Comparing the performance of WO3 nanoparticles and nanofibers: Photocatalytic dye degradation versus photoelectrochemical water oxidation

Abstract

Nanostructured WO3 is a widely studied, attractive material for photocatalysis applications, ranging from degradation of organic contaminants to water photooxidation, related to its relatively small bandgap, good stability, and adequate charge transport and charge transfer efficiencies. In catalysis, a large surface-to-volume ratio generally improves activity; however, this is not always the case for photoelectrochemical systems. In this work, we compare the photocatalytic and photoelectrochemical performance of commercial WO3 nanoparticles with that of WO3 nanofibers prepared by centrifugal spinning. The photocatalytic dye degradation kinetics are faster for the nanofibers, related to their larger specific surface area. On the other hand, the photoelectrochemical performance is essentially the same for both materials. This fundamental difference in performance is demonstrated to be due to the influence of trap-limited electron transport on the collection efficiency of photoelectrons, required for the observation of photocurrent in the external circuit, whereas photocatalysis is more surface-driven.