Cu2O/InGaN heterojunction thin films with enhanced photoelectrochemical activity for solar water splitting
2020
Alizadeh, Mahdi | Tong, Goh Boon | Qadir, Karwan Wasman | Mehmood, Muhammad Shahid | Rasuli, Reza
We study Cu₂O/InGaN heterojunction thin films with different thicknesses of Cu₂O layer as a photoanode in photoelectrochemical (PEC) water splitting cell. Results show that the bandgap energy of Cu₂O/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 Cu₂O/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 Cu₂O thin films photoanodes, respectively. We showed charge separation mechanism in the Cu₂O/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.
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