title: Improved photoelectrochemical performance of GaN nanopillar photoanodes.
abstract: In this work, we report on the photoelectrochemical (PEC) investigation of n-GaN nanopillar (NP) photoanodes fabricated using metal organic chemical vapour deposition and the top-down approach. Substantial improvement in photocurrents is observed for GaN NP photoanodes compared to their planar counterparts. The role of carrier concentration and NP dimensions on the PEC performance of NP photoanodes is further elucidated. Photocurrent density is almost doubled for doped NP photoanodes whereas no improvement is noticed for undoped NP photoanodes. While the diameter of GaN NP is found to influence the onset potential, carrier concentration is found to affect both the onset and overpotential of the electrodes. Optical and electrochemical impedance spectroscopy characterisations are utilised to further explain the PEC results of NP photoanodes. Finally, improvement in the photostability of NP photoanodes with the addition of NiO as a co-catalyst is investigated.
authors.affiliation: Department of Electronic Materials Engineering, Research School of Physics and Engineering, The Australian National University, Canberra, ACT 2601, Australia.
authors.forename: Parvathala Reddy
authors.initials: PR
authors.lastname: Narangari
authors.forename: Siva Krishna
authors.initials: SK
authors.lastname: Karuturi
authors.forename: Mykhaylo
authors.initials: M
authors.lastname: Lysevych
authors.forename: Hark
authors.initials: H
authors.lastname: Hoe Tan
authors.forename: Chennupati
authors.initials: C
authors.lastname: Jagadish