Size-Selected Subnanometer Cluster Catalysts on Semiconductor Nanocrystal Films for Atomic Scale Insight into Photocatalysis

Abstract

We introduce size-selected subnanometer cluster catalysts deposited on thin films of colloidal semiconductor nanocrystals as a novel platform to obtain atomic scale insight into photocatalytic generation of solar fuels. Using Pt-cluster-decorated CdS nanorod films for photocatalytic hydrogen generation as an example, we determine the minimum amount of catalyst necessary to obtain maximum quantum efficiency of hydrogen generation. Further, we provide evidence for tuning photocatalytic activities by precisely controlling the cluster catalyst size.

Catalysis with Supported Size-selected Pt Clusters

“…10 The threshold for saturation is expected for distances between the Pt clusters comparable to the spatial extent of the electronic wave functions. In the present case, this allows for estimating this distance to 5 to 8 nm [220]. For even larger coverages, this effect becomes more severe as the comparison to colloidal systems indicated maximum QE (1.34%) observed for a colloidal CdS/Pt NR photocatalyst from the same NR batch under the same experimental conditions with higher catalyst coverage (∼ 300 cluster /NR) shows.…”

“…This modeled QE takes into account that only the uppermost layer of CdS nano rods is decorated with Pt clusters and is thus photo catalytically active [313,220]. 40 Corresponding TEM samples were prepared by means of drop casting NR solution onto TEM grids, since spin coating is not feasible.…”

“…Pt(OH) x ) is present. Further it can be stated, that with the measured BE shifts a full oxidation of the clusters after transfer to ambient conditions can be excluded and thus might be an explanation for the observed persisting reactivity after transfer [220,38].…”

First-principles thermodynamic screening approach to photo-catalytic water splitting with co-catalysts

“…The actual DFT calculations for the co-catalyst are then simply performed at single-crystal surface models when aiming to assess the catalytic function of dominant facets of larger nanoparticles, or at clusters in the non-scalable size regime when aiming to assess potential nano-catalytic behavior. As a showcase we here present both avenues and for Au, which has shown much promise not only for its general nano-catalytic properties [18][19][20][21] , but also in the water splitting context 7,8,22 . Specifically, we compute the water oxidation pathway at (unreconstructed) Au(111) and at 13 clusters consisting of between 2 and 55 Au atoms.…”

Aqueous synthesis of CdS and CdSe/CdS tetrapods for photocatalytic hydrogen generation

“…[11][12][13] Very recently, they also started to gain an increasing attention as components of photocatalytic systems for hydrogen generation from water. [14][15][16][17][18][19][20][21][22][23][24][25][26][27][28] These studies commonly combine colloidal semiconductor nanocrystals possessing superior light harvesting properties--often of rod-like or tetrapod-like shapes--with a metal-based co-catalyst possessing catalytic properties, such as platinum, palladium, or nickel. 15,29,30 For the chosen semiconductor nanocrystals, it is important to consider a suitable band gap as well as the absolute position of the conduction and valence band minima/maxima, 31,32 in order to absorb as much light as possible from the solar spectrum, and at the same time to match the reduction and oxidation potentials of water.…”