Interest of Gas Phase Processes for the Synthesis of Materials Activated under Light: Example in Photocatalysis and Photovoltaics

International audienceDue to its high activity under near UV illumination, one of the most studied materials in photocatalytic as well as in photovoltaic studies is titanium dioxide TiO$_2$ especially in its anatase crystalline form. In both cases, one of the phenomena limiting the efficiency is the recombination of electron-holes pair. In this context, the use of composites based on TiO$_2$ nanoparticles and carbon or metallic nano-objects is a relevant strategy towards more efficient electron transfer processes. This paper will present the one-step synthesis of such nanocomposites and some studies on their photocatalytic or photovoltaic applications. To achieve the synthesis of high quality nanocomposites presenting well-controlled physical properties, we use the laser pyrolysis method. This method is based on the interaction between a high power CO2 laser and a gaseous or liquid precursor. In all cases Titanium tetraisopropoxide (TTIP) was used as the TiO$_2$ precursor. Hydrogen tetrachloroaurate was dissolved in the TTIP solution to produce Au loaded TiO$_2$ nanoparticles (Figure 1, left). The efficiency of these nanoparticles was studied under air and N$_2$ for the photocatalytic decomposition of acetic acid. Graphene nanoparticles were dispersed in liquid TTIP to produce composite nanoparticles where TiO$_2$ is grown at the surface of the graphene layers (Figure 1, right). These composite nanoparticles were used to form the porous layer of a perovskite solar cell. In both cases, a significant effect is observed by comparison to the performances obtained from pure TiO$_2