PAN-assisted preparation of Bi2MoO6 with enhanced photocatalytic CO2 reduction performance

Abstract

In this study, to improve photocatalytic CO₂ reduction efficiency of Bi₂MoO₆-based photocatalysts, Bi₂MoO₆ (BMO) was synthesized via a solvothermal method with the assistance of polyacrylonitrile (PAN). Scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques were utilized to evaluate the microstructures, phases, and elemental compositions of the samples. Additionally, the separation and migration efficiency of photogenerated charge pairs during the photocatalytic process were analyzed in detail using surface photovoltage spectroscopy (SPS), photoluminescence spectrum (PL), transient photocurrent density (TPR), and electrochemical impedance spectroscopy (EIS). In comparison with the reference sample, the specific surface area of 2 % BMO (mass ratios of PAN/Bi(NO₃)₃·5H₂O is 2 %) has been increased to 39.6 m²/g, which increases by 0.9 times compared to the reference sample. The successful introduction of oxygen vacancies (OVs) in Bi₂MoO₆ was confirmed by low-temperature electron paramagnetic resonance (EPR) and X-ray photoelectron spectroscopy (XPS), and suitable OVs is favorable for separation and migration of the photogenerated carriers. The experimental results indicate that the separation efficiency of photogenerated carriers in the PAN-BMO photocatalyst is significantly boosted in contrast to the reference sample. Furthermore, all photocatalysts exhibit higher photocatalytic CO₂ reduction activity than the reference sample. It is noteworthy that the 2 % BMO sample shows the highest photocatalytic CO₂ reduction activity, and the average photocatalytic CO₂ reduction yield over the 2 % BMO reaches 2.16 μmol g⁻¹ h⁻¹, which is 2.25 times higher than that on the reference sample (0.96 μmol g⁻¹ h⁻¹). In view of the findings, photocatalytic CO₂ reduction mechanism for BMO with OVs was rationally proposed.