The growing need for energy by our society and the depletion of conventional energy sources demands the development and improvement of safe, renewable and low-cost clean energy technologies. Photovoltaic (PV) technology which makes use of the super-abundant and freely available Sun's energy to generate electricity has obvious economic, environmental and societal benefits. However, in order for PV technology to provide a significant fraction of the world's energy demands, devices must be composed of cheap and earth-abundant materials. Science and engineering are in a unique position to address the challenge to discover, design and develop inexpensive, non-toxic, and earth-abundant new materials that exhibit the ideal electronic properties for PV applications. This proposal outlines the strategy for the rational design of zinc phosphide (Zn3P2) heterojunctions for the efficient conversion of solar energy into electricity. Zinc phosphide is ideally positioned as a next-generation PV material due to its direct band gap of 1.50 eV, which allows it to absorb a high percentage of the solar spectrum. Zn3P2 also has a high visible-light absorption coefficient, long minority-carrier diffusion length, a large range of potential doping concentrations, and both of its constituent elements are non-toxic, cheap and abundant, which makes Zn3P2 a promising material for cost-effective and scalable thin-film photovoltaic applications. Despite its germane electronic properties, to date, a Zn3P2 device of sufficient efficiency for commercial applications has not been demonstrated. The highest solar energy-conversion efficiencies of 6.0% for multi-crystalline and 4.3% for thin-film cells have been reported. The low efficiencies of the thin film and heterojunction-based Zn3P2 devices have been attributed to poor understanding of the interfaces and band-alignment between the emitter and the absorber layers, to high concentrations of interface trap states (Fermi-level pinning), and/or to inadequate interface passivation. Given their 2-dimensional nature and their typical location buried within bulk materials, interfaces are difficult to resolve or access by purely experimental means. The goal of this cross-disciplinary project is, therefore, to develop and employ a combination of cutting-edge computational techniques and experiment to design and identify the key interfacial and electronic properties needed for the practical performance of zinc phosphide photovoltaics to achieve improved solar energy-conversion efficiencies. The use of a synergistic computational-experimental approach will help address key questions about the nature of atomic ordering (chemical and structural) and the electronic properties of the surface and interface of epitaxial Zn3P2 films grown on II-VI and III-V substrates, which will unlock a promising pathway towards the development and commercialization of low-cost, high-efficiency and earth-abundant Zn3P2 photovoltaic devices. The innovation of the proposed project is based on the engineering and transformation of earth-abundant and non-toxic Zn3P2 into a cost-effective, highly efficient and scalable thin-film PV material that provides additional environmental, health and economic benefits to the UK and globally. The main deliverables and benefits of the proposed project include, but are not limited to (i) atomic-level understanding of the surface and interface properties of a Zn3P2 epilayer, which has important implications on device fabrication and performance; and (ii) the growth of high-quality epitaxial Zn3P2 films on II-VI and III-V substrates as proto-types for industrial-scale PV applications.

The goal of this partnership is to create new catalysts for chemical reactions that are sustainable and help produce important chemicals and intermediates. Catalysts are essential substances that make chemical reactions happen more efficiently, and they are fundamental to many of the key processes that support our modern society. Without effective catalysts, many of the products and processes that we rely on would not be possible. At present, the chemical industry primarily uses fossil carbon sources like natural gas, oil, and coal. However, this approach is not sustainable in the long term, and it contributes to climate change and other environmental problems. As a result, researchers are looking for new ways to make chemicals that rely on green and sustainable carbon sources. Acetylene is one such molecule that has the potential to be an essential intermediate for a sustainable chemical industry. Acetylene chemistry was well developed over a century ago, but it was displaced as a central chemical intermediate by readily available ethene derived from oil. As a result, acetylene chemistry is currently an underexplored field. However, it is possible to produce acetylene from methane, which from biogas is a renewable source of carbon. Therefore, acetylene could become a crucial central intermediate for a new green chemical industry. We aim to design and understand catalysts based on Au, Pt, and AuPt that will act as a new class of catalysts to produce key chemicals and intermediates from acetylene. The partnership will bring together world-leading and complementary catalysis expertise, with the Cardiff Catalysis Institute (CCI collaborating with the UK Catalysis Hub (Harwell), the Max Planck Institute fur Kohlenforschung (KOFO, Mulheim), the Instituto de Tecnologia Quimica (ITQ), and the Fritz-Haber-Institute of the Max Planck Society (FHI, Berlin). A key benefit of this partnership is the additionality that it provides. By pooling expertise and resources, researchers can tackle grand challenge problems more effectively. The collaborative project brings together centres with unique and crucial expertise, such as the high-pressure facilities for acetylene catalysis at MPI KOFO, the fundamental surface science and advanced characterization techniques available at Harwell and FHI, the advanced computational methodologies of the FHI and the synthetic expertise concerning nanoparticles of ITQ. This partnership will enable UK researchers to access this expertise and cutting-edge facilities to tackle the complex challenge of making and characterizing new catalysts. The research will focus on gaining a fundamental understanding of what controls the activity of these catalysts in specific reactions, such as acetylene hydrochlorination and acetylene hydrogenation. Supported Au and Pt catalysts display a range of morphologies and often have individual atoms/cations, clusters, and nanoparticles. In some reactions, it is the well-dispersed Au+ cations that are active, while in others, nanoparticles are active. The research will seek to gain a deeper understanding of what controls the activity in these reactions and use this knowledge to design new and improved catalysts. To achieve these goals, we will use in situ/operando techniques and complementary capabilities available through the partnership to study these new catalysts. The team of experts assembled has worked together previously in various combinations, which will facilitate effective collaboration and communication. The ultimate goal of this partnership is to create new catalysts that will enable the sustainable production of important chemicals and intermediates, contributing to the development of a more sustainable and environmentally friendly chemical industry.

