Density functional theory investigation of As4, As2 and AsH3 adsorption on Ti-doped graphene

Abstract Arsenic species (As4, As2 and AsH3) released during the coal gasification process can cause significant damage to human health and the environment. In this work, the adsorption capability of Ti-doped graphene for As4, As2 and AsH3 was investigated through density functional theory calculations. The optimized adsorption configuration, adsorption energy and electronic structure were analyzed in detail. The results showed that a single vacancy graphene-based substrate with three nitrogen atoms doping (Ti/SV-N3) was a promising adsorbent for the simultaneous removal of arsenic species, but the adsorption behavior of As4, As2 and AsH3 were different. The adsorption of As4 on Ti/SV-N3 belonged to the dissociation model, and its adsorption process was dominated by both electron transfer and orbital hybridization. As2 and AsH3 were adsorbed on the substrate surface in the form of molecules. In the adsorption systems of As2 on Ti/SV-N3, ionic and covalent bonds were both formed, similar to As4. For AsH3 adsorbing on the substrate, the adsorption systems of Ti/GS all exhibited weak chemisorption, which was mainly controlled by ionic interactions. In addition, instead of the d-band center, the relationship between the adsorption activity and the electronic structure can be explained by the partial d-band center, especially for the adsorption system of As2 on Ti/GS. Furthermore, the Fermi softness can be used to describe the adsorption activity of Ti/GS.