The reconstruction of Ni and Rh (001) surfaces upon Carbon, Nitrogen, or Oxygen adsorption

TL;DR

This study uses density-functional theory to analyze how carbon, nitrogen, and oxygen adsorption induce different surface reconstructions on Ni(001) and Rh(001), aligning with experimental observations and revealing the influence of chemical and steric factors.

Contribution

First-principles DFT calculations elucidate the mechanisms behind surface reconstructions of Ni(001) and Rh(001) upon adsorption of C, N, and O, explaining experimental patterns and variability.

Findings

Reconstruction patterns depend on adsorbate species and substrate.

Different reconstructions or lack thereof are explained by chemical and steric factors.

Results agree with experimental STM images and provide mechanistic insights.

Abstract

Nickel and Rhodium (001) surfaces display a similar - as from STM images - clock reconstruction when half a monolayer of C/Ni, N/Ni or O/Rh is adsorbed; no reconstruction is observed instead for O/Ni. Adsorbate atoms sit at the center of the black squares of a chess-board, $c(2\times 2)$, pattern and two different reconstructions are actually compatible with the observed STM images - showing a $(2\times 2)p4g$ pattern - according to whether a rotation of the black or white squares occurs. We report on a first - principles study of the structure of X/Ni(001) and X/Rh(001) surfaces (X=C,N,O) at half a monolayer coverage, performed using density-functional theory. Our findings are in agreement with all available experimental information and shed new light on the mechanisms responsible for the reconstructions. We show that the same substrate may display different reconstructions - or no reconstruction - upon adsorption of different atomic species, depending on the relative importance of the chemical and steric factors which determine the reconstruction.