Cu2O/InGaN heterojunction thin films with enhanced photoelectrochemical activity for solar water splitting. (August 2020)

• Record Type: Journal Article
• Authors: Alizadeh, Mahdi; Tong, Goh Boon; Qadir, Karwan Wasman; Mehmood, Muhammad Shahid; Rasuli, Reza
• Is Part Of: Renewable energy. Volume 156(2020)
• Page Start: 602
• Page End: 609
• Publication Date: 2020-08
• Subjects: Cu2O/InGaN heterojunction -- Photoelectrochemical behavior -- Solar water splitting -- Thin films; Renewable energy sources -- Periodicals; Power resources -- Periodicals; Énergies renouvelables -- Périodiques; Ressources énergétiques -- Périodiques; 333.794
• DOI: 10.1016/j.renene.2020.04.107
• Languages: English
• ISSNs: 0960-1481

Abstract

Abstract: We study Cu2 O/InGaN heterojunction thin films with different thicknesses of Cu2 O layer as a photoanode in photoelectrochemical (PEC) water splitting cell. Results show that the bandgap energy of Cu2 O/InGaN heterojunction thin films is 2.60–2.72 eV and, according to Vegard's law, the indium content of the InGaN thin film is 22%. Electrochemical impedance spectroscopy shows the charge-transfer resistance value of about 0.4 kΩ for the optimized sample revealing enhanced charge separation and transfer at the interface. A maximum photocurrent density of 0.16 mA cm −2 at 0.5 V vs. Ag/AgCl was obtained for the Cu2 O/InGaN heterojunction thin films with an overall thickness of 250 nm. The obtained value is 4.2 and 3.2 times higher than that of pure InGaN and Cu2 O thin films photoanodes, respectively. We showed charge separation mechanism in the Cu2 O/InGaN heterojunction photoelectrodes. According to our model, gradient energy bandgap reduce the recombination rate of photo-induced electron-hole pairs, and significantly enhance the PEC performance. Highlights: Cu2 O/InGaN heterojunctions thin films were grown by MOCVD and sputtering methods. Cu2 O layer on InGaN thin films significantly improved the photocurrent density. Photocurrent density of optimized InGaN/Cu2 O is 4.2 times higher than that of InGaN. The charge-transfer resistance value of 0.4 kΩ was obtained for optimized sample. Enhanced charge separation at the interface were deduced from the band structure.