programs with repetitive cycles) for school students, including 140 students (middle and high school), 16 undergraduate (UG) secondary mentors, and 8 primary STEM professionals. Thus, the study revealed the results of a distinctive interactive online STEM teaching model that has been designed to overcome the virtual classroom’s impediments. The employed teaching model demonstrates an interactive learning environment that ensures students’ engagement, retention, and participation, driving them to STEM innovations. Various digital tools, including PowerPoint presentations, videos, online simulations, interactive quizzes, and innovative games were used as teaching aids. Both the synchronous and asynchronous means in a student-centered approach, along with the feedback mechanism, were implemented. Finally, the employed method’s effectiveness was revealed by the maximum student retention and STEM innovation rates, along with the model’s potentiality towards its replicability and sustainability. Thus, the outlook of such initiatives could further be broadened by its sustainability and replicability aspect towards vulnerable student communities such as academically introverted and specially challenged students