Rational design of all-solid-state TiO/Cu/ZnO Z-scheme heterojunction via ALD-assistance for enhanced photocatalytic activity.

Poor visible light utilization and charge separation efficiency of TiO restrict its extensive application in the photocatalytic field. Herein, a specific Z-scheme TiO/Cu/ZnO heterojunction was successfully constructed by atomic layer deposition (ALD) technique and spray pyrolysis technology. Benefited from the surface plasmon resonance (SPR) effect of Cu and Z-scheme heterojunction, the visible light absorption capacity was greatly enhanced. Meanwhile, ZnO nanolayer coating, prepared by ALD technique, protects Cu element to hinder its oxidation, thus enhancing the separation efficiency of photogenerated carriers. Therefore, the photocatalytic hydrogen production performance was significant improved, exhibiting a maximum value of 342.0 µmol·g·h for the optimal B-T-0.1C-10Z (black TiO/0.1Cu/10 nm ZnO) sample without any noble-metal cocatalyst, which is higher than pure TiO (310.7 µmol·g·h, with 3 wt% Pt) synthesized by spray pyrolysis method under equal conditions. In addition, a possible mechanism for the enhanced performance was briefly discussed based on the experimental results.