Tuning the Surface Electrochemistry by Strained Epitaxial Pt Thin Film Model Electrodes Prepared by Pulsed Laser Deposition

Abstract

toward different reactions such as methanol [ 1 ] or ethanol [ 2,3 ] oxidation, hydrogen oxidation, [ 4 ] and oxygen reduction reaction. [ 5,6 ] However, the slow kinetics of some of these reactions results in great losses concerning the respective energy conversion effi ciencies. This drawback, together with Pt dissolution phenomena requires a large amount of Pt at the electrode. The accompanying cost and scarcity of Pt represent the prime impediments toward a broad practical application of fuel cells. Electrode interface properties play a decisive role in controlling the electrocatalytic performance. [ 7 ] Since Pt-based materials are to date the best electrocatalysts for these reactions, [ 8 ] extensive research has been dedicated to develop novel Pt-based catalyst architectures with a specifi cally tailored electrode-electrolyte interface. In recent years it has been demonstrated that strain on metal surfaces can have a signifi cant impact on the adsorbate's binding energies and on the activation energy barrier for adsorption processes. [ 9 ] In this regard, core-shell nanoparticles (NPs), where an outer monolayer (ML) of Pt is supported on another metal [ 10,11 ] or on Pt-alloy NPs [ 12 ] have been designed. The strain in these systems is generated due to the difference in lattice constant between the outer ML and the core of the NP. When the top ML adapts its crystal lattice to the underlying core lattice, depending on the sign of the lattice misfi t the ensuing stress induces tensile or compressive lattice distortions (strain).In general, surface strain can also be generated by deposition of ultrathin (few ML thick) metal fi lms on substrates. [ 3,[13][14][15] One strategy utilizes the galvanic displacement of an underpotentially deposited (UPD) copper-ML by Pt on various substrates. [ 3,13 ] The strained Pt MLs reveal a substantial increase in activity toward methanol and ethanol electrooxidation. The electrochemical behavior of ultrathin Pt fi lms of varying thickness evaporated on Ru(0001) substrates was also examined by cyclic voltammetry (CV). [ 16 ] It was found that the reversible adsorption of H and OH strongly depends on the Pt thickness and in turn the extent of the strain induced in the Pt surface. Recently, another approach involved growing ultrathin Pt fi lms on W(111) substrates with varying Pt thickness of 2.2, 3.3, and A novel approach for tailoring strained Pt model electrocatalysts using pulsed laser deposition is presented. The physical properties of Pt fi lms grown on single-crystalline (100)-and (111)-oriented strontium titanate depend signifi cantly on the various deposition parameters (e.g., fl uence, temperature, background atmosphere, postannealing, and number of process steps), as revealed by scanning electron microscopy and X-ray studies. By properly selecting the deposition conditions, thin, epitaxial, and strained (100)-and (111)-oriented Pt fi lms suitable as model electrodes can be prepared. Cyclic voltammetry measurements indicate that the strain in the Pt fi lms changes sig...

Benchmarking Pt and Pt-lanthanide sputtered thin films for oxygen electroreduction: fabrication and rotating disk electrode measurements

“…Morimoto and co-workers showed that atomic layer deposition (ALD) can be successfully employed to produce Pt electrodes on SiO2 substrates for testing on MEAs [56]. More recently, Schmidt and co-workers investigated the influence of the growth mechanism on the surface structure of thin films fabricated by pulsed laser deposition (PLD), demonstrating that strain can enhance the ORR activity [57,58]. Kim and co-workers fabricated nanoparticulate thin films of alloys of Pt-late transition metals together with Pt-Y and Pt-La for ORR using magnetron sputtering [59][60][61].…”

Enhanced Methanol Oxidation on Strained Pt Films

“…They observed a strain effect on the adsorption of OH – species and the oxidation of CO ads . Similarly, model Pt thin film electrodes were prepared by Temmel et al using a pulsed laser deposition (PLD) method to investigate CO oxidation on strained Pt surfaces. Single-crystal (100)- and (111)-oriented strontium titanate (STO) substrates were used for epitaxial deposition.…”

Laser irradiation construction of nanomaterials toward electrochemical energy storage and conversion: Ongoing progresses and challenges

“…The optimized hierarchical oxygen-incorporated amorphous MoS x electrocatalyst delivered extremely small overpotentials (170 mV at À100 mA cm À2 ), superb kinetics Apart from these common laser-induced syntheses of electrocatalysts, atomic epitaxial growth on an appropriate substrate has also been designed and developed. 175,176 Chung's group reported the influence of both tensile and compressive strains on the generation behaviors of Ruddlesden-Popper (RP) two-dimensional planar faults in (001) epitaxial LaNiO 3 thin films by using two distinct substrates of LaAlO 3 and SrTiO 3 , as illustrated in Figure 11(F,G). 177 The number of RP faults for SrTiO 3 substrate is about a two times higher than that for the case using the LaAlO 3 , indicating that the RP-fault formation can be improved for the LaNiO 3 film under a tensile strain field.…”