Grain-growth mediated hydrogen sorption kinetics and compensation effect in single Pd nanoparticles

Abstract

Grains constitute the building blocks of polycrystalline materials and their boundaries determine bulk physical properties like electrical conductivity, diffusivity and ductility. However, the structure and evolution of grains in nanostructured materials and the role of grain boundaries in reaction or phase transformation kinetics are poorly understood, despite likely importance in catalysis, batteries and hydrogen energy technology applications. Here we report an investigation of the kinetics of (de)hydriding phase transformations in individual Pd nanoparticles. We find dramatic evolution of single particle grain morphology upon cyclic exposure to hydrogen, which we identify as the reason for the observed rapidly slowing sorption kinetics, and as the origin of the observed kinetic compensation effect. These results shed light on the impact of grain growth on kinetic processes occurring inside nanoparticles, and provide mechanistic insight in the observed kinetic compensation effect.

Optical Hydrogen Nanothermometry of Plasmonic Nanoparticles under Illumination

“…To demonstrate the hydrogen nanothermometry concept, we nanofabricated quasi-random arrays of Pd disks with a nominal diameter of 140 nm and a height of 25 nm on a 9 × 9 mm 2 glass substrate using hole-mask-colloidal lithography, 62 followed by a thermal annealing step to induce particle recrystallization and ensure a reproducible response upon subsequent hydrogenation ( Figure 2 a; see also Methods ). 63 The annealed sample was then placed in a quartz-tube plug-flow reactor inside a glass pocket holder with optical access 64 and contacted with a spring-loaded thermocouple on its edge to monitor its global temperature ( Figure S1 ). To enable measurements of optical isotherms at constant reactor temperature at different levels of illumination (and thus different local sample temperatures), the reactor was heated with constant power via a resistive heating coil; that is, no feed-back loop for temperature control was used.…”

“…Prior to the first isotherm measurement the samples were annealed at 500 °C in 4% H 2 with a flow of 200 mL/min for 12 h to induce grain growth and thereby induce reproducible response upon H 2 exposure. 63 Scanning Electron Microscopy. The SEM images were recorded with the in-lens system of a Zeiss Supra 55 VP.…”

“…H 2 (4% ± 2 rel % diluted in Ar carrier gas) and Ar carrier gas (99.9999% purity) were used. Prior to the first isotherm measurement the samples were annealed at 500 °C in 4% H 2 with a flow of 200 mL/min for 12 h to induce grain growth and thereby induce reproducible response upon H 2 exposure …”

Inverse designed plasmonic metasurface with parts per billion optical hydrogen detection

“…Prior to measurements, all sensors were exposed to multiple cycles (>20) of pure H 2 (1 bar) and vacuum at room temperature to stabilize the hydrogen-induced microstructural changes in the nanoparticles 67 . The sensors’ LoD determination was performed in a custom-made reactor chamber (effective volume ca.…”

Synthesis and Study of Palladium Mono- and Bimetallic (with Ag and Pt) Nanoparticles in Catalytic and Membrane Hydrogen Processes

“…Many articles [ 13 , 14 , 15 , 16 , 17 ] confirm the presence of structural sensitivity in a variety of nanomaterials. This means that the size, shape, spatial distribution, and composition of nanoparticles, especially noble metal ones, are key parameters for tuning their activity and reactivity [ 18 , 19 , 20 , 21 , 22 ].…”