Abstract
We investigated photoelectrochemical hydrogen generation using InGaN-based photoelectrodes with different p-GaN layer thicknesses. It was confirmed that the photocurrent density and hydrogen generation can be enhanced at zero bias between the photoelectrode and counterelectrode. We found that the maximum energy conversion efficiency was 2.0% when using an InGaN-based photoelectrode with a 20-nm-thick p-GaN layer; this was one order larger than for a photoelectrode without a p-GaN layer. The p-GaN layer can pull the potential of the InGaN layer upward, leading to efficient electron–hole separation in the photoabsorption layer and improving carrier transfer from the InGaN layer. By measuring incident photon to current efficiency, it was confirmed that the InGaN layer worked as a photoelectrode since the absorption edge wavelength was around 400 nm.
Highlights
Hydrogen generation technology using photocatalytic phenomena can use light energy to separate water into hydrogen and oxygen
The bandgap energy of the material and the valence and conduction band potentials are significantly related to the photoelectrochemical properties of the photocatalyst.1–4) Highly efficient and durable photoelectrodes for water splitting have been reported.5–9)
III-nitride semiconductors can be used as photoelectrodes for photoelectrochemical hydrogen generation from water.10–13) In general, III-nitride semiconductors are widely used in light-emitting devices but they have an excellent light absorption capability because of their tunable bandgap energy from 0.67 to 6.04 eV, which comprises most of the energy range of the solar spectrum.14–16) IIInitride semiconductor materials are expected to be suitable for use in efficient photoabsorption devices such as solar cells and photocatalysts
Summary
Hydrogen generation technology using photocatalytic phenomena can use light energy to separate water into hydrogen and oxygen. The generation of hydrogen and oxygen from the splitting of water using semiconductor photoelectrodes has been reported previously.1–4) The photoabsorption phenomenon creates electron–hole pairs in the region of the semiconductor surface. A high doping concentration in the n-layer can screen the internal electric field, pulling down the potential between the n-layer/absorption layer interface.20,21) These techniques lead to inhibition of carrier recombination in the photoabsorption layer. Such band engineering is an important factor for improving device performance
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call