Photocatalytic activity of multifunctional semiconductors: influence of morphology and electron injection

Abstract

Photocatalysts, traditionally semiconductors, are regarded as a promising technology for novel, powerful energy-storage systems, that are essential for processes ranging from water purification to water splitting, air filtration, and surgical instrument sterilization, and harvest optical energy to drive chemical reactions. The mechanism of energy storage in these materials is not fully understood yet because of the complex molecular mechanisms at the atomistic scale. Exploring the processes at the nanoscale provides necessary fundamental and thorough insights for improving the performance of such devices. To exam the photocatalytic activity in depth and to improve the materials for next-generation catalysts it is necessary a near-atomic resolution. The performance and key electronic properties of semiconductors are dictated by the interplay between the surface chemistry and morphology, whose manipulation has inspired experimental and theoretical researchers. Since most of the physical and chemical properties of the semiconductors are shape-dependent, the characterization and control not only of size but also of morphology of (nano) particles has a primary importance in nanoscience and nanotechnology. In this way, the study of the effect on the materials properties in function of the nanoparticles growth on the surfaces after the electron injection it is very important, once involves the changes of the corresponding physical and chemical properties related to structural order-disorder effects. In the last decades, molecular modeling has been established as a valuable technique for revealing fundamental insights into problems at the atomistic level. The theoretical studies not only capture the geometric and electronic effects on the photocatalytic activity but they are also capable to explain and rationalize the experimental data. In particular, the values of the surface energies obtained by first-principles calculations in combination with Wulff construction model provide structure-function relations based in depth atomistic modeling on morphological analysis, highlighting the importance of the theoretical chemistry in material science and nanotechnology. In this research project, we present a combined computational and experimental work, aimed to study the tungstates (BaWO4 e Ag2WO4) and molybdates (BaMoO4 e Ag2MoO4) by theoretical and experimental techniques. In the synthesis process, the main objective will be the control of morphology, particle size and structural organization. By using advanced first-principle calculations, we will be capable to analyze the electronic and structural properties of these tungstates and molybdates-based materials, at the bulk and the surface level. The expected results will be provide an understanding of the criteria warranting the existence, stability, and activity of a given configuration of atoms into the material that has pivotal relevance in chemical and materials science, as well as to find a correlation between the morphology/electron injection and the photocatalytic activity. (AU)