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Item Ammonia sensing via pseudo molecular doping in uv-activated ambipolar silicon nanowire transistors(ACS American Chemical Society, 2025) Vardhan, Vaishali; Biswas, Subhajit; Tsetseris, Leonidas; Ghosh, Sayantan; Echresh, Ahmad; Hellebust, Stig; Huebner, Rene; Georgiev, Yordan M.; Holmes, Justin D.; Horizon 2020The potential of adsorbed gaseous molecules to create shallow electronic states for thermally excited charge carrier transport and to engineer silicon transistor properties has been largely overlooked compared to traditional substitutional impurities. This paper successfully modifies the electrical properties of ambipolar silicon junctionless nanowire transistors (Si-JNTs) using the reducing properties of ammonia (NH3) for selective detection. Physisorption of NH3 induces a dual response in both p- and n-type conduction channels of ambipolar Si-JNTs, significantly altering current and key parameters, including the “on” current (Ion), threshold voltage (Vth), and mobility (μ). NH3 interaction increases conduction in the n-channel and decreases it in the p-channel, acting as an electron donor and hole trap, as supported by Density Functional Theory (DFT) calculations. This provides a pathway for charge transfer and ″pseudo″ molecular doping in ambipolar Si-JNTs. This NH3-mediated molecular doping and conduction modulation in Si transistor enabled, for the first time, the electrical detection of gaseous NH3 at room temperature across a wide concentration range (200 ppb to 50 ppm), achieving high sensitivity (200 ppb) and precise selectivity under ultraviolet (UV) light. UV illumination dynamically modulates current and reveals distinct sensing features in the p- and n-channels of the dual-responsive Si-JNTs. The ambipolar Si-JNT sensor exhibits a fast response time of 1.91 min for 0.8 ppm of NH3 in the hole conduction channel and a high sensitivity of 80% for 0.8 ppm of NH3 in the electron conduction channel. This dual-channel approach optimizes sensor performance by leveraging the most responsive parameters from each channel. Furthermore, the ambipolarity of Si-JNTs broadens the parameter space for developing a multivariate calibration model, enhancing the selectivity of Si-JNT sensors for NH3 detection.Item Promoting air quality-related awareness and behavioural change: a rapid review of communication interventions integrating behavioural, science communication and socio-ecological perspectives(Elsevier, 2025-07-23) Cibin, Roberto; Horgan, Laura; Ciolfi, Luigina; Dockray, Samantha; Murphy, Gillian; Venables, Dean S.; Cassarino, Marica; Science Foundation IrelandAir pollution (AP) is a global environmental threat to human health and development. Day-to-day behaviours contribute to poor air quality (AQ) but limited public understanding of AQ warrants effective communication strategies to promote awareness and empower positive behavioural change. Through the integration of behavioural, science communication, and socio-ecological frameworks, this rapid review maps existing AQ-related communication interventions and their influence on AQ awareness, protective and/or mitigating behaviours (i.e., avoiding exposure; reducing polluting activities), and civic engagement. We conducted a comprehensive literature search of peer-reviewed and grey literature, including 79 studies for analysis. Findings were synthesised narratively and assessed for quality with the QuADS tool. Despite high heterogeneity in intervention types, most served a persuasion or enablement function, often utilising dissemination modes such as websites or web applications, and most assessed awareness and/or engagement in protective behaviours. While most interventions focused on individual/household-level actions and interindividual dynamics, only some considered policy-level actions, and very few embedded infrastructural considerations in their communication. Overall, 47 studies reported positive impacts on awareness and/or behaviours, particularly through participatory approaches, although we noted issues associated with promoting meaningful participation and identified influencing psychosocial factors. Evidence of effectiveness for behaviours was often limited by observational designs and the focus on awareness only or self-reported behaviours/intentions. Our findings highlight growing attempts to communicate AQ-related risks and behavioural solutions through empowering approaches that are sensitive to individual and local circumstances, but note the need for further work to foster mitigating behaviours and civic engagement.Item Heterogeneous Fenton-type oxidative degradation of low-density polyethylene to valuable acid products using a nanostructured Fe–CeO2 solid solution catalyst(Royal