Silver-Boosted WO3/CuWO4 Heterojunction Thin Films for Enhanced Photoelectrochemical Water Splitting Efficiency

The enhancement of efficient, visible-light active photoanodes is vital for advancing photoelectrochemical (PEC) water splitting as a sustainable and environmentally friendly energy alternative. In this study, we explore the potential of WO3/CuWO4/Ag heterojunction thin films fabricated by magnetron sputtering on n-Si substrates as viable photoanodes. The synergetic effects of heterojunction formation and Ag nanoparticle dispersion contribute to superior visible-light absorption, charge transfer, and separation efficiency. The influence of Ag nanoparticle decoration achieved through solid-state dewetting phenomena was studied in terms of structural and microstructural changes and photoelectrochemical responses. Surface topography observations revealed that the WO3/CuWO4/Ag thin film exhibited the highest surface area ratio of 22.7%, approximately a threefold increase compared to the pure WO3 thin films. The photoluminescence (PL) and time-resolved photoluminescence (TRPL) results demonstrated that the heterojunction configuration promotes effective charge separation and an increased carrier lifetime of ∼20.1 ns. PEC analysis showed a substantial enhancement in photocurrent density of 1.53 mA cm–2 (1.0 V vs Ag/AgCl), approximately 2.32 times greater than that of WO3, and an increased applied bias photon-to-current efficiency (ABPE) of approximately 0.91%, compared to 0.43% for WO3 and 0.50% for WO3/CuWO4 photoanodes. Moreover, the WO3/CuWO4/Ag photoanode demonstrated remarkable long-term stability with a current density of 0.21 mA cm–2 for about 4.5 h. These findings underscore the potential of WO3/CuWO4/Ag heterojunction photocatalysts for PEC water splitting and emphasize the significance of the synergetic effect of Ag decoration and heterojunction structure formation in achieving clean and sustainable hydrogen production. Additionally, this research may inspire further studies on surface plasmon metal nanoparticle dispersion with controlled size and shape, using a simple solid-state dewetting technique for the development of efficient electrodes in next-generation water splitting applications.