Suppression of Surfaces States at Cubic Perovskite (001) Surfaces by CO${_2}$ Adsorption

TL;DR

This study uses first-principles calculations to show that CO₂ adsorption on cubic ABO₃ perovskite surfaces suppresses surface states and modulates band gaps, highlighting potential for CO₂ sensing applications.

Contribution

It provides detailed insights into how CO₂ adsorption affects surface states and band gaps of various cubic ABO₃ perovskites, identifying promising materials for chemiresistive CO₂ sensors.

Findings

CO₂ forms stable CO₃-like complexes on surfaces.

Surface states are suppressed, increasing band gaps to bulk levels.

TiO₂-terminated SrTiO₃ and BaTiO₃ are promising for sensors.

Abstract

By using first-principles approach, the interaction of CO${_2}$ with (001) surfaces of six cubic ABO${_3}$ perovskites (A = Ba, Sr and B = Ti, Zr, Hf) is studied in detail. We show that CO${_2}$ adsorption results in the formation of highly stable CO${_3}$-like complexes with similar geometries for all investigated compounds. This reaction leads to the suppression of the surfaces states, opening the band gaps of the slab systems up to the corresponding bulk energy limits. For most AO-terminated ABO${_3}$(001) perovskite surfaces, a CO${_2}$ coverage of 0.25 was found to be sufficient to fully suppress the surface states, whereas the same effect can only be achieved at 0.50 CO${_2}$ coverage for the BO${_2}$ terminations. The largest band gap modulation among the AO-terminated surfaces was found for SrHfO${_3}$(001) and BaHfO${_3}$(001), whereas the most profound effect among the BO${_2}$ terminations was identified for SrTiO${_3}$(001) and BaTiO${_3}$(001). Based on these results and considering practical difficulties associated with measuring conductivity of highly resistive materials, TiO${_2}$-terminated SrTiO${_3}$(001) and BaTiO${_3}$(001) were identified as the most prospective candidates for chemiresistive CO${_2}$ sensing applications.