Recently, there is an increasing interest in ammonia sensing and detection for a wide range of applications, including food, automotive, chemical, environmental, and medical sectors. A major challenge is to obtain selective, sensitive and environmentally stable sensing polymer/chemical materials that can meet the stringent performance requirements of these application areas. Among various polymer-based sensing materials, polyaniline has emerged as a preferred choice owing to its cost-effectiveness, facile preparation steps, and superior sensing performance towards ammonia. In this review, advances in polyaniline based ammonia detection sensors are summarized, with a special focus on progresses in polyaniline modification techniques to achieve enhanced sensing performance. These techniques utilize interfacial and high dilution syntheses, multifunctional dopants, template synthesis, self-oxidizing template synthesis, etc. , methods. Most up-to-date developments in combining polyaniline with other ammonia sensing materials, including polyaniline nanocomposites with metal oxides, graphene, carbon nanotubes and other carbon nanomaterials, are included. These novel nanocomposites have special capabilities of forming p - n nanojunctions or electron interphase interactions for superior detection sensitivity and selectivity. In addition, existing challenges toward understanding, reproducing, and optimizing the design of polyaniline based ammonia sensors are discussed.

A review on advances in application of polyaniline for ammonia detection

Engineering conducting polymer thin films with morphological homogeneity and long-range molecular ordering is intriguing to achieve high-performance organic electronics. Polyaniline (PANI) has attracted considerable interest due to its appealing electrical conductivity and diverse chemistry. However, the synthesis of large-area PANI thin film and the control of its crystallinity and thickness remain challenging because of the complex intermolecular interactions of aniline oligomers. Here we report a facile route combining air-water interface and surfactant monolayer as templates to synthesize crystalline quasi-two-dimensional (q2D) PANI with lateral size ~50 cm2 and tunable thickness (2.6–30 nm). The achieved q2D PANI exhibits anisotropic charge transport and a lateral conductivity up to 160 S cm−1 doped by hydrogen chloride (HCl). Moreover, the q2D PANI displays superior chemiresistive sensing toward ammonia (30 ppb), and volatile organic compounds (10 ppm). Our work highlights the q2D PANI as promising electroactive materials for thin-film organic electronics. Large area and homogeneous PANI thin films are important in high-performance organic electronics, but controlling the thickness and crystallinity in PANI thin films is challenging. Here the authors use air-water interface and surfactant monolayer templates to synthesize large area crystalline PANI films with tunable thickness.

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Engineering crystalline quasi-two-dimensional polyaniline thin film with enhanced electrical and chemiresistive sensing performances.

A chemoresistive ammonia sensor with sensitive polyaniline layer has been fabricated by gravure printing on flexible poly(ethylene terephthalate) substrate. Novel colloids of polyaniline hydrochloride, which were synthetized in xylene or chloroform in the presence of surfactant, were used as a printing formulation. The sensor characteristics of the colloid-based sensitive layers were compared with in-situ polymerized layers of polyaniline. The colloid-based sensors showed a good response to ammonia concentrations in the range from hundreds of ppb to tens of ppm. This provides an opportunity to use these sensors for both monitoring of maximum exposure limits for humans in workplaces as well as environmental air-pollution. Therefore, these fully printed, metal-free, low cost and flexible ammonia sensors based on organic materials can be used in detection systems for monitoring of hazardous gases.

Gravure-printed ammonia sensor based on organic polyaniline colloids

Custom designed metal anchored SnO2 sensor for H2 detection

Thiourea-treated graphene aerogel as a highly selective gas sensor for sensing of trace level of ammonia.

Dodecyl benzene sulfonic acid (DBSA) doped polyaniline (PANI) has been synthesized by ex-situ doping inemeraldine base (EB). The optical and functional properties of as synthesized DBSA doped PANI (PANI-DBSA) have been studied by UV-Visible and FTIR spectroscopy, respectively. A chemo-resistive gas sensorwas prepared using spin coated PANI-DBSA thin ﬁlm for quantitative detection of ammonia (NH 3 ) under ambi-ent conditions (27 C, 50% RH). The sensing characteristics of fabricated sensor were recorded using thedynamic resistance measurement, that revealed high sensitivity in relative response (∼4.5), response time(∼55 sec) and rapid recovery (∼100 sec). The PANI-DBSA thin ﬁlm sensor shows good linearity ( R =0.996)and repeatability over a wide concentration range of NH 3 from 5 to 250 ppm.KEYWORDS: Conducting Polymers, Polyaniline, Dodecyl Benzene Sulfonic Acid (DBSA), Ammonia. 1. INTRODUCTION Ammonia (NH 3 ) is widely used in the production of fer-tilizer, chemicals, refrigeration systems, medical diagno-sis system, material processing and its global productionexceeds from 100 million tons per annum. Its long-termexposure of about 8 hours and inhalation to higher con-centrations≥5000ppmcancauseserioushealthhazards.

