The modern catalyst industry is continuously expanding and the demand for more efficient, selective and cost-effective catalysts has never been greater. In order to accelerate the intelligent design and optimisation of new, nanostructured catalysts there is a need for a deeper understanding of the interplay of various parameters including nanoparticle size, shape and distribution, in addition to complex phenomena such as surface chemistry and mass transport through porous supports.

A thorough grasp of the critical factors can only be gained through measurement of catalytic activity and chemical speciation over various length scales. Above all, the ability to characterise catalyst structure and activity an-operando (under operating conditions) is paramount for a complete understanding of catalyst behaviour.

To address the growing industrial need, our vision at NPL is to develop a toolkit of state-of-the-art catalyst characterisation techniques enabling a holistic understanding of catalyst behaviour through bulk and local structural, chemical and activity measurements.

Screening of Electrocatalyst Arrays

We are exploring the use of Scanning Electrochemical Microscopy (SECM) as a novel screening tool for electrocatalyst libraries. Microarrays of catalyst particles can be deposited onto a flat substrate with varied composition, particle size, shape or density, and the unique chemical sensitivity of SECM be used to determine the optimum parameters for a given electrocatalytic reaction within a single experiment.

Complementary Techniques

NPL also has a suite of instrumentation and expertise in a range of techniques that support the catalyst metrology theme.

Imaging:

• Atomic Force Microscopy (AFM) and conducting-AFM
• Tip Enhanced Raman Spectroscopy (TERS)
• Scanning Kelvin Probe Microscopy (SKPM)
• Scanning Electron Microscopy (SEM)

Chemical/Physical Characterisation:

• Energy Dispersive X-ray Spectroscopy (EDX)
• Electron Backscatter Diffraction (EBSD)
• Raman Spectroscopy
• X-ray/Ultraviolet Photoelectron Spectroscopy (XPS/UPS)
• Secondary Ion Mass Spectrometry (SIMS)
• Brunauer, Emmett Teller (BET) Surface Area Analysis

Applications

We are interested in a diverse range of catalytic systems, most notably:

• Liquid phase oxidation and hydrogenation reactions on metal nanoparticles (e.g. glucose and glycerol transformations)
• Fuel cell electrocatalysis (PEM, direct methanol, bio fuel cells)
• Photoelectrocatalysis

People

• Andy Wain

Publications

• Imaging size effects on the electrocatalytic activity of gold nanoparticles using scanning electrochemical microscopy
  A. J. Wain
  Electrochimica Acta, 92, pages 383-391 (2013)

Presentations

• Electrochemical Scanning Probe Microscopy for Catalyst Characterisation
  Europacat X, August 2011, Glasgow University (poster)
• Towards Nanoscale Imaging of Electrocatalytic Activity
  Gordon Conference on Catalysis, July 2010, New Hampshire, USA (poster)

External collaboration

• Gary Attard (Cardiff University)
• Lynn Gladden (University of Cambridge)