“Suspended” Pt nanoparticles over TiO₂ nanotubes for enhanced photocatalytic H₂ evolution

Abstract

In the present work we introduce a technique to form a photocatalyst based on Pt nanoparticles suspended over the mouth of anodic TiO2 nanotubes. These structures are obtained by decorating the top end of highly ordered TiO2 nanotubes with a web of TiO2 nanofibrils, followed by sputter deposition of a minimum amount of Pt. A subsequent thermal dewetting step forms 3-6 nm-sized Pt nanoparticles along the nanofibrils. These structures, when compared to conventional Pt decoration techniques of TiO2 nanotubes, show strongly enhanced photocatalytic H2 evolution efficiency.

Efficient Photocatalytic H2 Evolution: Controlled Dewetting–Dealloying to Fabricate Site‐Selective High‐Activity Nanoporous Au Particles on Highly Ordered TiO2 Nanotube Arrays

“…This may be attributed to the fact that porous gold nanoparticles in "crown" position are more accessible to the liquid phase (diffusion) and the interface contact with reactants is thus maximized, while shadowing is not substantially affecting the performance. [12] In other words, a configuration of Au/TiO 2 nanotubes with the noble metal nanoparticles in crown position, which we could not obtain by other previously explored strategies, [14] is seemingly an optimized solution for UV-light driven H 2 generation.…”

“…In every case and well in line with some previous reports, we observed for all systems that the amount of photocatalytically evolved H 2 linearly increased over the irradiation time (the results discussed below are thus given as the total amount of H 2 evolved after a 5h-long photocatalytic run). [12,15,17] In order to investigate the influence of the Au loading, we fixed the Ag/Au ratio to 2:1 ( Figure 4(b)), and deposited various thicknesses of the metal layers -in line with theory on dewetting mechanisms, the thickness of the metal layer, i.e., the amount, strongly influences dimension and distribution of the dewetted particles (see Figure S4 and ESI for more details). [18] For the configurations (and loadings) where mixed ground/crown or a full ground position was established, a clearly lower H 2 evolution efficiency was obtained compared to only crown position.…”

Self-organized Anodic TiO2 Nanotubes: Functionalities and Applications Due to a Secondary Material

“…3.18d. By the subsequent dewetting they finally achieved decoration of the fibrils by Pt nanoparticles, used similarly as in the first report for the H 2 production [77]. In their next follow up paper [78], they demonstrated use of the porous structure for templating of a range of metals, including Au, Pt, AuPd, Pd and polystyrene.…”

“…3.18 SEM a top view and cross-sectional (b) images of extremely ordered TiO 2 porous structure by tailored anodization in hot H 3 PO 4 /HF electrolytes, c Au metal replica by sputtering the ideal filling of the TiO 2 pores, modified from [28]; d SEM image of the same structure as in (b) but with TiO 2 nanofibrils with decorated Pt nanoparticles by dewetting of previously sputtered thin Pt film, modified from [77] this system as photocatalyst to produce hydrogen from aqueous ethanolic solutions. In their follow up paper [77], they first modified the as-prepared pores by NaOH to create TiO 2 nanofibrils onto which they subsequently deposited very thin Pt layer (1 nm), as shown in Fig. 3.18d.…”

Efficient Photocatalytic Hydrogen Evolution by Iron Platinum Loaded Reduced Graphene Oxide

“…Up to now, numerous metal-based photocatalysts have been discovered as catalysts for this reaction 11,12 , but they are ultimately of low efficiency, high cost, and low abundance 13,14 . Several strategies have been employed to improve the photocatalytic performance of metallic photocatalysts, for example, textural design 15,16 , coupling with other metal photocatalysts 17,18 , etc. In particular, great interest has been devoted to linking carbon nanomaterials 19 .…”