The combined demands of increasing energy production and the need to reduce fossil fuels to limit global warming have paved the way for an urgent need for clean energy harvesting technologies. One interesting solution is to use solar energy to produce fuels. Thus, low-cost materials such as semiconductors have been intensively studied for photocatalytic reactions. Among them, 1D nanostructures hold promise due to their interesting properties (high specific and accessible surfaces, confined environments, better charge separation). Imogolite, a natural hollow nanotube clay belongs to this category. Although it is not directly photoactive in the visible light range (high band gap), it exhibits a permanent wall polarization due to its intrinsic curvature. This property makes it a potentially useful co-photocatalyst for charge separation. Moreover, this nanotube belongs to a family sharing the same local structure with different curved morphologies (nanosphere and nanotile). In addition, several modifications of these materials are possible (wall doping with metals, coupling with metal nanoparticles, functionalization of the internal cavity) allowing tuning band gap. The proof of concept (i.e., photocatalytic nanoreactor) was only obtained for the nanotube form.

This phD project aims to study the whole family (nanotube, nanosphere, and nanotile, with various functionalizations) as nanoreactors for reduction reactions of protons and CO2 triggered under irradiation.