III−V Nitride Epilayers for Photoelectrochemical Water Splitting:  GaPN and GaAsPN

Abstract

Epilayers of single-crystal GaAsPN and GaPN semiconductor samples with varying nitrogen compositions were photoelectrochemically characterized to determine their potential to serve as water splitting photoelectrodes. The band gap and flatband potentials were determined and used to calculate the valence and conduction band edge energies. The band edges for all compositions appear to be too negative by more than 500 mV for any of the materials to effect light-driven water splitting without an external bias. Corrosion analysis was used to establish material stability under operating conditions. GaPN was found to show good stability toward photocorrosion; on the other hand, GaAsPN showed enhanced photocorrosion as compared to GaP.

Local structural models of complex oxygen- and hydroxyl-rich GaP/InP(001) surfaces

“…Oxygen adsorption is thermodynamically favored with respect to O 2 gas (dry atmospheric conditions; left axis in Fig. 3), in agreement with observations of spontaneous surface oxidation of InP(001) and GaP(001) 8,9,13,26 . However, only Ga-O-Ga is thermodynamically favored with respect to H 2 /H 2 O (right axis in Fig.…”

“…This conclusion derives in part from experiments which found that cathodic corrosion requires exciton generation, and that simple injection of electrons via application of current in the dark did not lead to electrode degradation 8 . This implies that the presence of holes is key to the corrosion mechanism, which probably derives from a shift in the local potential from regional hole buildup that is not compensated by the electrolyte solution.…”

“…Unfortunately, efficiency comes at the expense of short device lifetime due to fast degradation of the electrode [6][7][8][9][10][11][12] . In order to tune stability and reactivity, a better understanding of the morphology and composition of the semiconductor surface under realistic environmental conditions is required; structural features can then be linked to specific electronic properties relevant to photocatalysis and photocorrosion.…”

Ab initio modeling of water-semiconductor interfaces for direct solar-to-chemical energy conversion

“…All tested configurations show that incorporation of oxygen is strongly thermodynamically favored with respect to the clean surface in the presence of gaseous O 2 , in agreement with experimental observations of high surface oxygen contamination. 7,9,18 When taken with respect to water, however, incorporation is endothermic.…”

A facile way to prepare visible light driven tin oxide based photoanode and its photoelectrochemical water splitting properties

“…Meanwhile, these single junction and multi-junction tandem cell materials and film preparation methods employed in photovoltaic cell were also greatly performed in PEC, such as p-GaP, p-GaAs, p-InP, InGaP, p-GaInP 2 /GaAs P/n, CICS, etc. [12][13][14]. Unfortunately, most of these materials failed to satisfy the requirements mentioned above simultaneously, and lag behind the phased target (efficiency, cost, stability) set by DOE periodically.…”