ORCID Profile
0000-0001-7520-6458
Current Organisation
UNSW Sydney
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Publisher: The Electrochemical Society
Date: 05-2019
DOI: 10.1149/MA2019-01/44/2077
Abstract: This talk will focus on substrate-mediated nucleation and crystal growth of organic charge-transfer salt crystals and its application towards scalable manufacturing of nanowire sensors. Nanowires are widely recognized as the next generation building block for ultrasensitive and ultrafast chemical detection. Despite the research progress very few nanowire sensors have reached the market due to their manufacturing complexity. We are exploring a simple, low-cost electrocrystallization method to deposit nanowires from a solution droplet at room temperature directly on electronic substrates. We observed a phenomenon of 1-D crystal growth on nucleation seeds of small sizes. While the 1-D nanostructures resemble those produced by vapor-liquid-solid (VLS) or solution-liquid-solid (SLS) methods, their growth mechanisms are completely different. In our case, the small nanoparticle seed size (or radius of curvature) is responsible for the small size and 1-D growth of the organic crystals. We now apply the seed-mediated mechanism for the electrocrystallization of charge-transfer salt nanowires as small as 7 nm in diameter. The organic-based charge-transfer salt crystals are an underutilized class of sensor materials compared to carbon nanotubes (CNTs), conducting polymers, and metal oxides. We are also prototyping a gas sensor for ammonia detection by nanowire electrocrystallization on electrode patterns. Our approach significantly deviates from the current competing technologies, which involve complex, multistep fabrication and surface modification procedures. We have made nanowire sensors using different charge-transfer materials including tetrathiafulvalene charge-transfer salts and tetracyanoplatinate salts. We improve control of the nanowire deposition by applied potential, reactant concentration, and surface pattern. These nanowire materials show partial selectivity towards ammonia, ethanol, and other volatile organic compounds. We show further improvement in selectivity by the construction of a sensor array and machine learning to extra sensor data from the impedance spectra of more than one type of sensors.
Publisher: The Electrochemical Society
Date: 05-2020
DOI: 10.1149/MA2020-01302297MTGABS
Abstract: Major barriers for commercializing nanowire sensors are complicated synthesis technique and lack of scalable device assembly methods. Charge transfer salts (CTS), like tetrathiafulvalene bromide (TTFBr), have been well known for unique electric and chemical property. This talk will bring a controlled one-step deposition method to fabricate CTS nanowire sensors. By applying certain potentials to designed substrates, TTFBr nanowires can be directly deposited onto the electrodes. Varying deposition conditions and design of substrates are able to control the geometry, density and composition of TTFBr nanowires. TTFBr nanowire sensor shows high sensitivity, selectivity, and fast response towards ammonia gas. The detection limit is less than 1ppm and the response time, at room temperature, is less than 1 minute. Other CTS, like Cu- tetracyanoquinodimethane, can also be fabricated into nanowire sensor using the same method. This research shows a promising scalable fabrication method for various nanowire sensors and is being commercialized.
Publisher: Wiley
Date: 03-2023
Abstract: The lack of understanding for precise synthesis and assembly of nano‐entities remains a major challenge for nanofabrication. Electrocrystallization of a charge‐transfer complex (CTC), tetrathiafulvalene bromide (TTF)Br, is studied on micro/nanoelectrodes for precision deposition of functional materials. The study reveals new insights into the entire CTC electrocrystallization process from the initial nanocluster nucleation to the final elongated crystals with hollow ends grown from the working electrode to the neighboring receiving electrode. On microelectrodes, the number of nucleation sites is reduced to one by lowering the applied overpotential or precursor concentration. Certain current–time transients exhibit significant induction periods prior to stable nucleus growth. The induction regime contains small fluctuating current spikes consistent with stochastic formation of precritical nanoclusters with lifetimes of 0.1–30 s and sizes of 20–160 nm. Electrochemical analyses further reveal rate, size distribution, and formation/dissipation dynamics of the nanoclusters. Crystal growth of (TTF)Br is further studied on triangular nanoelectrode patterns with thickness of 5–500 nm, which shows a mass‐transfer‐controlled process applicable for precision deposition of functional (TTF)Br crystals. This study, for the first time, establishes CTC nanoelectrochemistry as a platform technology for precise deposition of conductive crystal assemblies spanning the source and drain electrode for sensing applications.
Publisher: Wiley
Date: 06-04-2023
Abstract: There is rapid growth in the global gas sensor market driven by new regulations for industrial emission control and residential environments and increasing demand for portable devices. Nanosensors promise to be the next generation gas sensors for the direct detection of chemical species due to their ultrahigh sensitivity, fast response, ultralow weight, and low power consumption. However, transitioning nanosensors from basic research or prototype projects to commercial products encounters two major technical challenges: difficulty in scale up and inability to demonstrate real‐world use in changing humidity and temperature conditions. The advances in addressing these two technical challenges in recent literature are surveyed. The most common 1D nanomaterials in R& D for gas sensing, metal oxides, and carbon nanotubes, as well as less common metal nanowires and psudo‐1D crystals made from charge‐transfer complexes (CTCs) are included. This review delves into the specifics of each of these 1D nanomaterials for gas sensing applications, their synthesis and deposition, sensing performance, and commercial development in the last 5 years. It highlights the scalability of one‐step electrodeposition of CTC nanowires on prefabricated electrodes, at room temperature, and from solution in making gas nanosensors.
