Applied Science and Convergence Technology 2022; 31(2): 51-55
Published online March 30, 2022
Copyright © The Korean Vacuum Society.
aDepartment of Electronic and Information Materials Engineering, Division of Advanced Materials Engineering and Research Center of Advanced Materials Development, Jeonbuk National University, Jeonju 54896, Republic of Korea
bDivision of Advanced Materials Engineering, Jeonbuk National University, Jeonju 54896, Republic of Korea
cElectronics and Telecommunications Research Institute, Daejeon 34129, Republic of Korea
dDepartment of Physics, Kunsan National University, Kunsan 54150, Republic of Korea
eDepartment of Physics, Kangwon National University, Chuncheon 24341, Republic of Korea
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We report improved photoelectrochemical water splitting (PEC-WS) using GaN nanowires (NWs) with reverse-mesa structures (RMNWs) formed on Si(111) as a photoanode material. The GaN-RMNW photoanode exhibited a current density of 2.62 mA/cm2 and an applied photonto-current efficiency of 1.65% at 0.6 V versus a reversible hydrogen electrode. These values are considerably higher than those (1.16 mA/cm2 and 1.24%) of the photoanode based on GaN NWs with uniform hexagonal-pillar structures. The improved PEC-WS using the GaN-RMNW photoanode is attributed to the increase in the number of carriers participating in the PEC-WS reaction. The increase in the effective carriers is primarily due to the high crystallinity of the GaN RMNWs and the increase in the absorption rate of the incident light by the reverse-mesa structures. In addition, the energy-band structure between the GaN RMNWs and Si(111) promotes the separation of photogenerated carriers. Consequently, it reduces carrier recombination inside the photoanode, thereby enabling a high-performance PEC-WS.
Keywords: Photoelectrochemical water splitting, GaN nanowire, Reverse-mesa structure, High crystallinity, Photoanode