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

Abstract

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 WO 3 / CuWO 4 /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 WO 3 /CuWO 4 /Ag thin film exhibited the highest surface area ratio of 22.7%, approximately a threefold increase compared to the pure WO 3 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 WO 3 , and an increased applied bias photon-to-current efficiency (ABPE) of approximately 0.91%, compared to 0.43% for WO 3 and 0.50% for WO 3 /CuWO 4 photoanodes. Moreover, the WO 3 /CuWO 4 /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 WO 3 /CuWO 4 /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.

Surface Modifications of a Vertically Grown Nanostructure for Boosting Photoelectrochemical Water-Splitting Performance

“…In the final step, the electrons and holes undergo oxidation and reduction of water, generating hydrogen and oxygen, respectively. Various types of n- and p-type semiconductor photoelectrodes have been explored, which include WO 3 , ZnO, Fe 2 O 3 , BiVO 4 , SrTiO 3 , Ta 3 N 5 , TiO 2 , etc., as n-type photoelectrodes and Cu 2 O, CuInS 2 , CaFe 2 O 4 , etc., as p-type photoelectrodes. A comparison of the PEC activity of recently reported nanostructured materials of the above-mentioned semiconductor is provided in Table .…”

Exploring the Redox Properties of the Low-Miller Index Surfaces of Copper Tungstate (CuWO4): Evaluating the Impact of the Environmental Conditions on the Water Splitting and Carbon Dioxide Reduction Processes

“…In contrast, ternary metal oxides, such as BiVO 4 , ZnWO 4 , and CuWO 4 , – have been shown to perform better than binary metal oxides in photocatalytic water splitting owing to the contribution by the metal d orbital and O 2p orbital to the valence band maxima . In particular, copper tungstate (CuWO 4 ), which is an n-type semiconductor, has attracted increasing interest for the photocatalytic water splitting process – owing to its appropriate bandgap of 1.6–2.4 eV, eco-friendliness, low cost, nontoxicity, and high stability under various conditions.…”

“…27,28 A number of experimental and computational studies have provided a relatively comprehensive understanding of the crystal morphology, physicochemical properties, synthesis methods, modification strategies, and PCE applications of CuWO 4 . 18,19,[23][24][25][26]29,30 However, the redox behavior of the low-Miller index surfaces of CuWO 4 under different environment-dependent conditions and its impact on the stability, structure, and electronic properties of the surfaces and on the crystal morphology of this material remain unknown. In this work, we have employed calculations based on the density functional theory (DFT) to study the structural and electronic properties of the bulk phase of CuWO 4 , as well as all nonpolar, stoichiometric, and symmetric terminations of its low-Miller index surfaces.…”

Influence of the Morphology of TiO2/ Au NP Nanocomposite on ITO/Glass Substrate on Their Photoelectrochemical Properties

“…Increasing the efficiency of photoelectrochemical processes, such as photocatalytic decomposition of water [1], photosynthesis [2], photocatalytic purification of water from pollutants [3] using plasmonic nanoparticles deposited on wide-gap semiconductor photoelectrodes, is a well-2 known technique for a wide range of materials, for example: [4,5], ZnO [6,7], WO3 [8], SnO2 [9], as well as more complex oxide compounds: BiVO4 [10,11], CuWO4 [12], ZnFe2O4 [13] and many others, Semiconductor materials for photoelectrochemical applications are presented and classified in more detail in detailed reviews [14,15].…”