Concerted progress in energy sources, sensing, and communications are bringing closer a future in which connected smart sensors will contribute to improved health and sustainable use of resources via environmental, personal health, and process monitoring. For maximum value, data should be generated and processed through means that are reliable, but also cost effective, energy efficient, and ecologically sound. By doing the initial conditioning and processing of incoming data close to the sensor (i.e. at the edge of a sensing network), energy savings and signal integrity can be improved, at the expense of local complexity. The electronic devices performing signal conditioning, data conversion, and decision in such systems are typically realised in state-of-the art and exorbitantly expensive chip manufacturing facilities (fabs). Recent pressure on the chip supply chain has increased the appeal of exploring alternative technologies. Chief among these are thin-film processes in which electronic devices and sensing components can be manufactured at a fraction of the cost, but simultaneously with: a major drop in performance; challenges in manufacturing circuits of the required complexity; and in many cases, much higher energy requirements during operation. At Surrey, we have devised and are developing a design philosophy and associated thin-film electronic device called the source-gated transistor (SGT), with superior power efficiency, stability, and amplification compared to conventional thin-film transistors, advantages which come at the cost of further reducing the operating speed. Our recent observation shows that the best SGT performance arises when combining thin semiconductor materials of high electrical permittivity with low-permittivity dielectrics, in a design that is counterintuitive to traditional approaches but is consistent with first principles. In this project, we will demonstrate SGTs and circuits, with hitherto inaccessible levels of performance and energy efficiency, by combining the advantages of the device architecture with the material properties of suspended crystalline silicon and germanium membranes. The charge carrier mobility of these materials, vastly superior to the usual thin films, and the geometrical scaling afforded by the exceptional SGT functional features, will enable circuits that are >100x faster and >10x more energy efficient than previous SGT-based designs. By expressly merging thin-film and "traditional silicon"-based approaches, these devices will serve as unique building blocks for highly efficient wearable, point-of-care, and distributed sensing systems with built-in sensing, signal conditioning, and decision. Even as we will be using materials aligned with traditional chips, our approach will not rely on the costly state-of-the art fabrication facilities, relieving much needed manufacturing capacity for complex chips e.g. processors and AI accelerators, while delivering transformative functionality to an emerging sensor ecosystem. In this initial project, the route to manufacturing will be explored, but as a secondary concern. We will focus primarily on the demonstration of a ground-breaking concept, through innovative joining of previously disparate materials and fabrication philosophies. In a high-risk, high-reward approach, we will confirm transistor operation, not only as amplifiers and signal conditioning stages, but potentially as sensors for bio-, chemical and mechanical stimuli. We will establish design rules and guidelines, supported by numerical simulation and by material and device characterisation. Thus, these advances will holistically represent a toolkit for the implementation of highly versatile, multipurpose sensing and processing systems towards a connected future beyond the Internet-of-Things. As a catalyst for prolific academic and industrial advances, the research will contribute firmly to maintaining the UK's leadership in emerging electronic technologies.

One of the greatest challenges of our time is to rapidly transition towards a low-carbon economy in order to limit the extent of climate change. The UK government's pledge to achieve net-zero emissions by 2050 will require decarburisation across all sectors, and thus the development of new technologies to ensure secure, reliable energy supplies are maintained. The expansion of solar and wind power has resulted in renewable energy costs that are competitive with or even undercut fossil fuel alternatives. However, further transition to renewable energy sources will require major changes in how we convert, store and use energy, including measures to deal with their intermittency and increased electrification. Electrochemical energy storage and conversion technologies will be central to this decarburisation effort, offering potential improvements in efficiency compared to current thermochemical processes (e.g. combustion). However, realising these efficiencies along with the performance needed for large-scale deployment requires the design of improved battery and electrocatalyst materials. This requires understanding of the nature of these materials and the reactions occurring on their surfaces during use. Although we can currently study these materials post-mortem, this tells us little about the reactions that occurred during their active life. This fellowship details a plan to develop and apply a suite of innovative characterisation techniques that will enable chemical reactions occurring at the buried interfaces in electrochemical devices to be directly observed during operation. By using windows that are transparent to X-rays, electrons and neutrons, the atomic-scale processes occurring on the surface of rechargeable battery electrodes and electrocatalysts for producing valuable chemicals will be revealed without disturbing the liquid environments in which they operate. This will enable the limitations of existing material combinations to be understood, and for new material solutions to be identified and tested. A unifying theme between the battery and electrocatalysis strands of this project will be a focus on concentrated electrolytes, in which the positively and negatively charged ions are no longer fully surrounded by a solvent (e.g. water). This is a promising strategy for supressing undesired reactions in order to extend battery life and improve electrocatalyst efficiency. It can also potentially reduce toxicity and improve safety in devices based on these electrolytes, which is highly desirable for their implementation at scale. The proposed approach will improve our understanding of how ions and solvents arrange at electrochemical interfaces in these concentrated solutions, and the resulting impact on the electrochemical reactions occurring. The understanding developed through this program of research is expected to inform the design of low-cost, safe battery systems suitable for grid-scale storage to buffer intermittent renewable energy sources. It will also contribute to the identification of improved electrocatalyst materials and processes for the production of carbon-neutral liquid fuels and chemicals. These advances will reduce our reliance on fossil fuel extraction, ultimately helping to tackle long-term challenges such as climate change.

