As previously mentioned, for periods 3-6 of groups 13-15, the adsorption is getting weaker as period number increases. This effect is most probably caused by rising covalent radii of the dopants with increase in atomic number. Higher-atomic-number elements, tend to engage in more vertical interaction with the Mo atoms, consequently reducing its availability for the adsorbate. Moreover, smaller variations in adsorption energy can be also observed among the investigated groups. In general, group 13 atoms facilitate the strongest adsorption. With three valence electrons, they readily adopt sp 2 hybridization, as seen in the AlCl 3 monomer. However, when adsorbed into the Te vacancy, this type of hybridization is not feasible, leading to the creation of a mixed sp 2 /sp 3 hybrids. These hybrid states are somewhat unfavorable given the valence configuration of the dopants, contributing to the observed weaker X-Mo bonding, as illustrated in Figure . Additionally, due to the absence of three electrons compared to Te, the dopant cannot facilitate the same number of electronic pairs, thereby reducing the oxidation level of neighboring Mo atoms. Consequently, doping MoTe 2 with group 13 elements makes subsequent adsorption highly favorable. In our case, the formation of a new vertical bond with the oxygen molecule signifies a substantial reduction in total energy, leading to a significant increase in chemical activity at the doping site. Group 14 dopants, having 4 valence electrons, tend to adopt sp 3 hybridization much easier than group 13 elements. For instance, sp 3 is adopted by Si in SiCl 4 , resulting in four single Si-Cl bonds. This in turn makes the non-flat bonding configuration more stable upon adsorption in the Te vacancy, resulting in the stronger X-Mo binding for group 14 dopants relative to group 13 (see Figure ). However, the electronic configuration in group 14 dopants (two less valence electrons than Te) makes it still insufficient to form all the electronic pairs as the Te does. This affects the bonding interaction, and causes changes in local charge distribution in the sheet. However, to a lesser extant than for group 13 dopants, resulting less enhanced chemical activity of the doping sites. Subsequently, group 15 atoms also create sp 3 hybridization, e.g., PCl 3 , and since they have only one valence electron less that Te, their impact on the adsorption strength is weaker that those facilitated by group 13 and 14 dopants, but still, notable stronger that the effects introduced by group 16 elements, where the same bonding interaction can be obtained as for Te. Finally, with 7 valence electrons, group 17, adds one more valence electron to the layer, in turn increasing the local chemical activity and adsorption strength relative to group 16 elements.