TiO2 Nanorods Co-decorated with Metal-Free Carbon Materials for Boosted Photoelectrochemical Water Oxidation

The key challenge for solar water oxidation is to develop photoanodes with high charge transfer and separation efficiency as well as rapid surface reaction kinetics. Herein, the double metal-free carbon materials, including carbon dots (CDs) and ultra-thin carbon nitride (UCN), were coupled with TiO2 nanorods (CDs/UCN/TiO2) to enhance photoelectrochemical (PEC) activity. Attributed to the integrated effect of UCN and CDs, the designed ternary CDs/UCN/TiO2 photoanode exhibits a photocurrent density of 1.43mAcm(-2), which is 3.0-fold higher than that of the bare TiO2 nanorods. In detail, the UCN can efficiently accelerate the charge separation and restrict the electron/hole recombination, owing to the close contact heterojunction. Meanwhile, the CDs can significantly facilitate H2O2 decomposition, as demonstrated by scanning electrochemical microscopy (SECM), as they induce rapid reaction kinetics. Importantly, such constructed photoanodes modified with double metal-free carbon materials provide great potential for future progress in PEC water splitting through a simple decoration strategy with metal-free carbon materials.