Phase transition-induced band edge engineering of BiVO 4 to split pure water under visible light

Hydrogen has been recognized as one of the most promising energy carriers for the future, because it can generate enormous energy by clean combustion chemistry without any greenhouse gas emissions. Water splitting under visible light irradiation is an ideal route to cost-effective, large-scale, and sustainable hydrogen production, but it is challenging, because it requires a rare photocatalyst that carries a combination of suitable band gap energy, appropriate band positions, and photochemical stability. To create this rare photocatalyst, we engineered the band edges of BiVO 4 by simultaneously substituting In 3+ for Bi 3+ and Mo 6+ for V 5+ in the host lattice of monoclinic BiVO 4 , which induced partial phase transformation from pure monoclinic BiVO 4 to a mixture of monoclinic BiVO 4 and tetragonal BiVO 4 . Through phase transition-induced band edge engineering by dual doping with In and Mo, a new greenish BiVO 4 (Bi 1-X In X V 1-X Mo X O 4 ) is developed that has a larger band gap energy than the usual yellow scheelite monoclinic BiVO 4 as well as a higher (more negative) conduction band than H + /H 2 potential [0 V RHE (reversible hydrogen electrode) at pH 7]. Hence, it can extract H 2 from pure water by visible light-driven overall water splitting without using any sacrificial reagents. The density functional theory calculation indicates that In 3+ /Mo 6+ dual doping triggers partial phase transformation from pure monoclinic BiVO 4 to a mixture of monoclinic BiVO 4 and tetragonal BiVO 4 , which sequentially leads to unit cell volume growth, compressive lattice strain increase, conduction band edge uplift, and band gap widening.