Fabrication of direct Z-scheme Ta3N5-WO2.72 film heterojunction photocatalyst for enhanced hydrogen evolution

A combination of atomic layer deposition (ALD) and sol-gel techniques was applied to fabricate a direct Z-scheme Ta3N5-WO2.72 heterojunction film photocatalyst for improved H-2 generation. The Ta3N5 was deposited by ALD on WO2.72 sol coated on Si wafer. Ta3N5 film coated onbare Si wafer showed 13.2 mu mol/g of H-2 generation after 6h under irradiation by a 150W Xe lamp with a cut-off filter (lambda > 420 nm). In comparison, the direct Z-scheme Ta3N5-WO2.72 heterojunction film demonstrated a more than two-fold increase in H-2 production (31.9 mu mol/g). The efficiency of the Ta3N5-WO2.72 heterojunction film further increased to 46.4 mu mol/g upon coating with Pt nanoparticles by ALD. Additionally, the direct Z-scheme Ta3N5-WO2.72 heterojunction film generated 18 times more H-2 than a Ta3N5-WO3 liquid-state (using Nal as the shuttle redox mediator) Z-scheme system prepared by mixing Ta3N5 and WO3 powders. The H-2 generation of the direct Z-scheme Ta3N5-WO2.72 heterojunction film coated with Pt nanoparticles further increased to 3072.5 mu mol/g without the 420 nm cut-off filter. (C) 2016 Elsevier B.V. All rights reserved.