The coupling effect of carbon spheres and cobalt-involved carbon nitrides stacked on TiO2 nanorod arrays for promoted solar water oxidation

Abstract

Photoanode materials typically exhibit good stability and environmentally and economically properties in solar water splitting cells, while they always suffer from the narrow light absorption range, heavy surface charge combination and sluggish surface reaction kinetics. Herein, we design an efficient and reproducible photoanode by stacking amorphous carbon spheres (CSs) and cobalt-involved carbon nitrides (Co-CNs) on surface of TiO2 nanorod arrays. CSs work as light sensitizer for broadening the light absorption range of photoanode and promoting the utilization of solar energy, which further improved by Co-CNs partially. In addition, CSs increase the conductivity of photoanode, as a transport channel for improving the charge migration. Co-CNs introduce many active sites on surface of photoanode for facilitated solar water oxidation. The best constructed TiO2/CSs/Co-CNs photoanode exhibits an impressive photocurrent density of ∼1.73 mA/cm2 (at 1.23 V vs RHE). The staking method of various functional materials provides one promising strategy for the modification of catalysts.