Transferred monolayer MoS2 onto GaN for heterostructure photoanode: Toward stable and efficient photoelectrochemical water splitting

• Published in: Scientific reports 2019-12, Vol.9 (1), p.1-11, Article 20141
• Main Authors: Hassan, Mostafa Afifi, Kim, Min-Woo, Johar, Muhammad Ali, Waseem, Aadil, Kwon, Min-Ki, Ryu, Sang-Wan
• Format: Article
• Language: English
• Subjects: 639/301/299/890; 639/301/357; Alternative energy sources; Energy conversion; Humanities and Social Sciences; Molybdenum disulfide; multidisciplinary; Organic chemicals; Science; Science (multidisciplinary); Silver chloride; Solar energy; Splitting
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-019-56807-y

Solar-driven photoelectrochemical water splitting (PEC-WS) using semiconductor photoelectrodes is considered a promising solution for sustainable, renewable, clean, safe and alternative energy sources such as hydrogen. Here, we report the synthesis and characterization of a novel heterostructure MoS 2 /GaN to be used as a photoanode for PEC-WS. The heterostructure was synthesized by metal-organic chemical vapor deposition of single crystalline GaN onto a c-plane sapphire substrate, followed by the deposition of a visible light responding MoS 2 monolayer (E g  = 1.9 eV) formed by a Mo-sulfurization technique. Our experimental results reveal that MoS 2 /GaN photoanode achieved efficient light harvesting with photocurrent density of 5.2 mA cm −2 at 0 V vs Ag/AgCl, which is 2.6 times higher than pristine GaN. Interestingly, MoS 2 /GaN exhibited a significantly enhanced applied-bias-photon-to-current conversion efficiency of 0.91%, whereas reference GaN yielded an efficiency of 0.32%. The superior PEC performance of the MoS 2 /GaN photoelectrode is mainly related to the enhanced light absorption due to excellent photocatalytic behavior of MoS 2 , which reduces charge transfer resistance between the semiconductor and electrolyte interface, and the improvement of charge separation and transport. This result gives a new perspective on the importance of MoS 2 as a cocatalyst coated onto GaN to synthesize photoelectrodes for efficient solar energy conversion devices.