High efficiency GaN nanowire/Si photocathode for photoelectrochemical water splitting

Photoelectrochemical (PEC) water splitting is one of the most promising technologies to convert solar energy into chemical energy in the form of hydrogen production. III-nitride semiconductors are promising materials to realize high efficiency photoelectrodes: their energy bandgap can be varied across nearly the entire solar spectrum by changing the alloy compositions and the band edge positions straddle water oxidation and reduction potentials under deep visible light irradiation. In this work, we report on the demonstration of a Si-based photocathode, which consists of n+-GaN nanowire arrays grown on n+-p Si substrate and enables relatively high efficiency (~9%) and highly stable solar water splitting.