Adsorption on nanoparticles with surface defects: mean field and energy level approaches

PASINETTI, P. M.; PENA-AUSAR, J. E.; PINTO, O. A.

PHYSICAL CHEMISTRY CHEMICAL PHYSICS

ROYAL SOC CHEMISTRY

Año: 2024

1463-9076

In this work two theoretical approximations, the so-called theoretical approach of energylevels and an extension of the modified mean field approach (TAEL and MMFA,respectively) are applied to the study of surface decoration of modified nanostructures likecrystalline nanoparticles. The surface of the nanoparticles is modified by the irreversiblerandom deposition of defects consisting in isolated atoms. Such deposition is carried out untila certain surface density is reached, leaving the rest of the sites available for a second speciesto adsorb. Through the formulation of the integral equation, the theoretical approaches permitobtaining the adsorption isotherms and the compressibility of the adlayer. The maindifference between the two approaches is the degree of details considered in theirmathematical formulations: TAEL takes in account all the energy levels meanwhile MMFAonly an average. The degree of precision and usefulness of both theories were evaluated incomparison with Monte Carlo simulations in the Grand Canonical assembly. Several caseswere studied: attractive and repulsive lateral interactions and different fraction of defects.The effects of the nanoscale were considered for different types and sizes of nanoparticles.By calculating an integral error, we are able to affirm that TAEL reproduces all the propertiesof the analyzed quantities from the reference simulated curves. On the other hand, the MMFAperformance is good only for a certain limited range of the parameters, however the strengthis in the mathematical simplicity compared to TAEL