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.