Society of Chemistry, 2025-01-02) Breen, Rachel; Holmes, Justin D.; Collins, Gillian; Science Foundation IrelandThe chemical conversion of waste plastic polymers to useful commodity chemicals has become crucial to helping tackle the issue of global plastic waste today. Polyolefins maintain the highest production rate and lowest recycling rate worldwide due to their inert chemical structures. This work shows the synthesis of solid-solution Fe–CeO2 catalyst as an excellent heterogeneous catalyst for Fenton-type oxidative degradation of low-density polyethylene to achieve high yields of organic acids. The catalyst was synthesized in 3 molar ratios of Fe : Ce and it was found that the molar ratio of iron and cerium was crucial for catalytic performance with the Fe–CeO2 1 : 1 catalyst giving the highest yields of acid products. The catalyst achieved 91% mass loss and 71% organic acid at pH 7, with 1 wt% catalyst loading. The use of a multi-metal Fenton system resulted in a synergistic effect, displaying superior activity to systems with only one Fenton active metal. The heterogeneous nature of the catalyst allowed for easy recovery and demonstrated excellent recyclability in multiple cycles. The high recyclability performance was attributed to the stability of the solid solution structure.Item Pseudo molecular doping and ambipolarity tuning in Si junctionless nanowire transistors using gaseous nitrogen dioxide(John Wiley & Sons, Inc., 2024-11-19) Vardhan, Vaishali; Biswas, Subhajit; Ghosh, Sayantan; Tsetseris, Leonidas; Ghoshal, Tandra; Hellebust, Stig; Georgiev, Yordan M.; Holmes, Justin D.; Horizon 2020Ambipolar transistors facilitate concurrent transport of both positive (holes) and negative (electrons) charge carriers in the semiconducting channel. Effective manipulation of conduction symmetry and electrical characteristics in ambipolar silicon junctionless nanowire transistors (Si-JNTs) is demonstrated using gaseous nitrogen dioxide (NO2). This involves a dual reaction in both p- and n-type conduction, resulting in a significant decrease in the current in n-conduction mode and an increase in the p-conduction mode upon NO2 exposure. Various Si-JNT parameters, including “on”-current (Ion), threshold voltage (Vth), and mobility (µ) exhibit dynamic changes in both the p- and n-conduction modes of the ambipolar transistor upon interaction with NO2 (concentration between 2.5 – 50 ppm). Additionally, NO2 exposure to Si-JNTs with different surface morphologies, that is, unpassivated Si-JNTs with a native oxide or with a thermally grown oxide (10 nm), show distinct influences on Ion, Vth, and µ, highlighting the effect of surface oxide on NO2-mediated charge transfer. Interaction with NO2 alters the carrier concentration in the JNT channel, with NO2 acting as an electron acceptor and inducing holes, as supported by Density Functional Theory (DFT) calculations, providing a pathway for charge transfer and “pseudo” molecular doping in ambipolar Si-JNTs.Item Exfoliated molybdenum disulfide nanosheet networks as sensing materials for nitrogen dioxide detection(American Chemical Society, 2025-01-24) Urs, Kusuma; Carey, Tian; Tsetseris, Leonidas; Liu, Shixin; Synnatschke, Kevin; Sofer, Zdeněk; Coleman, Jonathan N.; Wenger, John Charles; Biswas, Subhajit; Holmes, Justin D.; Horizon 2020; European Commission; Deutsche Forschungs Gemeinschaft; Europen Research Council; European Regional Development FundNitrogen dioxide (NO2) is a gaseous air pollutant linked to respiratory and cardiovascular diseases and environmental problems such as acid rain and tropospheric ozone formation. Reference instruments for measuring NO2 are expensive, highlighting the need to develop low cost sensor technologies for wider scale monitoring of this critical pollutant. Here, we report the development of a scalable sensor using electrochemically exfoliated 2D molybdenum disulfide (MoS2) networks. The sensor can detect a wide range of NO2 concentrations at room temperature, with an experimental limit of detection (LOD) as low as 150 ppb and a theoretical LOD of 1.9 parts per quadrillion (ppq) in dry air. The sensor exhibited approximately 90% response to 1 ppm of NO2 within 10 min of exposure. UV irradiation significantly enhanced the sensor’s recovery time, reducing it from 20 min to less than 2 min. Evaluation of the sensor within a large (∼6.5 m3) atmospheric simulation chamber yielded a similar response and recovery time performance, opening the opportunity for further tests in the chamber under various conditions. Finally, using Density Functional Theory (DFT) calculations, we identified key atomic-scale structures and processes highlighting the importance of electrochemically exfoliated sulfur-deficient MoS2 for sensitive room temperature NO2 detection.