Abstract
III-nitride semiconductors hold tremendous promise for realizing high efficiency photoelectrodes. However, previously reported InGaN photoelectrodes generally exhibit very low photocurrent densities, due to the presence of extensive defects, dislocations, and indium phase separation. Here, we show that In0.5Ga0.5N nanowires with nearly homogeneous indium distribution can be achieved by plasma-assisted molecular beam epitaxy. Under AM1.5G one sun illumination, the InGaN nanowire photoanode exhibits a photocurrent density of 7.3 mA/cm2 at 1.2 V (vs. NHE) in 1M HBr. The incident-photon-to-current efficiency is above 10% at 650 nm, which is significantly higher than previously reported values of metal oxide photoelectrodes.
Highlights
III-nitride semiconductors hold tremendous promise for realizing high efficiency photoelectrodes
A highly efficient PEC cell requires a stable semiconductor with a suitable electronic energy band structure to absorb the majority of visible light photons in the solar spectrum and to sustain energetic photoexcited charge carriers for both hydrogen and oxygen evolution reactions.[1]
Compared to conventional metal-oxides, they offer several unique advantages: (1) The direct bandgap of InGaN can be tuned from 0.65 eV to 3.4 eV by varying the indium incorporation, which, together with their superior light absorption capability and excellent charge carrier transport properties, promises a theoretical solar-to-electricity conversion efficiency up to 62% for multi-junction solar cells;[20] (2) the conduction band minimum (CBM) and valence band maximum aAuthor to whom correspondence should be addressed
Summary
III-nitride semiconductors hold tremendous promise for realizing high efficiency photoelectrodes. Under AM1.5G one sun illumination, the InGaN nanowire photoanode exhibits a photocurrent density of 7.3 mA/cm[2] at 1.2 V (vs NHE) in 1M HBr. The incident-photon-to-current efficiency is above 10% at 650 nm, which is significantly higher than previously reported values of metal oxide photoelectrodes.
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