Polymorph tungsten oxide and its sub-stoichiometric phases (WO3-x) have an extraordinarily broad range of possible photonic applications, from electrochromic layers in smart windows, to UV optical detectors, full-optical chemical sensors and photo-electro-catalytic membranes. We focus on Radio-Frequency (RF) magnetron sputtering deposition as a broadly versatile method to synthesize WO3-x in different stoichiometries and nanostructures, easily up-scalable to industrial applications. We report on WO3-x films fabricated under different recipes, which deeply differ in terms of possible applications. Optical-grade compact WO3-x films can be fabricated by non-reactive magnetron RF-sputtering deposition from a WO3 target at room temperature, followed by thermal annealing to tailor stoichiometry and structure. Films transparent in the NIR and electrically conductive can be obtained, that perform well as transparent contacts [1], but also insulating films, with the possibility to embed them into multi-layered IR resonant photonic structures for opto-chemical sensing application [2]. Nanoporous WO3-x photoelectrodes for green H2 production are obtained from metallic W target, by RF-plasma sputtering process in a diode configuration in a reactive 40% O2/Ar atmosphere. By changing the total gas pressure in the growth chamber, at same partial O2 pressure, a bilayered diode-like structure is formed, which improves photoelectron transfer and decreases the interfacial resistance (Rct), leading up to about a 30% increase in photo-electro-catalytic (PEC) performance compared to monolayers coatings and to a 93% faradaic efficiency, which is among the highest reported so far for WO3 photoanodes [3]. [1]H. Chen et al., Proceedings SPIE 12142,121421J, (2022). [2]H. Chen, et al., Optical Materials X, Vol. 12, (2021). [3]G.L. Chiarello et al., J. Mater Chem A, 5, 12977, (2017). Acknowledgements: European fund - FESR, PON Ricerca e Innovazione 2014-2020, Project BEST4U -ARS01_00519.
Functional nanostructured tungsten oxides films by RF-sputtering
Silvia Maria Pietralunga;Hao Chen;Thi Ngoc Lam Tran;Alberto Tagliaferri;
2023-01-01
Abstract
Polymorph tungsten oxide and its sub-stoichiometric phases (WO3-x) have an extraordinarily broad range of possible photonic applications, from electrochromic layers in smart windows, to UV optical detectors, full-optical chemical sensors and photo-electro-catalytic membranes. We focus on Radio-Frequency (RF) magnetron sputtering deposition as a broadly versatile method to synthesize WO3-x in different stoichiometries and nanostructures, easily up-scalable to industrial applications. We report on WO3-x films fabricated under different recipes, which deeply differ in terms of possible applications. Optical-grade compact WO3-x films can be fabricated by non-reactive magnetron RF-sputtering deposition from a WO3 target at room temperature, followed by thermal annealing to tailor stoichiometry and structure. Films transparent in the NIR and electrically conductive can be obtained, that perform well as transparent contacts [1], but also insulating films, with the possibility to embed them into multi-layered IR resonant photonic structures for opto-chemical sensing application [2]. Nanoporous WO3-x photoelectrodes for green H2 production are obtained from metallic W target, by RF-plasma sputtering process in a diode configuration in a reactive 40% O2/Ar atmosphere. By changing the total gas pressure in the growth chamber, at same partial O2 pressure, a bilayered diode-like structure is formed, which improves photoelectron transfer and decreases the interfacial resistance (Rct), leading up to about a 30% increase in photo-electro-catalytic (PEC) performance compared to monolayers coatings and to a 93% faradaic efficiency, which is among the highest reported so far for WO3 photoanodes [3]. [1]H. Chen et al., Proceedings SPIE 12142,121421J, (2022). [2]H. Chen, et al., Optical Materials X, Vol. 12, (2021). [3]G.L. Chiarello et al., J. Mater Chem A, 5, 12977, (2017). Acknowledgements: European fund - FESR, PON Ricerca e Innovazione 2014-2020, Project BEST4U -ARS01_00519.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
