TiO2 nanocrystalline for enhanced hydrogen and oxygen generation of thin film photocatalyst: from catalytic mechanism and microstructural analysis

Abstract

Anatase TiO2 nanocrystalline film prepared by using sol–gel method was assembled on TiO2 nanotubes to produce composite thin film photocatalyst and investigated as interfacial layer for the catalytic performance of Ti/TNT/N–P/NaTaO3:La (the nanostructures is Ti/TiO2 nanotubes/TiO2 nanocrystalline film/NiO film/NaTaO3:La) photocatalyst to generate hydrogen and oxygen under UV irradiation. The as-synthesized samples were characterized by FESEM, XRD, Element Mapping, UV–Vis, PL, I–V, and EIS. Characteristic analyses show that the interface between the TNT layer (TiO2 nanotubes) and P layer (NiO film) can be optimized by adjusting the number of N layers (TiO2 nanocrystalline film), thus affecting the efficiency of the photocatalyst. Compared with unformed TiO2 film, the Ti/TNT/N–P/NaTaO3:La photocatalyst with four TiO2 layers enhanced the H2 and O2 generation rate from 43.7 to 87.1 μmol/h which realized almost 2.0 times. The enhanced photocatalytic performance can be attributed to the low defect density and the effective separation of photo-generated electron–hole pairs. Furthermore, the performance stability of thin film photocatalyst was favorably showcased through multiple water splitting reactions, and the rational mechanism of improved photocatalytic property was interpreted systematically. In summary, such results have certain guiding effect on solving the weakness of composite film catalyst of interface defects and carrier recombination.