Explicit solvation effects on low-index Fe surfaces and small particles as adsorbents of Arsenic species: A DFT study

Density functional theory (DFT) calculations were carried out on hydroxylated and solvated (H&S) Fe substrates. Fe (110) and (111) extended surfaces as well as clusters of 32 and 59 atoms, and a nanoparticle of 80 atoms were studied as adsorbent substrates of harmful As species. Arsenious (H3AsO3) and arsenic (H3AsO4) acids are physisorbed on the H&S Fe(110) but chemisorbed on the H&S Fe(111) surface. The open-packed plane of the (111) surface, with free active sites, allows better interaction with the acid molecules. The small hydroxylated cluster, Fe32, has shown the best activity as adsorbent of H3AsO3. Electronic charge transfer occurs not only from Fe atoms that directly interact with the acid molecule, but neighbouring Fe atoms are also oxidized. This work presents clear evidence that these spherical Fe aggregates, formed mainly by (111) faces and with an important percentage of low-coordination sites, are excellent adsorbent substrates of H3AsO3 and should be considered as a reference to search for new supported catalysts. Fil: Alfonso Tobón, Leslie Lissette. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Física del Sur. Universidad Nacional del Sur. Departamento de Física. Instituto de Física del Sur; Argentina Fil: Branda, María Eva. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Física Aplicada "Dr. Jorge Andrés Zgrablich". Universidad Nacional de San Luis. Facultad de Ciencias Físico Matemáticas y Naturales. Instituto de Física Aplicada "Dr. Jorge Andrés Zgrablich"; Argentina