Promoted charge carrier dynamics in electrospun tungsten oxide nanofiber water-splitting photoanodes through incorporation of highly dispersed Ag/Ag2O core-shell nanoparticles

Fine-tuning dopant concentration in nanostructured photoanodes is crucial for enhancing photoelectrochemical (PEC) water-splitting efficiency. This study demonstrates that carefully adjusted Ag doping in electrospun WO 3 nanofibers leads to the formation of well-dispersed Ag/Ag 2 O core–shell nanoparticles. Optimal 4 mol% Ag doping induces synergistic effects, including extended visible light absorption via band-tail states, preferential (002) facet exposure, increased donor density, Fermi-level pinning, and enhanced surface hydroxylation—all promoting efficient charge separation, interfacial transfer, and transport. As a result, the optimized photoanode achieves a photoconversion efficiency (PCE) of 4.34 % and a photocurrent density of 9.02 mA cm −2 at 1.23 V RHE , representing a 33-fold improvement over undoped WO 3 . Structural, optical, and electrochemical characterizations—including TEM, SEM, XRD, XPS, UV–Vis spectroscopy, Mott-Schottky, and EIS analyses—confirm the strong correlation between optimal Ag doping and PEC enhancement. This work provides mechanistic insights into dopant-induced electronic and interfacial modifications for advancing high-performance nanostructured metal-oxide photoanodes. • Fine-tuned Ag doping in WO 3 nanofibers modified electronic and catalytic traits. • 4 mol% Ag-doped WO 3 photoanode achieves 9.02 mA cm −2 and 4.34 % PCE. • Optical band gap reduced from 2.87 eV to 2.11 eV at optimal Ag loading. • Ag/Ag 2 O core–shell nanocatalysts enhance charge transfer and OER activity. • Improved charge dynamics via O vacancies, Fermi-level pinning, and –OH groups.