Plot on the same energy diagram having the vacuum as zero:
(A) the absolute electrochemical potentials, under standardconditions, of the following reactions: (i) H+/H2, (ii) O2/H2O (pH= 1). What is the spontaneous direction of reactions (i) and (ii)if reaction (i) occurs by electron exchange with the conductionband while reaction (ii) occurs by electron exchange with thevalence band? Under such conditions, which of the twosemiconductors can achieve water splitting (2H2O ® 2H2 + O2)?
(B) The position of the band gaps of the compound semiconductorsSrTiO3 and Fe2O3
SrTiO3: band gap is 3.2 eV, conduction band edge = -3.8 eV,valence band edge = -
6.9 eV. Fe2O3: band gap is 2.2 eV, conduction band edge = -4.8 eV,valence band edge =
-6.9.
