Pure and M-doped (M=Zn, Cu, Ni, Co) cadmium oxide nanosheets, novel adsorbents for the adsorption of ethyl benzene and ortho, meta, para xylene: a theoretical study

The electronic and structural properties investigation of pure and zinc, copper, nickel, cobalt doped cadmium oxide nanosheets (CdONS) and the adsorption of ethyl benzene (EB) and ortho- meta- para xylene (OX, MX, PX) on these nanosheets were studied by density functional theory calculations. The adsorption energy, charge transfer, energy gap, spatial distribution of HOMO and LUMO orbitals and electron density scheme of ethyl benzene and ortho, meta, para xylene molecules on pure and doped CdONS are calculated. The obtained results show that the adsorption energy value increases after doping Zn, Cu, Ni and Co atoms in oxygen substituted state, especially in Ni_OCdONS and Co_OCdONS. The adsorption energy of EB, OX, MX and PX on Ni_OCdONS and Co_OCdONS is about − 260 kJ/mol whereas its value on pure CdONS is approximately − 100 kJ/mol. In comparison with pure CdONS, the adsorption energy of the molecules on M_CdCdONS, decreases except in Ni_CdCdONS. The adsorption energy of OX, MX and PX on Ni_CdCdONS is − 263.12, − 150.94 and − 151.85 kJ/mol, respectively. Also, the results show that the value of energy gap increases after the adsorption of EB, OX, MX and PX on Co_OCdONS, therefore, Co_OCdONS can be proposed as proper adsorbent and sensor for these molecules.