Xian Shi

Facet-Dependent Photocatalytic N2 Fixation of Bismuth-Rich Bi5O7I Nanosheets

Bismuth-rich bismuth oxyhalides (Bi-O-X; X = Cl, Br, I) display high photocatalytic reduction activity due to the promoting conduction band potential. In this work, two Bi5O7I nanosheets with different dominant facets were synthesized using either molecular precursor hydrolysis or calcination. Crystal structure characterizations, included X-ray diffraction patterns (XRD), field emission electron microscopy and fast Fourier transformation (FFT) images, showed that hydrolysis and calcination resulted in the dominant exposure of {100} and {001} facets, respectively. Photocatalytic data revealed that Bi5O7I-001 had a higher activity than Bi5O7I-100 for N2 fixation and dye degradation. Photoelectrochemical data revealed that Bi5O7I-001 had higher photoinduced carrier separation efficiency than Bi5O7I-100. The band structure analysis also used to explain the underlying photocatalytic mechanism based on the different conduction band position. This work presents the first report about the facet-dependent photocatalytic performance of bismuth-rich Bi-O-X photocatalysts.

A dual-cocatalyst-loaded Au/BiOI/MnOx system for enhanced photocatalytic greenhouse gas conversion into solar fuels

Photocatalysis is a green and economical method to convert greenhouse gases such as carbon dioxide (CO2) for environmental remediation and solar fuel generation. In a semiconductor photocatalyst system, cocatalysts play a very important role. They are not only redox-active sites but also can be used to improve the separation efficiency of photo-induced carriers. In this work, a dual-cocatalyst-loaded Au/BiOI/MnOx photocatalyst was prepared to enhance the photocatalytic reduction activity for the conversion of greenhouse gases (CO2) into solar fuels. The as-prepared BiOI, Au/BiOI, MnOx/BiOI and Au/BiOI/MnOx were characterized by using X-ray diffraction patterns (XRD), the Brunauer–Emmett–Teller (BET) method, transmission electron microscopy (TEM), UV-vis diffuse reflectance spectra (DRS) and X-ray photoelectron spectroscopy (XPS). The photocatalytic reduction results showed that Au/BiOI/MnOx had higher activity than pure BiOI, MnOx–BiOI, Au–BiOI and other BiOI-based photocatalysts for solar fuel generation. Photocurrent and electrochemical impedance (EIS) spectroscopy revealed that the efficient photo-induced carrier separation efficiency of Au/BiOI/MnOx induced the high photocatalytic activity.

Photocatalytic Mechanism Regulation of Bismuth Oxyhalogen via Changing Atomic Assembly Method

Exciton and carrier photocatalytic processes have been proved in bismuth oxyhalogen photocatalysts. But, there are no reports about how to regulate the different mechanisms to improve photocatalytic activity for different reaction. Here, we found that the photocatalytic mechanisms could be regulated by changing the assembly method of bismuth, oxygen, and halogen atoms. Reactive oxygen species (ROS) experimentals results concluded that solid solution BiOBr0.5I0.5 showed enhanced exciton photocatalytic process, and coupling 0.5BiOBr/0.5BiOI displayed improved carrier photocatalytic proces. This work promoted the understanding about solid solution and coupling for bismuth oxyhalogen.