Abstract
The search for new materials is closely linked to the development of synthesis techniques in solid state chemistry. Today, the diversity of these methods makes it possible to tackle a wide range of physico-chemical conditions. These range from high-temperature ceramics to low-temperature soft chemistry in water, from vapor-phase reactions to very high pressures. Nevertheless, many of these synthesis processes are energy-intensive and involve the use of large volumes of organic products, with a potentially high environmental impact. Drawing inspiration from nature therefore seems a fruitful approach to developing new synthesis methods. The search for alternative synthesis routes is also a means of exploring new reaction paths and hence new materials. This approach is well illustrated by the development of bioinspired materials. Other natural phenomena that do not directly involve the living world can serve as models. In particular, it is possible to draw inspiration from numerous geological processes, and thus develop a geoinspired chemistry of materials, applied to the development of varied ranges of materials, but also nanomaterials with diverse properties. The Earth thus appears as a formidable chemistry laboratory, offering a wide range of synthesis conditions.
After defining the framework of geoinspired chemistry for materials synthesis, we used a number of case studies to show how geological processes can be used to provide new synthesis routes, or modify existing ones : the aim was to provide solutions to specific questions in solid state and materials chemistry. We first tackled the problem of designing new metastable oxides, by coupling soft chemistry in water and the surface energy of nano-objects. We then showed how to use molten salts, inspired by ruby crystallogenesis conditions, for the selective synthesis of transition metal oxides as electrocatalysts for dioxygen reduction. We then discussed the use of molten salts for the elaboration of nanostructured non-oxide materials (borides, silicides), in particular for the electrocatalysis of water oxidation. In particular, we have shown how to couple the reactivity of molten salts and nanomaterials to develop new catalysts and compounds in general. Finally, we looked at high-pressure processes coupled with nanomaterials for the development of superhard materials.
