Design of nanohoneycomb structured Ta3N5/WO3 Z-scheme for enhanced visible light photocatalytic hydrogen evolution

Ta3N5 has suitable band positions for visible light photocatalytic hydrogen production from water splitting. However, fast self-recombination of electrons and holes is a drawback for its low efficiency. A Ta3N5/WO3 Z-scheme was therefore considered to solve this problem. Furthermore, a nanohoneycomb (nHC) structure was designed and fabricated based on solution-based nanosphere lithography to offer higher surface area for reaction. The cell size of the nHC was controlled by using 400-, 200-, and 100-nm polystyrene nanospheres as the mask. Under visible light irradiation, the hydrogen generation rates of Ta3N5@WO3 film and Ta3N5@100-nm WO3 nHC were measured to be 4.6 and 8.1 μmol/g·h, respectively, whereas that of pure Ta3N5 nHC was negligible. With deposition of Pt cocatalyst, the hydrogen generation rates for Ta3N5@WO3 film and Ta3N5@100-nm WO3 nHC were further raised to 9.9 and 16.6 μmol/g·h, confirming the effectiveness of the structure design.