In pursuit of bifunctional catalytic activity in PdS2 pseudo-monolayer through reaction coordinate mapping

Abstract

We have investigated the photocatalytic efficiency and corresponding hydrogen and oxygen evolution reactions (HER and OER) through different functionalization of stable 1T palladium disulfide (PdS2) monolayer. The electronic structure calculations based on Density Functional Theory (DFT) formalism, have been performed along with the corresponding optical properties of functionalized and S-mono-vacancy defected 1T PdS2 monolayer. The optimum band gap required for water splitting makes this two-dimensional material an exciting promise for photocatalysis process. In this work, we have not only envisaged the photocatalytic activity, but also the specific reaction coordinates for HER and OER based on the adsorption energies of the intermediates of the individual reaction. Functionalization of 1T PdS2 monolayer is done by replacing the anion (S) site with P, N and C functionalized atoms and also by creating a mono-vacancy defect at the same site. We have also determined (i) the stability of the functionalized 1T PdS2 monolayer based on the phonon dispersion calculations and (ii) the respective work function of the individual systems. The steady optical response in the visible range is in favour of the photocatalytic activity of the monolayer, while the corresponding reaction coordinates predict the suitability of the functionalized and defected monolayer for HER and OER mechanism. The mono-vacancy defected and N-functionalized PdS⁠2 monolayer have emerged as the most promising systems for OER and HER activities respectively. Overall, we have predicted that the bifunctional catalytic activity can be achieved through functionalization and vacancy defect in PdS⁠2 monolayer.