posted on 2020-08-31, 18:34authored byTilak Das, Xavier Rocquefelte, Stéphane Jobic
Finding
absolute reference energy from first-principles calculations
to align redox positions of valence band top and hence conduction
band bottom of bulk inorganic photocatalysts is still a challenge.
A theoretical methodology is proposed herein based on first-principles
calculations using the state-of-the-art hybrid density functional
theory from Heyd–Scuseria–Ernzerhof. Both oxide and
nonoxide materials, known for their potential capability for photocatalysis,
i.e., rutile and anatase TiO2; wurtzite ZnO; rutile SnO2; and the blende phase of GaP, GaAs, InP, ZnTe, CdS, CdSe,
and SiC, have been studied. The calculated band edges around the fundamental
band gap of these compounds are realigned, in reference to the corrected
vacuum energy level from the probe’s core energy state, i.e.,
the 1s2 state of an unreactive helium atom. The calculated
ab initio positioning of valence and conduction band extrema is compared
to the available experimental data, and our prediction is best fitted
within a mean absolute error of 0.2 eV.