The chemical industry recognises the need to address the principles of sustainability and there is an urgent need to design processes as new paradigms in modern manufacturing residues or, if unavoidable, to recycle them. However, sustainability also requires the design of chemical processes that minimise the use of energy and direct the reaction towards the desired products, i.e. high selectivity at the required conversion with minimum energy consumption. Catalysis must be at the core of any new chemical process and the development of active, stable, and selective catalysts will be key for chemical sustainability. Most industrial chemical processes involve several chemical steps and each step often uses a different catalyst. Product separation and purification between each step also requires further equipment and energy consumption and hence it is highly beneficial to simplify the overall process. In this project, we aim to minimise the number of individual steps in chemical processes by tandem reactions with multifunctional heterogeneous catalytic systems that can perform the consecutive chemical reactions in one reaction, and we will achieve this using microchannel reactors. Moreover, we aim to achieve this for the preparation of key platform chemicals e.g. acetic acid is a major chemical intermediate that currently require several chemical process steps. The main objective of this project is to design and develop multifunctional catalysts combined with a microchannel structured reactor to convert methane into value-added oxygenate products including methanol and acetic acid via a tandem oxidative carbonylation process. The use of tandem heterogeneous catalysis represents an exceptionally novel approach to both catalyst and reaction design. We will explore the use of microchannel reactors for methane oxidation/carbonylation. Catalyst synthesis will be coupled with this reactivity testing and catalyst design will be driven by the reactor data. Catalysts will be characterised using state-of-the-art techniques. The engineering and science will operate in an iterative manner with each new step informing the overall programme. What will success look like? Success will be the demonstration of the potential of a bespoke combination of a microchannel reactor coupled with multifunctional catalysts, generating enhanced performance that could lead to a paradigm shift in the synthesis and application of catalytic tandem reactions.

The Cardiff Catalysis Institute, UK Catalysis Hub, Netherlands Centre for Multiscale Catalytic Energy Conversion (MCEC, Utrecht), and the Fritz-Haber-Institute of the Max Planck Society (FHI, Berlin) will use a novel theory-led approach to the design of new trimetallic nanoparticle catalysts. Supported metal nanoparticles have unique and fascinating physical and chemical properties that lead to wide ranging applications. A nanoparticle, by definition, has a diameter in the range one to one hundred nanometres. For such small structures, particularly towards the lower end of the size range, every atom can count as the properties of the nanoparticle can be changed upon the addition or removal of just a few atoms. Thus, properties of metal nanoparticles can be tuned by changing their size (number of atoms), morphology (shape) and composition (atom types and stoichiometry, i.e., including elemental metals, pure compounds, solid solutions, and metal alloys) as well as the choice of the support used as a carrier for the nanoparticle. The constituent atoms of a nanoparticle that are either part of, or are near the surface, can be exposed to light, electrons and X-rays for characterisation, and this is the region where reactions occur. Our lead application will be catalysis, which is a strategic worldwide industry of huge importance to the UK and global economy. Many catalysts comprise supported metal nanoparticles and this is now a rapidly growing field of catalysis. Metallic NPs already have widespread uses e.g., in improving hydrogen fuel cells and biomass reactors for energy generation, and in reducing harmful exhaust pollutants from automobile engines. Many traditional catalysts contain significant amounts of expensive precious metals, the use of which can be dramatically reduced by designing new multi-element nanocatalysts that can be tuned to improve catalytic activity, selectivity, and lifetime, and to reduce process and materials costs. A major global challenge in the field of nanocatalysis is to find a route to design and fabricate nanocatalysts in a rational, reproducible and robust way, thus making them more amenable for commercial applications. Currently, most supported metal nanocatalysts comprise one or at most two metals as alloys, but this project seeks to explore more complex structures using trimetallics as we now have proof-of-concept studies which show that the introduction of just a small amount of a third metal can markedly enhance catalytic performance. We aim to use theory to predict the structures and reactivities of multi-metallic NPs and to validate these numerical simulations by their synthesis and experimental characterisation (e.g., using electron microscopy and X-ray spectroscopy), particularly using in-situ methodologies and catalytic testing on a reaction of immense current importance; namely the hydrogenation of carbon dioxide to produce liquid transportation fuels. The programme is set out so that the experimental validation will provide feedback into the theoretical studies leading to the design of greatly improved catalysts. The use of theory to drive catalyst design is a novel feature of this proposal and we consider that theoretical methods are now sufficiently well developed and tested to be able to ensure theory-led catalyst design can be achieved. To achieve these ambitious aims, we have assembled a team of international experts to tackle this key area who have a track record of successful collaboration. The research centres in this proposal have complementary expertise that will allow for the study of a new class of complex heterogeneous catalysts, namely trimetallic alloys. The award of this Centre-to-Centre grant will place the UK at the forefront of international catalytic research.