The design of high performance photoanode of CQDs/TiO2/WO3 based on DFT alignment of lattice parameter and energy band, and charge distribution.

[Display omitted] • CQDs/TiO 2 /WO 3 is designed on the basis of dual alignment and charge distribution. • TiO 2 epitaxially grow on WO 3 with ~3% lattice mismatch to form heterojunction. • The built-in field of TiO 2 /WO 3 can inhibit bulk recombination with band alignment. • CQDs can extend visible light absorption and shift onset potential cathodically. • PEC water splitting performance of CQDs/TiO 2 /WO 3 has been significantly improved. Photoanode is the key issue for photoelectrocatalytic (PEC) water splitting and organics degradation. However, it always faces several restrictions including severe photocorrosion, low charge separation and transfer efficiencies, poor visible light harvesting, and sluggish interfacial reaction kinetics, which often required a variety of modifications with only low improvements achieved. Herein, a high performance CQDs/TiO 2 /WO 3 photoanode was designed on the basis of density function theory (DFT) alignment of lattice parameters and energy band, and charge distribution. The TiO 2 /WO 3 heterojunction can abate photocorrosion through the hetero-epitaxial growth of TiO 2 (0 0 1) on WO 3 (0 0 2) for the lattice mismatch <3% eliminating dangling bonds, with high corrosion resistance and photostability of TiO 2. As the built-in field constructed by a staggered band alignment structure with the valence band offset (VBO) of 0.51 eV, the photogenerated carriers transfer and separation are promoted dramatically. Through the DFT calculations, the sunlight absorption wavelength can be extended, and the interfacial reaction kinetics can be expedited with the modification of carbon quantum dots (CQDs) on TiO 2 /WO 3 , due to the narrower bandgap (E g) and the accumulation of electrons at TiO 2 side. The DFT designed CQDs/TiO 2 /WO 3 photoanode significantly increase photocurrent density from 0.90 to 2.03 mA cm−2 at 1.23 V, charge separation efficiency from 56.3 to 79.2% and charge injection efficiency from 51.2 to 70.4%, and extend light absorption edge from 455 to 463 nm over pristine WO 3 , with better photostability and lower holes-to-water resistance. [ABSTRACT FROM AUTHOR]