Comparing the Performance of WO3 Nanoparticles and Nanofibers for Photoelectrochemical Water Splitting and Photocatalytic Dye Degradation
Juan Carlos Expósito-Gálvez a, Ludek Hromadko b c, Francisco J. Peón-Díaz d e, Jan M Macak b c, Gerko Oskam a f
a Center for Nanoscience and Sustainable Technologies (CNATS). Department of Physical, Chemical and Natural Systems, Universidad Pablo de Olavide, Sevilla, Spain
b Center of Materials and Nanotechnologies, Faculty of Chemical Technology, University of Pardubice, Pardubice, Czech Republic
c Central European Institute of Technology, Brno University of Technology, Brno, Czech Republic
d Ph.D. Program in Sciences with a Chemistry Mention, Universidad Técnica Federico Santa María-Universidad Valparaiso, Valparaiso, Chile
e Institute of Chemistry and Biochemistry, Universidad de Valparaiso, Valparaiso, Chile
f Department of Applied Physics, CINVESTAV-IPN, Mérida, Yucatán, México
Proceedings of The Future of Hydrogen: Science, Applications and Energy Transition (H2Future)
Ibiza, Spain, 2024 April 17th - 19th
Organizers: Carolina Gimbert Suriñach, Sixto Gimenez Julia and Emilio Palomares
Oral, Juan Carlos Expósito-Gálvez, presentation 011
Publication date: 27th February 2024

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 [1]. It should be considered that the performance of the photoelectrode depends on the morphology of the nanostructured material [2]. 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 [3]. To elucidate the complex charge carriers dynamics, intensity-modulated photocurrent spectroscopy (IMPS) is used.  The photocatalytic dye degradation kinetics are faster for the nanofibers, due to their larger specific surface area related to the smaller size of the particles that constitute the fibers. On the other hand, the photoelectrochemical performance is essentially the same for both materials with one loop in the 4th quadrant of the IMPS spectra. This fundamental difference in performance is demonstrated to be due to the influence of trap-limited electron transport [4] on the collection efficiency of photoelectrons, rather than hole transfer to the solution, in the interconnected and nanostructured films, required for the observation of photocurrent in the external circuit, whereas photocatalysis is more surface-driven. These results illustrate the intricacies of photocatalytic processes and indicate that the nanomaterial morphology needs to be optimized for each specific application, keeping in mind the charge carrier dynamics that govern performance [5].

The authors gratefully acknowledge funding from Consejería de Universidad, Investigación e Innovación of the Junta de Andalucía (Spain) under grant ProyExcel_00543, the Ministerio de Ciencia, Innovación y Universidades (Spain) under grant PID2019–110430GB- C22, and the Ministerio de Universidades (Spain) and Universidad Pablo de Olavide under the Beatriz Galindo Program, grants BEAGAL 18/ 00077 and BGP 18/00060. The authors also would like to thank for the support with characterization and materials analysis provided by INMALAB (Universidad Pablo de Olavide). F. Peón thanks the financial support from ANID National Doctorate Fellowship [212003662]; Dirección de Postgrados y Programas, Universidad Técnica Federico Santa María, Chile [PIIC 2021, PIIC 2022; Internship Scholarship 2022 and 2023].

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