Activation and Deactivation of the Photocatalytic Hydrogen Production Activity of Pt‐Tipped CdSe/CdS Nanorods

Abstract Hybrid semiconductor‐metal nanostructures are promising candidates for converting light into chemical energy by photocatalytic hydrogen production. However, many photocatalysts are prone to photocorrosion which limits their long‐term stability and thus their long‐term functionality needed for commercial applications. This study provides an in‐depth insight into the photocorrosion‐induced changes altering the chemical and photophysical properties of platinized CdSe‐seeded CdS nanorods (CdSe/CdS/Pt) during the photocatalytic hydrogen production from aqueous ethanol solutions at very high pH values. Using a combination of mass spectrometry, NMR spectroscopy, electron microscopy, with in situ absorption and fluorescence spectroscopy, it is shown that the ligand shell consisting of 11‐MUA does not directly contribute to the generated hydrogen, although it is gradually degraded by present OH ^• radicals. Instead, the degradation of the ligand shell first leads to higher reactivity over time and finally to aggregation of the photocatalyst once a sweet spot is crossed. The inorganic CdSe/CdS/Pt particles are then reacting with OH ^• radicals to break apart into different pieces to transform into polymeric sulphur and Cd ²⁺ . This shows that the presence of OH ^• radicals can be very beneficial as an effective hole scavenger but can also lead to degradation of the whole colloidal nanostructure at longer reaction times.