Abstract
It is highly desired to improve the photoelectrochemical (PEC) performance of nanosized WO3 by artificially modulating the photogenerated electrons and holes simultaneously. Herein, WO3 nanoplates have been successfully prepared by a simple one-pot two-phase separated hydrolysis-solvothermal method, and then co-modified with RGO and phosphate acid successively by wet chemical processes. Subsequently, the as-prepared WO3-based nanoplates were immobilized on the conductive glasses to explore the PEC activities for both water oxidation to evolve O2 and phenol degradation. It is clearly demonstrated that the co-modified WO3 nanoplates exhibit significantly improved PEC activities compared with pristine WO3, especially for that with the amount-optimized modifiers by ca. 6-time enhancement. Mainly based on the evaluated hydroxyl radical amounts produced and the electrochemical impedance spectra, it is suggested that the improved PEC activities are attributed to the greatly enhanced photogenerated charge separation after chemically modification with RGO and phosphate groups to WO3, respectively by transferring electrons as the collectors and trapping holes via the formed negative field after phosphate disassociation. This work provides a feasible synthetic strategy to improve the photoactivities of nanosized WO3 for energy production and environmental remediation.
Highlights
The as-prepared WO3-based nanoplates were immobilized on the conductive glasses to explore the PEC activities for both water oxidation to evolve O2 and phenol degradation
Some works have been reported on the improved photocatalytic activities of semiconductors by coupling RGO26, 27, the photogenerated charge transfer and separation mechanism related to reduced graphene oxide (RGO) modified WO3 as photocatalyst is still ambiguous currently
In agreement with the X-ray diffraction (XRD) and diffuse reflectance spectra (DRS) results, after the modifications the morphologies of WO3 nanoplates do not change obviously, which might be due to the tiny modification amount of RGO and phosphate chemically absorbed on the WO3 surface
Summary
The as-prepared WO3-based nanoplates were immobilized on the conductive glasses to explore the PEC activities for both water oxidation to evolve O2 and phenol degradation. Based on the evaluated hydroxyl radical amounts produced and the electrochemical impedance spectra, it is suggested that the improved PEC activities are attributed to the greatly enhanced photogenerated charge separation after chemically modification with RGO and phosphate groups to WO3, respectively by transferring electrons as the collectors and trapping holes via the formed negative field after phosphate disassociation. Some works have been reported on the improved photocatalytic activities of semiconductors by coupling RGO26, 27, the photogenerated charge transfer and separation mechanism related to RGO modified WO3 as photocatalyst is still ambiguous currently. Besides transporting electrons to the modifier, to speed the transport of photogenerated holes to the surface of semiconductor becomes another feasible strategy to further benefit the effective photogenerated charge separation Both the photocatalytic water splitting to evolve O2 and the pollutant degradation are involved with the hydroxyl radicals originating from the oxidation of holes with H2O. It is meaningful to improve the PEC performance of WO3 by phosphate modification to trap holes and study the detailed process mechanism
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