Efficient photoelectrochemical water splitting of CaBi6O10 decorated with Cu2O and NiOOH for improved photogenerated carriers

Broadening the light absorption and accelerating the separation of photogenerated electron-hole pairs is of crucial importance for strongly enhancing the photoelectrochemical (PEC) water splitting performances of photoelectrode. In this paper, a novel CaBi6O10/Cu2O/NiOOH photoanode for photoelectrochemical water splitting is prepared, where, the NiOOH acts as water oxidation catalyst to accelerate water oxidation taking place in the interfaces between electrode and electrolyte, Cu2O is chosen to extend the absorption range of the light absorber, enhancing an efficient separation and transfer of the electron-hole pairs. This triple CaBi6O10/Cu2O/NiOOH photoanode negatively shifts the onset potential and exhibits an improved photocurrent density 1.89 mA·cm−2 at 1.23 V vs RHE, which is 1.4 and 4.8 times higher compared to CaBi6O10/Cu2O and CaBi6O10, respectively. More importantly, the CaBi6O10/Cu2O/NiOOH electrode shows excellent photoelectrochemical stability in comparison with CaBi6O10/Cu2O after 2 h irradiation. The amazing photoelectrochemical performance is due to the broader light absorption spectrum, the improved photogenerated carriers separation, transfer and consumption. The research results demonstrate a promising ternary semiconductor structure, which can improve photoelectrochemical performance effectively. Moreover, these results also imply that the CaBi6O10/Cu2O/NiOOH heterojunction structure has a great potential application for photoelectrochemical water splitting systems.