Fig. 4.

a Schematic illustration of photocharging mechanism of the proposed VO₂/ZnO Zn-ion photo-battery. b GDC curves of the photo-batteries at 200 mA g⁻¹ both in dark and illuminated conditions (~ 455 nm and intensity 12 mW cm⁻²) after one formation cycle. Reproduced with permission [91].

Copyright 2021, Royal Society of Chemistry. c CV curves of CeO₂/MnO₂-CFP electrodes in dark and under visible light illumination (400–780 nm) at the scan rate of 5 mV s⁻¹. d Band structure diagram of the CeO₂/MnO₂ heterojunction. Reproduced with permission [81]. Copyright 2022, Tsinghua University Press