Publisher: The Electrochemical Society
Date: 05-2020
DOI: 10.1149/MA2020-01522901MTGABS
Abstract: Ammonia is one of the largest produced chemicals with a global production of 150 million tons in 2017, expected to increase 8% in the next 4 years. It is widely used in several industries mainly in fertilizers manufacturing, but also in refrigeration systems, production of plastics, and as intermediates for pharmaceuticals synthesis. However, ammonia is highly corrosive and can damage cells in the body in contact, posing serious health risks. Despite the developments made in the detection systems, ammonia is still one of the most dangerous substances, responsible for the second highest number of chemical exposure casualties. The current detection solutions have serious limitations to be broadly used in industrial safety. Detection systems can generally fall under two categories, high-end equipment that is expensive, not user-friendly and can be only used in lab settings, and affordable devices that is prone to false alarms in a varying environment (humidity, temperature, etc.). In this presentation, we will talk about the Nanowire Organic Sensor technology as an alternative solution platform for ammonia monitoring that is affordable and can provide real-time and wide-area coverage. Our patented technology is a room-temperature process based on electrochemical deposition which facilitates scalable manufacturing directly on substrates and devices. Compared with the existing nanowire sensor fabrication methods, out innovation has four main unfair advantages. 1) By direct deposit of a solution droplet, nanowires are created right on chips or micro-fabricated devices. 2) It is a room temperature fabrication process, thus enabling less complex and capital-intensive manufacturing process. 3) It is a modular method that enables combinatory synthesis of a wide range of new organic nanowires. 4) It is a fabrication technology compatible with flexible electronics platforms. We will show how the combination of the sensor arrays, impedance spectroscopy and artificial neural networks model enhances the selectivity in varying levels of humidity. We will also talk about how the technology is compatible with the internet of things technology and cloud services, and how the combination could be leveraged to ensure more flexible monitoring of ammonia for industrial safety. Keywords: Electrochemical deposition, chemical sensing, nanomanufacturing.
Publisher: Informa UK Limited
Date: 29-08-2017
Publisher: The Electrochemical Society
Date: 02-2022
Abstract: Crystallization is at the heart of many industrial processes in pharmaceuticals, dyes and pigments, microelectronics, and emerging wearable sensors. This paper reviews nucleation and early-stage crystal growth activated by an electrical pulse at microelectrodes and nanoelectrodes. We review thermodynamic and kinetic theories of electrochemistry developed around microelectrodes. We describe various methods to make microelectrodes and nanoelectrodes. Fundamental understanding is still needed for predicting and controlling nucleation and early-stage crystal growth. Using nanoelectrodes, nucleation and growth kinetics can be studied on one nucleation site at a time. In contrast, on macroelectrodes, nanoparticles are nucleated at random sites and at different times. This gives rise to overlapping growth zones resulting in inhomogeneous particle deposition and growth. The random size and density distributions prevent electrodeposition from being widely adopted as a manufacturing tool for making nanodevices. We describe advances in electrodeposition of metal nanoparticles and organic charge-transfer complexes on micro/nanoelectrodes. We anticipate increased interests in applying electrochemistry for making nanodevices particularly nanosensors and nanosensor arrays. These electrochemically fabricated nanosensor arrays will in turn fulfill the promise of nanoelectrodes as the most advanced analytical tools for medical diagnostics, environmental monitoring, and renewable energy.
Publisher: Royal Society of Chemistry (RSC)
Date: 2009
DOI: 10.1039/D3NA00507K
Publisher: Springer Science and Business Media LLC
Date: 12-08-2021
DOI: 10.1038/S41467-021-25192-4
Abstract: Atmospheric NO 2 is of great concern due to its adverse effects on human health and the environment, motivating research on NO 2 detection and remediation. Existing low-cost room-temperature NO 2 sensors often suffer from low sensitivity at the ppb level or long recovery times, reflecting the trade-off between sensor response and recovery time. Here, we report an atomically dispersed metal ion strategy to address it. We discover that bimetallic PbCdSe quantum dot (QD) gels containing atomically dispersed Pb ionic sites achieve the optimal combination of strong sensor response and fast recovery, leading to a high-performance room-temperature p-type semiconductor NO 2 sensor as characterized by a combination of ultra–low limit of detection, high sensitivity and stability, fast response and recovery. With the help of theoretical calculations, we reveal the high performance of the PbCdSe QD gel arises from the unique tuning effects of Pb ionic sites on NO 2 binding at their neighboring Cd sites.
Publisher: Wiley
Date: 28-06-2018
DOI: 10.1002/CAE.21940
Publisher: Wiley
Date: 02-09-2020
Publisher: The Electrochemical Society
Date: 2019
DOI: 10.1149/2.1001902JES
No related grants have been discovered for Mohamed Kilani.