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Functional Ion Conductance and Sensing

Final Report Summary - FUNICIS (Functional Ion Conductance and Sensing)

A wide range of interfacial physicochemical processes, from electrochemistry to the functioning of living cells involve spatially localized chemical fluxes that are associated with specific features of the interface. Scanning electrochemical probe microscopes (SEPMs) represent a powerful means of control, analysis and visualization of interfacial fluxes. This project, FUNICIS, aimed to expand the capabilities of SEPMs for functional imaging of technologically and fundamentally important interfaces. Progress in science is often related to technique development, and technological advances are of huge interest for researchers across many disciplines.
Research objectives of the project included: development of a novel approach for direct probing diffuse double layer structure at charged interfaces, characterization of individual metal nanoparticles, and reactivity mapping at the nanoscale using a new functional ion conductance imaging technique. The project also aimed at the training of the research Fellow, Dmitry Momotenko, and so the training objectives were set to: (i) learn and develop state-of-the art nanoscale electrochemical flux imaging techniques: (ii) develop an understanding of, and theoretical support for, novel imaging techniques through simulation methods, particularly for coupled mass transport – reactivity problems through the use of finite element method modeling and analytical theory: (iii) understanding of the structure-reactivity relationships at advanced materials for nanotechnology and catalytic applications; (iv) learning complimentary advanced imaging techniques, such as atomic force microscopy and transmission electron microscopy. Development of skills in supervision, presentation, teamwork, leadership and knowledge transfer were also included in the objectives list.
The project goals have been successfully achieved and the necessary work has been accomplished with high success. The project resulted in significant advances in capabilities of SEPMs. First of all, the new methodology of mapping, measuring and quantifying surface charge magnitudes has been developed and applied over a variety of samples. This work has started with a publication on mapping surface charges at interfaces of various materials and then, in the next work, a comprehensive simulation and experimental work has been performed for quantitative analysis of surface charge magnitudes. These findings have been further used for imaging and quantification of surface charges on complex biointerfaces, such as living cells under various conditions. An extensive way for characterization of geometrical and charge properties of nanopipette probes, required for better understanding of mass-transport in such nanoenvironments, as well as for analysis of technique capabilities. This has also resulted in a complete publishable work.
Second, the Fellow has made a major breakthrough in electrochemical imaging by establishing a novel approach for image acquisition, which allows the recording of high-quality maps of functional interfacial properties (e.g. reactivity) and demonstrated the capabilities of this advanced methodology on catalytic nanoparticles, modified surfaces and carbon materials (carbon nanotubes). This new imaging platform allowed the recording of image frames with a rate exceeding three orders of magnitude quicker than conventional methods! This methodology allowed the recording movies (rather than single images as previously) of chemical activity at interfaces and enabled a completely new level of measuring and understanding chemical activity of materials (including catalysts). Furthermore, this new approach has been implemented in the newly developed ion conductance technique for imaging interfacial reactivity, the operation of which is based on detection of local variations of ion conductance. The functional ion conductance imaging of reactivity is in many ways beneficial as compared to other SEPMs and has been successfully demonstrated for recording high-quality movies of chemical activity. Finally, the nanopipette method of spatiotemporal management of ionic fluxes have been applied for the fabrication and imaging of complex three-dimensional nanostructures by using dual-barrel nanopipette probes. Electrochemical control of ionic fluxes enables highly localized delivery of precursor species from one channel and simultaneous (dynamic and responsive) ion conductance probe-to-substrate distance feedback with the other for reliable high-quality patterning. This approach offers versatility and robustness for high resolution 3D “printing” (writing) and read-out at the nanoscale. Theoretical analysis and modelling have significantly contributed to a high success in these works. Comprehensive numerical simulation of the probe responses, mass transport and interfacial phenomena have been provided for understanding of the experimental observations and introduced a way of quantitative determination of important physicochemical characteristics of interfaces.
The Fellow has also demonstrated success in the training, teaching and knowledge transfer during the funding period. The Fellow has lead many research projects and in this role as a leader he developed and significantly improved his leadership, communication and teamwork skills. Throughout the project he mentored a group of postgraduate students (in total six) and also has taken part in teaching activities at the Department of Chemistry by teaching electrochemistry and surface science disciplines at undergraduate level. Dmitry has also closely worked with other postdoctoral researchers in the group and successfully published two reviews on the main topics of the project, including a chapter in a book on Nanoelectrochemistry published by CRC Press and an invited Feature article in ACS journal Langmuir.
The results of the project are of high interest to a broad community of researchers from different fundamental disciplines and applied sciences, spanning electronics, engineering, nano- and biotechnology and nanomedicine. The project has also hugely contributed to knowledge transfer between the Fellow and the Host Group, training and teaching of students at both undergraduate and postgraduate level. The Fellowship has also promoted further collaborations of the Group with industry and allowed establishing strong cross-disciplinary links with other researchers.