Molecule-decorated rutile-type ZnF2(110): A periodic DFT study

摘要

Weak binding of small molecules onto surfaces is a powerful tool whereby interfacial phenomena are studied in atomistic level. It is well-recognized that physisorption is a precursor to chemisorption and the subsequent heterogeneous catalysis. Although at least in part overlooked, vdW-driven sorption of particles on rutile-like substrates is of potential value due to the wide variety of the applications it serves. Probing the acidity of rutile-structured adsorbents by means of molecular adsorption is the quintessential case of long-range-dominated adsorption on such materials. Monomer, half-layer and monolayer physisorption of gaseous CO and N-2 at (110) facet of rutile-like ZnF2 was investigated through dispersion free and dispersion-corrected DFT. The PBE and optB88-vdW calculated stretching frequencies for freestanding and adsorbed CO and N-2 were in excellent agreement with their experimentally observed counterparts, when available. Traditional vdW-DF, its successor, vdW-DF2, and RPBE-D3 predict surface energies that match well with B3LYP result. As well, outstanding consistency was found between the vdW-DF and vdW-DF2 computed binding energies and their highly accurate LMP2 equivalent. Whilst being computationally far more efficient, vdW-DF and vdW-DF2 attained interaction energies were closer to the LMP2 benchmark data than the previously reported B3LYP adsorption energy.