From Bulk to Atoms: The Influence of Particle and Cluster Size on the Hydrogen Evolution Reaction

Abstract

To investigate the influence of particle size in terms of electrocatalysis for the hydrogen evolution reaction (HER), small Ptn species with $n=1,10,13$ atoms and nanoparticles are deposited onto native titanium dioxide. These species are compared to the bare support as well as to bulk platinum with respect to the catalytic activity. Photoelectron spectroscopy showed Pt4f core-level shifts to higher binding energies with decreasing cluster size. In addition, the various species contribute significant density of states into the valence band gap of TiO2, thereby with larger particle size, the resulting band gap narrows. For nanoparticles, metal-like behaviour was already observed. Electrochemical measurements in 0.1 M H2SO4 showed the highest overall catalytic activity for bulk platinum and large Pt nanoparticles. A different assertion is obtained when the activities are related to the mass of the catalyst used, indicating that clusters with a size of about ten atoms seem to be most active. In comparison with the results from photoelectron spectroscopy regarding the electronic structure, no clear correlation to the catalytic activity was found. In terms of degradation induced due to the electrochemical treatment, the cluster samples showed no sintering effects, but instead, some detachment took place.

Size and Coverage Effects of Ni and Pt Co-Catalysts in the Photocatalytic Hydrogen Evolution from Methanol on TiO2(110)

“…The results were explained by the overall amount of accessible Pt. No clear trend in the electronic structure emerged with respect to the Pt 4f 7/2 core levels . These theoretical and experimental results explain the behavior depicted in Figure thoroughly.…”

“…No clear trend in the electronic structure emerged with respect to the Pt 4f 7/2 core levels. 42 These theoretical and experimental results explain the behavior depicted in Figure 3 thoroughly. The low or almost absent activity of Pt atoms is rationalized as follows: First, there is a low number of Pt sites compared to a cluster at equal coverage.…”

“…40 Pt 10 shows a 3D two-layer structure 41 and the parameters governing the activity are combined optimally among the cluster sizes investigated herein, as proposed by theory studies in the literature 27,39 (similar as in the work by Neuberger et al). 42 Pt >47 instead shows a high number of available Pt sites, but the particle size leads to a distinct bulklike metallic character of the majority of Pt atoms, which seems less favorable for H 2 evolution than the properties of small particles. 27,42 Furthermore, size effects are in general common for reactions involving hydrogen on metal cluster-loaded surfaces.…”

“…42 Pt >47 instead shows a high number of available Pt sites, but the particle size leads to a distinct bulklike metallic character of the majority of Pt atoms, which seems less favorable for H 2 evolution than the properties of small particles. 27,42 Furthermore, size effects are in general common for reactions involving hydrogen on metal cluster-loaded surfaces. 43,44 Since H 2 formation on Pt x /TiO 2 (110) expectedly proceeds via a reverse spillover mechanism from the support to the cluster, the system appears similar to thermal size-sensitive cluster catalysts.…”

Advances in the Electrocatalytic Hydrogen Evolution Reaction by Metal Nanoclusters‐based Materials

“…The metallic core‐lines can be detected in Pt NPs and bulk Pt, but not in deposited Pt NCs, also suggesting the strong quantum effect of cluster size on the electronic structure (Figure 3c). [ 73 ] Tsunoyama et al found that the electronic structure of Pt NCs (Pt‐n, n = ≈1–45) was closely related to their size. With good energy matching of Pt NCs with SrTiO 3 surface, Pt‐30 showed the highest HER activity per unit of Pt.…”