GaN nano-pyramid arrays as an efficient photoelectrode for solar water splitting. (11th October 2016)

• Record Type: Journal Article
• Authors: Hou, Y; Yu, X; Syed, Z Ahmed; Shen, S; Bai, J; Wang, T
• Is Part Of: Nanotechnology. Volume 27:Number 45(2016)
• Publication Date: 2016-10-11
• Subjects: photoelectrode -- water splitting -- hydrogen generation -- GaN; Nanotechnology -- Periodicals; Nanotechnology -- Periodicals; Nanotechnology; Publications périodiques; Nanotechnologies; Periodicals; 620.5
• DOI: 10.1088/0957-4484/27/45/455401
• Languages: English
• ISSNs: 0957-4484

Abstract

Abstract: A prototype photoelectrode has been fabricated using a GaN nano-pyramid array structure grown on a cost-effective Si (111) substrate, demonstrating a significant improvement in performance of solar-powered water splitting compared with any planar GaN photoelectrode. Such a nano-pyramid structure leads to enhanced optical absorption as a result of a multi-scattering process which can effectively produce a reduction in reflectance. A simulation based on a finite-difference time-domain approach indicates that the nano-pyramid architecture enables incident light to be concentrated within the nano-pyramids as a result of micro-cavity effects, further enhancing optical absorption. Furthermore, the shape of the nano-pyramid further facilitates the photo-generated carrier transportation by enhancing a hole-transfer efficiency. All these features as a result of the nano-pyramid configuration lead to a large photocurrent of 1 mA cm −2 under an illumination density of 200 mW cm −2, with a peak incident photon-to-current conversion efficiency of 46.5% at ∼365 nm, around the band edge emission wavelength of GaN. The results presented are expected to pave the way for the fabrication of GaN based photoelectrodes with a high energy conversion efficiency of solar powered water splitting.