Elegant Z-scheme-dictated g-C3N4 enwrapped WO3 superstructures: a multifarious platform for versatile photoredox catalysis

In recent years, tungsten oxide (WO3) has attracted enormous attention owing to its unique structural and optical properties; nonetheless, slow charge transfer, sluggish kinetics of holes, and rapid electron-hole recombination markedly retard its wide-spread applications in photocatalysis. Herein, variable WO3 superstructures were constructed with their architectures finely tuned by organic acids, based on which hierarchical g-C3N4 enwrapped WO3 superstructures were constructed by an in situ self-assembly strategy. A collection of combined structural and morphological characterizations manifested that WO3 and g-C3N4 ingredients were intimately integrated forming well-defined photoredox systems. We found that these closely assembled g-C3N4/WO3 heterostructures exhibited highly efficient and versatile photoredox performances including photo-oxidation of diverse organic pollutants and selective photoreduction of a series of aromatic nitro compounds under visible light irradiation and remarkably outperformed their corresponding single WO3 and g-C3N4 counterparts by virtue of cooperative synergy. An elegant Z-scheme dominated photoredox catalytic mechanism was unambiguously determined by probing the in situ formed active species (e.g., hydroxyl radicals, superoxide radicals, and hydrogen peroxide) responsible for the significantly enhanced photoredox performances of g-C3N4/WO3 heterostructures. It is anticipated that our work could provide a straightforward paradigm to rationally fabricate WO3 superstructures and judiciously construct a large variety of Z-scheme based photocatalysts.