What is MASI? We believe that there is a strong link between the looming environmental crisis and the way we use chemical elements. In MASI, a multidisciplinary team of scientists from four UK universities (Nottingham, Cardiff, Cambridge, Birmingham), with 12 industrial and academic partners, is set to revolutionise the ways we use metals in a broad range of technologies, and to break our dependence on critically endangered elements. Simultaneously, MASI will make advances in: the reduction of carbon dioxide (CO2) emissions and its valorisation into useful chemicals; the production of 'green' ammonia (NH3) as an alternative zero-emission fuel and a new vector for hydrogen storage; and the provision of more sustainable fuel cells and electrolyser technologies. At the core of MASI is the fundamental science of metal nanoclusters (MNC), which goes beyond the traditional realm of nanoparticles towards the nanometre and sub-nanometre domain including single metal atoms (SMA). The overall goal of the MASI project is two-fold: (i) to provide a solution for a sustainable use of scarce metals of technological importance (e.g. Pt, Au, Pd), by maximising utilisation of every atom; and (ii) to unlock new properties that emerge in metals only at the atomic scale, allowing for the substitution of critical metals with abundant ones (e.g. Pt with Ni), and provide a platform for the next generation of materials for energy, catalysis and electronics applications. How does it work? We have recently developed the theoretical framework and instrumentation necessary to break bulk metals directly to metal atoms or nanoclusters, with their size, shape and composition precisely controlled. The atomic-scale control of nanocluster fabrication will open the door for programming their chemistry. For example, the electronic, catalytic or electrochemical properties of abundant metals, such as Ni and Co, may imitate endangered metals (Pt or Ru) at the nm and sub-nm scale, or by carefully controlled dispersion of the endangered elements with abundant ones in an alloy nanocluster. Our method allows direct deposition of metal atoms or nanoclusters onto solids (e.g. glass, polymer film, paper etc.), powders (e.g. silica, alumina, carbon etc.) and non-volatile liquids (e.g. oils, ionic liquids) in vacuum with no chemicals, solvents or surfactants and an accurately controlled metal loading. The directness of the MASI approach avoids generating chemical waste and enables a high 'atom economy', surpassing any wet chemistry methods. Moreover, surfaces of our metal nanoclusters are clean and highly active; additionally, being stabilised by interactions with the support material, they can be readily applied wherever electronic, optical or catalytic properties of metals are required. What is unique about these materials and our technology? MASI will offer greener, more sustainable methods of fabrication of metal nanoclusters, without solvents or chemicals, with the maximised active surface area ensuring efficient use of each metal atom. 'Naked', highly active metal surfaces are ready for reactions with molecules, activated by heat, light or electric potential, while tuneable interactions with support materials provide durability and reusability of metals in reactions. In particular, MASI materials will be suitable for the activation of hard-to-crack molecules (e.g. N2, H2 and CO2) in reactions that constitute the backbone of the chemical industry, such as the Haber-Bosch process. Similarly, highly dispersed metals and their intimate contact with the support material, will lead to high capacity for energy storage/conversion required in energy materials and fuel cells technologies. Importantly, MASI nanocluster fabrication technology is fully scalable to kilograms and tons of material, making it ideal for uptake in industrial schemes, potentially leading to a green industrial revolution.