Band Gap Engineering in NaBiO3·2H2O/NaBiO3·xH2O Heterostructures for High Photoelectronic Response

Abstract

High photoelectronic response with a broad spectral range in photoelectric materials is of great importance for photovoltaic and photocatalytic applications. However, the existing photoelectric materials, such as TiO2 and α-Fe2O3, exhibit only high photoelectronic response or only broad spectral response because of the wide band gap limitation of light absorbance or low photogenerated charge separation efficiency. Here, we report NaBiO3·2H2O annealed at a given temperature to form NaBiO3·2H2O/NaBiO3·xH2O heterostructures, which efficiently drives the photogenerated charge separation in a broad spectral range. The best performance of the wide photoelectronic response and high surface photovoltage was obtained in the sample annealed at 130 °C. The high surface photovoltage with a wide spectral range is attributed to the band gap engineering of NaBiO3·2H2O/NaBiO3·xH2O heterostructures for efficient photogenerated charge separation. These findings regarding the use of optimized NaBiO3·2H2O/NaBiO3·xH2O heterostructures suggest that fine-tuning the heterostructure of the photoelectric materials is an effective approach for improving the photoelectrical performance in optoelectronic applications.