Question

Plot on the same energy diagram having the vacuum as zero:

(A) the absolute electrochemical potentials, under standard conditions, 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 conduction band while reaction (ii) occurs by electron exchange with the valence band? Under such conditions, which of the two semiconductors can achieve water splitting (2H2O ® 2H2 + O2)?

(B) The position of the band gaps of the compound semiconductors SrTiO3 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.

Answer 1