Electron Transfer Rate vs Recombination Losses in Photocatalytic H₂ Generation on Pt-Decorated CdS Nanorods

Abstract

Cadmium chalcogenide nanocrystals combined with co-catalyst nanoparticles hold promise for efficient solar to hydrogen conversion. Despite the progress, achieving high efficiency is hampered by high charge recombination rates and sample degradation. Here, we vary the decoration of platinum nanoparticles on CdS nanorods to demonstrate the important role of pathways for the photoelectrons to the co-catalyst. Contrary to expectations, the shortening of the path, by increasing the number of co-catalyst particles, increases the transfer rate but decreases the photocatalytic performance. This is because subsequent electron transfer to the acceptor is much slower; therefore, the recombination rate with the nearby holes increases. We show that with tip-decorated nanorods, the quantum yield of H2 production can reach and sustain nearly 90%, provided an efficient mechanism of mediated hole extraction is employed. The approach demonstrates that highly efficient photocatalysts may be prepared with only a minimal amount of co-catalyst and thereby suggests future pathways for solar to H2 conversion with semiconductor nanocrystals.

The Metal Type Governs Photocatalytic Reactive Oxygen Species Formation by Semiconductor‐Metal Hybrid Nanoparticles

“…The quantum efficiency of H 2 O 2 formation was significantly higher for the CdS−Au samples compared to the CdS−Pt. This result was unexpected, given the reported Pt tipped HNPs superiority toward H 2 generation . Therefore, complementary measurements of photocatalytic hydrogen generation were conducted at inert atmosphere and in the presence of Na 2 S‐9H 2 O and Na 2 SO 3 , acting as sacrificial hole scavengers (see SI for additional details).…”

Effect of Na‐Doping on Electron Decay Kinetics in SrTiO3 Photocatalyst

“…To obtain deeper understanding of the mechanism, it is essential to know how the behaviors of photoexcited electrons and holes are changed by doping. The transient absorption spectroscopy is a powerful tool to observe the photocarrier dynamics . In this work, we investigated the Na‐doping effect on photocarrier dynamics in SrTiO 3 by measuring transient absorption from visible to mid‐IR region.…”

UV‐Vis‐NIR‐Driven Plasmonic Photocatalysts with Dual‐Resonance Modes for Synergistically Enhancing H2 Generation

“…Design and synthesis of plasmonic photocatalysts through controllable wet‐chemical routes have been endowed with great promise to break through the above bottlenecks . In general, plasmonic photocatalysts are composed of noble metal nanostructures and semiconductors, in which the localized surface plasmon resonance (LSPR) of noble metal nanostructures can concentrate and amplify the incident light intensity to sensitize the photo‐physical processes of the contacting semiconductors . To date, researchers have reported the enhanced photocatalytic activities of plasmonic photocatalysts for water reduction based on the plasmon‐induced sensitization effect of either resonance energy transfer (RET) or hot electron transfer (HET) from noble metal nanostructures to semiconductors .…”