Synergistic Role of Self –Induced CdIn₂S₄ Nanopyramid Sacrificial Layer for Enhanced Photocatlytic Activity of TiO₂ Nanotube-Based Chalcogenide Heterostructures

Abstract

A simple treatment has been employed to obtain a novel design of the highly stable visible light responsive In2S3/CdS/TiO2 nanotubes based photocatalyst for H2 production. At first In2S3/CdS/TiO2 nanotubes was fabricated by incorporating CdS and In2S3 quantum dots (QDs) on TiO2 nanotubes (TNTs) via chemical bath disposition method. In the second step, a portion of the QDs layer (CdS and In2S3) was converted to a layer of CdIn2S4 pyramid like structure by thermal treatment of the In2S3/CdS/TNTs in Ar environment (Ar-In2S3/CdS/TNTs). The photocatalytic performance of the different heterostructure assemblies (simple or Ar treated samples) were tested. The incorporation of CdS and In2S3 QDs significantly improves the visible response showing higher value of photocurrent density and H2 production rate (0.5694 mLh-1cm-2). Furthermore, the outer layer of CdIn2S4 improve the photo-stability of In2S3/CdS/TNTs and further boost the H2 evolution rate (0.6281 mLh-1cm-2). The higher photocurrent density and the lower charge transfer resistance suggest that the structure architecture of Ar-In2S3/CdS/TNTs photo anodes provide efficient charge carrier separation and interfacial charge transport properties. Dye degradation of methylene blue using Ar-In2S3/CdS/TNTs also shows complete degradation of dye within 22 min. This time is 5 minutes less than that observed for In2S3/CdS/TNTs