Sopiha Kostiantyn V, Malyi Oleksandr I, Persson Clas, Wu Ping
Engineering Product Development, Singapore University of Technology and Design, 8 Somapah Road, 487372 Singapore, Singapore.
Phys Chem Chem Phys. 2017 Jun 28;19(25):16629-16637. doi: 10.1039/c7cp01462g.
Herein, CO chemisorption on SrTiO(001) surfaces is studied using ab initio calculations to establish new chemical sensing mechanisms. It was found that CO adsorption opens the band gap of the material. However, the mechanisms are different: the CO adsorption on the TiO-terminated surface neutralizes the surface states at the valence band (VB) maximum, whereas for the SrO-terminated surface it suppresses the conduction band (CB) minimum. For the TiO-terminated surface, the effect is explained by the passivation of dangling bonds, whereas for the SrO-terminated surface, the suppression is caused by surface relaxation. Modulation of the VB states implies a more direct change in charge distribution, and thus, the induced change in the band gap is more prominent at the TiO termination. Further, it has been shown that both CO adsorption energy and surface band gap are strongly dependent on CO coverage, suggesting that the observed effect can be utilized in sensing applications for a wide range of CO concentrations.
在此，利用从头算计算研究了CO在SrTiO(001)表面的化学吸附，以建立新的化学传感机制。研究发现，CO吸附会打开材料的带隙。然而，其机制有所不同：在TiO端接表面上的CO吸附使价带（VB）最大值处的表面态中和，而对于SrO端接表面，它抑制导带（CB）最小值。对于TiO端接表面，这种效应是由悬空键的钝化来解释的，而对于SrO端接表面，抑制是由表面弛豫引起的。VB态的调制意味着电荷分布有更直接的变化，因此，在TiO端接处带隙的诱导变化更显著。此外，研究表明，CO吸附能和表面带隙都强烈依赖于CO覆盖度，这表明所观察到的效应可用于广泛CO浓度的传感应用中。
