Phase transition-induced band edge engineering of BiVO

Abstract

Through phase transition-induced band edge engineering by dual doping with In and Mo, a new greenish BiVO[subscript 4] (Bi[subscript 1-X]In[subscript X]V[subscript 1-X]Mo[subscript X]O[subscript 4]) is developed that has a larger band gap energy than the usual yellow scheelite monoclinic BiVO[subscript 4] as well as a higher (more negative) conduction band than H[superscript +]/H[subscript 2] potential [0 VRHE (reversible hydrogen electrode) at pH 7]. Hence, it can extract H[subscript 2] from pure water by visible light-driven overall water splitting without using any sacrificial reagents. The density functional theory calculation indicates that In[superscript 3+]/Mo[superscript 6+] dual doping triggers partial phase transformation from pure monoclinic BiVO[subscript 4] to a mixture of monoclinic BiVO[subscript 4] and tetragonal BiVO[subscript 4], which sequentially leads to unit cell volume growth, compressive lattice strain increase, conduction band edge uplift, and band gap widening.