Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, United Kingdom.
J Chem Phys. 2012 Oct 21;137(15):154706. doi: 10.1063/1.4758319.
We present the results of a density functional theory investigation of the surfaces of rutile-like vanadium dioxide, VO(2)(R). We calculate the surface energies of low Miller index planes and find that the most stable surface orientation is the (110). The equilibrium morphology of a VO(2)(R) particle has an acicular shape, laterally confined by (110) planes and topped by (011) planes. The redox properties of the (110) surface are investigated by calculating the relative surface free energies of the non-stoichiometric compositions as a function of oxygen chemical potential. It is found that the VO(2)(110) surface is oxidized with respect to the stoichiometric composition, not only at ambient conditions but also at the more reducing conditions under which bulk VO(2) is stable in comparison with bulk V(2)O(5). The adsorbed oxygen forms surface vanadyl species much more favorably than surface peroxo species.
我们呈现了锐钛矿型二氧化钒（VO(2)(R)）表面的密度泛函理论研究结果。我们计算了低晶面指数平面的表面能，发现最稳定的表面取向是（110）。VO(2)(R)颗粒的平衡形态为针状，由（110）平面侧向限制，顶部为（011）平面。通过计算非化学计量组成的相对表面自由能作为氧化学势的函数，研究了（110）表面的氧化还原性质。结果发现，与体相 V(2)O(5)相比，VO(2)(110)表面在环境条件下以及在更还原的条件下相对于化学计量组成被氧化，体相 VO(2)在此条件下是稳定的。吸附氧形成表面钒氧物种比表面过氧物种更有利。