Lord Kelvin famously stated "when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meagre and unsatisfactory kind". This holds none more true than for nanotechnology today. Emergent materials such as 2D transition metal dichalcogenide (TMD) compounds offer exciting, wide opportunities from novel (opto-) electronic devices to energy storage and catalytic energy conversion. For the latter, TMDs materials like MoS2 have shown high catalytic activity and offer large potential as earth abundant electro-catalysts to for instance convert waste CO2 into industrially relevant chemicals/fuels and to generate hydrogen sustainably, i.e. processes of utmost significance as strategies for a sustainable, clean future economy. However, TMD catalysts can undergo significant chemical and structural changes during reactions, and the mechanisms that give the high catalytic activity remain largely unknown. Our knowledge is currently equally meagre in terms of materials synthesis. There is very little understanding how TMDs actually grow and hence how the structure and properties of these materials can be scalably controlled. These challenges and lack of understanding are common to numerous emerging materials. One key reason for this is that they typically can only be resolved and adequately characterised at a "post-mortem" stage, and we are left to speculate what mechanisms actually govern growth or material functionality at industrially relevant "real-world" conditions. This proposal aims at true operando characterisation of novel materials like TMDs under industrially relevant reactive atmospheres at elevated temperatures, to have a transformative impact on their future use by developing a fundamental understanding of their design and functionality. Our focus will be on electron microscopy and spectroscopy, in particular scanning electron microscopy and X-ray photoelectron spectroscopy, which are among the most wide-spread and versatile characterisation techniques in modern science, used across all disciplines in academia and industry. They are endowed with high (near-)surface sensitivity, making them powerful tools for analysing the structure and chemistry of surfaces and interfaces. However, low-energy electrons are also strongly scattered by gas molecules, and therefore all these techniques are conventionally performed under high vacuum or restricted environmental conditions. We propose new environmental cell approaches that can be flexibly implemented for the many electron-based techniques to overcome these restrictions, and enable direct characterisation at high spatial and/or chemical resolution across an unprecedented range of industrially relevant process conditions for temperatures as high as 1000C and in reactive gaseous or liquid environments. The proposal builds on recent strategic equipment investment at Manchester, Cambridge and the Diamond Light Source/Harwell, and together with market-leading industrial partners our vision is to pioneer versatile approaches that open up new correlative, multi-modal operando probing capability applicable to a wide range of fields including organic semiconductors, battery/energy research, catalysis and life sciences. This will also link to simulation and theory to achieve new levels of understanding and predictive power. Applied to TMD materials, this capability will allow us to directly interrogate TMD nucleation and growth at industrially relevant reactor conditions, to develop new manufacturing processes including for so far largely unexplored metallic compounds. This will further allow us for the first time to systematically study model TMD catalysts under reaction conditions. In particular, we propose to explore metallic TMDs like NbS2, as unlike to semiconducting MoS2, their catalytic activity could extend over the entire basal plane, opening new directions to design novel electro-catalysts with low overpotential and high current densities.