Harnessing light energy: Electrodeposited ZnO:ZnMn2O4 nano-heterojunction as promising electrode for photo-rechargeable supercapacitors

• Published in: Materials research bulletin 2024-06, Vol.174, p.112722, Article 112722
• Main Authors: Santhosh, P. Chinnappan, Jayakumar, Suresh, Mohideen, Mohamedazeem M., Radhamani, A.V.
• Format: Article
• Language: English
• Subjects: Electrodeposition; Photo-rechargeable SC; Photoelectrode; Solid-state supercapacitor (SC); ZnO:ZnMn2O4 heterojunction
• ISSN: 0025-5408; 1873-4227
• DOI: 10.1016/j.materresbull.2024.112722

•ZnO:ZnMn2O4 heterojunction was assembled by electrodeposition and used to fabricate solid-state supercapacitor.•The fabricated solid-state supercapacitor displayed an areal capacitance of 9.90 mF/cm2 at a current density of 110 μA/cm2.•An impressive enhancement of ∼ 122.4 % in areal capacitance was observed when exposed to UV light compared to the UV-OFF condition.•The areal energy density of the as-prepared device increased from 0.22 to 0.49 mWh/cm2 under the exposure of UV light.•The proposed band alignment diagram of the fabricated device gives insight into the photo-charging mechanism. In this study, we fabricated a novel photo-rechargeable supercapacitor using ZnO: ZnMn2O4 heterojunction prepared via a simple electrodeposition process. An aqueous symmetric supercapacitor was specifically engineered to investigate the impact of ZnO. Additionally, we fabricated a solid-state supercapacitor to examine the electrochemical performance under UV ON/OFF conditions. Under UV OFF conditions, the device exhibited an areal capacitance of 4.45 mF/cm2. When exposed to UV light, areal capacitance significantly increased to 9.90 mF/cm2, representing a 122.4 % enhancement, at 110 μA/cm2. Remarkably, the device produces a self-generated voltage of 54 mV within 60 s, eliminating the need for any external bias. Furthermore, under UV light, the device demonstrated an outstanding electrochemical performance with an areal energy density of 0.49 mWh/cm2. We also provide a comprehensive explanation of the photo-charging mechanism. The present work provides a simple approach for the construction of a highly efficient photo-rechargeable supercapacitor along with its future perspectives. [Display omitted]