VISELCAT

Visualising Electrocatalysis at the Nanoscale

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 Obiettivo del progetto (Objective)

'This proposal defines new and unique approaches to the study of electrocatalytic processes at the level of an individual nanoparticle (NP). The project marries the considerable achievements of Dr. Stanley Lai in electrocatalysis (PhD, Leiden) with that of the Electrochemistry and Interfaces Group at the University of Warwick, in high resolution electrochemistry and imaging, to create new frontier research in functional imaging of electrocatalysis. The scientific programme involves the development and application of innovative nanoscale electrochemical imaging techniques which will allow individual NPs to be produced directly on surfaces in a well-defined way, and their individual activity investigated, so that the electrocatalytic responses can be related to NP size, structure and environment. Moreover, the nanoscale methods will allow the investigation of individual NPs within an ensemble, to determine - for the first time - the range of electrocatalytic responses that operate, which is a major open question. The focus is on noble metal NPs and model fuel cell reactions, so that the results will be of immediate interest and impact to the field. The NPs will be produced on novel carbon electrode supports (graphene, single-walled carbon nanotubes, graphite and conducting diamond), in view of the considerable excitement in such materials worldwide for electrocatalysis and electroanalysis. The project will derive significant benefit from impressive facilities, equipment and infrastructure at the Host Institution, including major recent investment in state of the art high resolution microscopy and spectroscopy for materials characterisation. With considerable support and world-leading expertise from the Host group and its collaborators, this project will provide Dr. Lai with an outstanding opportunity to develop personally and professionally, by pioneering a new area of research in a new geographic location.'

Introduzione (Teaser)

Electrocatalysis plays a critical role in many new energy technologies such as fuel cells. A new EU-funded study has shed light on mechanisms of electrocatalytic activity at the level of single nanoparticles (NPs) and promises new paths to optimisation.

Descrizione progetto (Article)

Considerable interest exists worldwide in systems of noble metal NPs on nano-structured carbon electrode supports. The supports are often graphene, single-walled carbon nanotubes, graphite or conducting diamond. Effective exploitation of such electrocatalytic systems requires exquisitely detailed understanding of processes at the single-NP level.

Collaboration between expert labs in electrocatalysis and in high-resolution electrochemistry and imaging for the EU-funded project 'Visualising electrocatalysis at the nanoscale' (VISELCAT) has been quite fruitful. Success was spurred on by the scientists' development of pioneering scanning electrochemical cell microscopy (SECCM) capable of probing individual sites on electrode surfaces.

With the extremely high spatial and temporal resolution, scientists first answered many open questions regarding the electron transfer properties of the electrode support materials. In particular, groundbreaking work on highly oriented pyrolytic graphite demonstrated the need to revise current textbooks. Researchers also employed SECCM to study formation of NPs, revealing the previously underestimated role of the interaction between NPs and substrate materials. Findings are guiding new studies into electrodeposition processes.

Finally, scientists studied electrocatalytic materials with SECCM. Findings show that grain structure and surface orientation of individual grains are important to localised reactivity. Studies of single-NP reactivity within an ensemble of platinum NPs on a single carbon nanotube showed that slight variations in NP morphology change reactivity drastically.

An innovative set-up combining a very small pipette with SECCM facilitated study of the landing of individual NPs on substrate electrode materials. The low background current enabled scientists to detect minimal current signals from NPs with good time resolution. Thus, the team was able to characterise combined electrochemical and physical properties at the single-NP level for the first time.

Findings have already been published in eight peer-reviewed papers in leading scientific journals and more are in preparation. VISELCAT outcomes and techniques pave the way to optimisation of electrocatalysis through manipulation of size and catalytic activity of nanocatalysts at the single-NP level. Widespread implementation promises rapid advances and long-awaited breakthroughs in electrocatalysis for alternative energy systems, sensors, water purification and chemical synthesis.