Highly Sensitive Chemo-Resistive Ammonia Sensor Based on Dodecyl Benzene Sulfonic Acid Doped Polyaniline Thin Film

In this work, Fe3O4/graphene-oxide/chitosan aerogel (GCFA) with 3-D interconnected structure (average pore size ∼8.4 nm) and moderate BET surface area (∼59 m2/g) is synthesized by hydrothermal route. Three different hybrid symmetric supercapacitor cells are fabricated using GCFA as active electrode material, using basic (6M KOH: cell-1), acidic (1M H2SO4: cell-2), & neutral (Na2SO4: cell-3) as electrolyte mediums. Subsequently, a comprehensive study is carried out to assess the effect of electrolyte on the porous architecture, charge storage capacity, rate capability and cyclic stability. Besides, cell-3 also shows good cyclic stability with low initial fading (∼15%), good capacity retention (∼84%) It has been observed that cell-3 displayed better performance (specific capacitance ∼160 F g−1, specific energy∼14.6 Wh kg−1 and specific power∼0.77 kW kg−1) than either of cell-2 (∼160 F g−1, ∼7.84 Wh kg−1 and ∼0.45 kW kg−1) or cell-1 (∼102 F g−1, ∼1.54 Wh kg−1 and ∼0.14 kW kg−1) and excellent coulombic efficiency (∼91%) even after 10,000 charge-discharge cycles. This is attributed to the better pore accessibility, stability of residual surface functionalities under potential cycling, and least screening for intra-pore shuttling of counter-ions under neutral medium. 

Fe3O4/graphene-oxide/chitosan hybrid aerogel based high performance supercapacitor: effect of aqueous electrolytes on storage capacity & cell stability

Dodecyl benzene sulphonic acid (DBSA) doped polyaniline (PANI) nanorods have been synthesized by a templateless route via in-situ emulsion polymerization of aniline in aqueous DBSA solution. XRD patterns, UV-Visible Spectroscopy, and FTIR analysis confirm the formation of PANI and PANI-DBSA, whereas FESEM images revealed their elongated rod shaped morphology. The chloroform dispersion of synthesized PANI-DBSA was spin coated over prefabricated interdigitated Pt patterned glass substrate to realize porous gas sensing active layer. The sensor displays good response in 1–1200 ppm ammonia concentration range and can repeatedly detect 300 ppm of ammonia with response time of 6 s, recovery time of 37 s and relative response value of 9.57. Besides, its response was found to be linear for 1–50 ppm ammonia concentration with relative response per ppm value of 0.01675.

Improved Ammonia Sensing by Solution Processed Dodecyl Benzene Sulfonic Acid Doped Polyaniline Nanorod Networks

Recovery and analysis of polymeric layers from waste solar modules by chemical route

In this paper an attempt has been made to analyze the impact of global recession on financial performance of selected Indian automobile companies. For the purpose of analysis TATA Motors Limited & Maruti Suzuki India Limited the leading automobile companies of India have been taken into consideration. Secondary data have been collected through annual reports of selected companies and related websites. Further in the study the comparison of impact of recession on selected companies on the basis of Financial Performance have been analysed. Sample has been drawn by using convenient random sampling and statistical tools-ratios, paired t-test has been used. This study ends with findings and few suggestions.

Parveen Saini

Papers

Highly Sensitive Chemo-Resistive Ammonia Sensor Based on Dodecyl Benzene Sulfonic Acid Doped Polyaniline Thin Film

Fe3O4/graphene-oxide/chitosan hybrid aerogel based high performance supercapacitor: effect of aqueous electrolytes on storage capacity & cell stability

Improved Ammonia Sensing by Solution Processed Dodecyl Benzene Sulfonic Acid Doped Polyaniline Nanorod Networks

Recovery and analysis of polymeric layers from waste solar modules by chemical route

Impact of global recession in automobile industry (a comparative study of tata motors ltd. and maruti suzuki india ltd.)