Achievement of visible-light-driven Z-scheme overall water splitting using barium-modified Ta₃N₅ as a H₂-evolving photocatalyst

摘要

Ta₃N₅ is one of the most promising photocatalyst candidates for solar water splitting, but it still remains challenging to achieve overall water splitting via Ta₃N₅-based photocatalysts regardless of whether it uses a one step or two step method. Here we will address the relatively poor photocatalytic proton reduction of Ta₃N₅ with an effort for the promotion of charge separation via barium modification. One-pot nitridation of barium nitrate-impregnated Ta₂O₅ precursor was adopted here for the synthesis of Ta₃N₅ accompanied with the creation of a Ta₃N₅/BaTaO₂N heterostructure and surface passivation. Due to the synergetic effect of the improved interfacial charge separation and the decreased defect density, the photocatalytic H₂ evolution rate of barium-modified Ta₃N₅ is effectively promoted. Encouraged by this, a visible-light-driven Z-scheme overall water splitting system was successfully constructed by using the barium-modified Ta₃N₅ as a H₂-evolving photocatalyst, together with a PtO_x/WO₃ and IO₃?/I? pair as an O₂-evolving photocatalyst and a redox mediator, respectively.