Electrodeposition of ZnO nanoflake-based photoanode sensitized by carbon quantum dots for photoelectrochemical water oxidation

We report a promising simple strategy for improving the performance of the photoanode for photoelectrochemical (PEC) water oxidation. Three-dimentional hierarchical ZnO nanoflake arrays with abundant porosity and small thickness on fluorine-doped tin oxide glass substrate (FTO) was prepared with electrodeposition. The ZnO nanoflake-based photoanode exhibits superior photoresponse and PEC capability. Furthermore, the ZnO photoanode sensitized by carbon quantum dots (CQDs) can further PEC performance due to the narrower bandgap of CQDs and the improved efficiency of photogenerated electrons transfer from CQDs to ZnO nanostructures. The morphology and properties of the sample were examined by scanning electron microscopy (SEM), cross-section SEM, UV–vis spectra, X-ray photoelectron spectra (XPS), FT-IR, X-ray diffractometry (XRD) and electrical measurements.