Carving the shell thickness of tungsten trioxide hollow multi-shelled structures for enhanced photocatalytic performance

Abstract

As a special hierarchical architecture, the use of the hollow multi-shelled structure (HoMS) is a new approach to greatly enhance the photocatalytic activity of materials. Precise tailoring of the shell structure in HoMSs is challenging, and its effects on the optical and electrical properties remain obscure. Herein, as a potential high-performance water oxidation photocatalyst, tungsten trioxide (WO₃) HoMSs with up to three shell numbers have been successfully fabricated. Furthermore, the accurate control of the shell thickness was realized in the range from 35 to 90 nm by optimizing the amount and distribution of tungsten ions adsorbed within carbonaceous microsphere templates. All as-synthesized WO₃ HoMSs showed excellent activities in photocatalytic water oxidation superior to WO₃ nanoparticles. Moreover, the effects of shell thickness on photocatalytic proceedings were thoroughly investigated. Although the thick-shelled (thick-3) WO₃ HoMSs have a better light-harvesting performance, thin triple-shelled (thin-3) ones expressed higher photocatalytic activity owing to the increased charge-carrier separation/transfer efficiency and larger specific areas. Consequently, the remarkable photocatalytic water oxidation activity up to 907 μmol g⁻¹ h⁻¹ with an apparent quantum efficiency of 6.3% was achieved by thin-3 WO₃ HoMSs, showing the highest values among reported WO₃ photocatalysts. Moreover, the mechanism clarification for modulating the shell thickness and the effect of the shell thickness on performance will be a valuable reference for further designing and synthesizing new nanostructures for highly efficient solar energy conversion.