Electrocatalytic Behavior of PtCu Clusters Produced by Nanoparticle Beam Deposition

Abstract

State-of-the-art electrocatalysts for electrolyzer and fuel cell applications currently rely on platinum group metals, which are costly and subject to supply risks. In recent years, a vast collection of research has explored the possibility of reducing the Pt content in such catalysts by alloying with earth-abundant and cheap metals, enabling co-optimization of cost and activity. Here, using nanoparticle beam deposition, we explore the electrocatalytic performance of PtCu alloy clusters in the hydrogen evolution reaction (HER). Elemental compositions of the produced bimetallic clusters were shown by X-ray photoelectron spectroscopy (XPS) to range from 2 at. % to 38 at. % Pt, while high-angle annular dark field scanning transmission electron microscopy (HAADF-STEM) combined with energy dispersive X-ray (EDX) spectroscopy indicated that the predominant cluster morphologies could be characterized as either a fully mixed alloy or as a mixed core with a Cu-rich shell. In contrast with previous studies, a monotonic decrease in HER activity with increasing Cu content was observed over the composition range studied, with the current density measured at -0.3 V (vs reversible hydrogen electrode) scaling approximately linearly with Pt at. %. This trend opens up the possibility that PtCu could be used as a reference system for comparing the composition-dependent activity of other bimetallic catalysts.

Steering Hydrocarbon Selectivity in CO2 Electroreduction over Soft-Landed CuOx Nanoparticle-Functionalized Gas Diffusion Electrodes

“…CuO x ( x = 0–1) NPs were produced using the STARDUST machine (see Figure S1) under ultra-high vacuum conditions (base pressure 5 × 10 –10 mbar) using an MICS (MICS3, Oxford Applied Research Ltd., UK), details of which are given elsewhere. , …”

“…CuO x (x = 0−1) NPs were produced using the STARDUST machine 26 (see Figure S1) under ultra-high vacuum conditions (base pressure 5 × 10 −10 mbar) using an MICS (MICS3, Oxford Applied Research Ltd., UK), details of which are given elsewhere. 27,29 For the electrocatalysts synthesized and utilized in this work, we used one of the three magnetron sources available, which was loaded with a copper target (99.99% pure, 4 mm thick and 2″ diameter, Testbourne Ltd., UK). To control the oxidation state of the NPs during formation, oxygen injection in the aggregation zone was adjusted from 0 to 0.8 to 21.3 sccm, to predominantly produce Cu, Cu 2 O, and CuO NPs, respectively.…”

“…Building on the advantages of conventional physical vapor deposition methods already used in the CO 2 RR literature, − this physical deposition method includes a state-of-the-art sputter gas aggregation source (SGAS), a multiple ion cluster source (MICS) type, and a specifically tailored aggregation zone. Moreover, this technique offers a fast, reproducible, and tunable approach to deliver NPs of various metals and oxidation states. − An important advantage of this technique over the wet chemical synthesis methods is that neither organic ligands nor ion-exchange polymers are present during the synthesis of those NPs or during catalyst ink preparation, which could otherwise influence what we perceive as the intrinsic catalytic activity of the particles.…”

Spontaneous Formation of Core@shell Co@Cr Nanoparticles by Gas Phase Synthesis

“…Specifically, the NPs were grown using a multiple ion cluster source (MICS), which is an adaptation where the single magnetron is replaced by three independent magnetrons [25,26]. This modification has been shown to be very effective for the fabrication of nanoparticles with a tuneable chemical composition and structure [27]. In the current work, however, instead of using two magnetrons for the fabrication of the CoCr NPs, CoCr alloy targets were used with variable amounts of each element, and the versatility of the MICS (in particular regarding the injection of argon through different magnetrons) was exploited in order to study the formation of CoCr nanoparticles with different compositions and structures.…”

The Journal of Physical Chemistry C Virtual Special Issue on Metal Clusters, Nanoparticles, and the Physical Chemistry of Catalysis

“…Traditional model catalysts are simplified systems consisting of metal nanoparticles (NPs) of a controllable size and/or metal composition, often supported by a range of well-defined supports such as graphene or metal oxides. This VSI includes six experimental papers regarding the investigation of the heterogeneous catalysis and synthesis of novel heterogeneous catalysts: the selective hydrogenation of alkenes over Pd and Cu NPs, the stability of Pd NPs on Co 3 O 4 (111), the electrodeposition synthesis of size- and shape-controlled Cu 2 O NPs for CO 2 reduction, the beam deposition synthesis of binary PtCu NPs with various mixing modes for the hydrogen evolution reaction, and the solvothermal flow synthesis of immiscible and high-entropy alloy NPs . These studies illustrate the potential of nonprecious elements such as copper for catalytic application.…”