Metallic sealants increase flux and change selectivity in supported molten-salt membranes.

Metallic sealants are widely used with high-temperature membranes. Here we show that their use in supported molten-salt membranes results in order-of-magnitude differences in CO flux and introduces O co-permeation. The 'short-circuiting' effect they introduce has important implications for the design of future experiments, and the interpretation of past work.

Separation and concentration of CO from air using a humidity-driven molten-carbonate membrane.

Separation processes are substantially more difficult when the species to be separated is highly dilute. To perform any dilute separation, thermodynamic and kinetic limitations must be overcome. Here we report a molten-carbonate membrane that can 'pump' CO from a 400 ppm input stream (representative of air) to an output stream with a higher concentration of CO, by exploiting ambient energy in the form of a humidity difference.

Exsolution of Catalytically Active Iridium Nanoparticles from Strontium Titanate.

The search for new functional materials that combine high stability and efficiency with reasonable cost and ease of synthesis is critical for their use in renewable energy applications. Specifically in catalysis, nanoparticles, with their high surface-to-volume ratio, can overcome the cost implications associated with otherwise having to use large amounts of noble metals. However, commercialized materials, that is, catalytic nanoparticles deposited on oxide supports, often suffer from loss of activity because of coarsening and carbon deposition during operation.

Tracking the evolution of a single composite particle during redox cycling for application in H production.

Composite materials consisting of metal and metal oxide phases are being researched intensively for various energy conversion applications where they are often expected to operate under redox conditions at elevated temperature. Understanding of the dynamics of composite evolution during redox cycling is still very limited, yet critical to maximising performance and increasing durability. Here we track the microstructural evolution of a single composite particle over 200 redox cycles for hydrogen production by chemical looping, using multi-length scale X-ray computed tomography.

Measuring Membrane Permeation Rates through the Optical Visualization of a Single Pore.

Membranes are a critical technology for energy-efficient separation processes. The routine method of evaluating membrane performance is a permeation measurement. However, such measurements can be limited in terms of their utility: membrane microstructure is often poorly characterized; membranes or sealants leak; and conditions in the gas phase are poorly controlled and frequently far-removed from the conditions employed in the majority of real processes.

Endogenous Nanoparticles Strain Perovskite Host Lattice Providing Oxygen Capacity and Driving Oxygen Exchange and CH Conversion to Syngas.

Particles dispersed on the surface of oxide supports have enabled a wealth of applications in electrocatalysis, photocatalysis, and heterogeneous catalysis. Dispersing nanoparticles within the bulk of oxides is, however, synthetically much more challenging and therefore less explored, but could open new dimensions to control material properties analogous to substitutional doping of ions in crystal lattices. Here we demonstrate such a concept allowing extensive, controlled growth of metallic nanoparticles, at nanoscale proximity, within a perovskite oxide lattice as well as on its surface.

Towards efficient use of noble metals via exsolution exemplified for CO oxidation.

Many catalysts and in particular automotive exhaust catalysts usually consist of noble metal nanoparticles dispersed on metal oxide supports. While highly active, such catalysts are expensive and prone to deactivation by sintering and thus alternative methods for their production are being sought to ensure more efficient use of noble metals. Exsolution has been shown to be an approach to produce confined nanoparticles, which in turn are more stable against agglomeration, and, at the same time strained, displaying enhanced activity.

Shape-persistent porous organic cage supported palladium nanoparticles as heterogeneous catalytic materials.

Porous Organic Cages (POCs) are an emerging class of self-assembling, porous materials with novel properties. They offer a key advantage over other porous materials in permitting facile solution processing and re-assembly. The combination of POCs with metal nanoparticles (NPs) unlocks applications in the area of catalysis.

Overcoming chemical equilibrium limitations using a thermodynamically reversible chemical reactor.

All real processes, be they chemical, mechanical or electrical, are thermodynamically irreversible and therefore suffer from thermodynamic losses. Here, we report the design and operation of a chemical reactor capable of approaching thermodynamically reversible operation. The reactor was employed for hydrogen production via the water-gas shift reaction, an important route to 'green' hydrogen.

Demonstration of chemistry at a point through restructuring and catalytic activation at anchored nanoparticles.

Metal nanoparticles prepared by exsolution at the surface of perovskite oxides have been recently shown to enable new dimensions in catalysis and energy conversion and storage technologies owing to their socketed, well-anchored structure. Here we show that contrary to general belief, exsolved particles do not necessarily re-dissolve back into the underlying perovskite upon oxidation. Instead, they may remain pinned to their initial locations, allowing one to subject them to further chemical transformations to alter their composition, structure and functionality dramatically, while preserving their initial spatial arrangement.

Role of the Three-Phase Boundary of the Platinum-Support Interface in Catalysis: A Model Catalyst Kinetic Study.

A series of microstructured, supported platinum (Pt) catalyst films (supported on single-crystal yttria-stabilized zirconia) and an appropriate Pt catalyst reference system (supported on single-crystal alumina) were fabricated using pulsed laser deposition and ion-beam etching. The thin films exhibit area-specific lengths of the three-phase boundary (length of three-phase boundary between the Pt, support, and gas phase divided by the superficial area of the sample) that vary over 4 orders of magnitude from 4.5 × 10 to 4.