Abstract: The modification of an electrode surface with an electroactive material is widely used to endow the electrode with specific molecular characteristics. These may be (electro)chemical, optical, electronic or mechanical, according to the intended application. Frequently, electrode performance deviates from expectation based on the designed interfacial architecture, motivating a better understanding of film composition, structure and dynamics and the relationships between them. Recent developments in a range of physical techniques permit them to operate in situ during film deposition, redox switching, and interaction with the bathing electrolyte, thereby revealing this information. The first half of this lecture will focus on fundamental studies of a range of electrochemically deposited films, including redox polymers (typified by polyvinylferrocene), conducting polymers (typified by polyaniline and PEDOT), and metals, together with multilayer and composite structures. Focus will be given to high frequency acoustic wave (QCM and acoustic admittance) and neutron reflectivity techniques under electrochemical control. These methods are particularly adept at quantifying the concentration and spatial distribution of solvent within the film. In contrast, many other physical techniques are blind to this colourless, electroinactive, uncharged species that exerts huge influence over mass and charge transport within the film and defines the local environment for mediated charge transfer. The second half of this lecture will show how control of redox-driven deposition of polymer and metal films can be exploited in the field of forensic science. Specifically, it will be demonstrated that spatial control of film deposition can be used to visualise latent (non-visible) fingerprints. Dependent on the nature of the deposition process – interaction with fingermark residue or bare substrate – one may highlight “ridge” or “furrow” regions of the fingermark to yield a positive or negative image. In the case of electroactive polymers, film electrochromic properties provide an additional dimension, in that the polymer colour may be reversibly adjusted to optimise visual contrast with the surface. Application of these methods to investigations of acquisitive and violent crimes will be discussed.
Bio: Robert Hillman was educated at Imperial College London and Oxford University. After post-doctoral research at Imperial College, he was appointed to a Lectureship at the University of Bristol, to the Chair of Physical Chemistry at the University of Leicester (1992), and as Dean of the Faculty of Science (2003-2009). He was Scientific Editor of Faraday Transactions and Faraday Discussions (1994-1997) and has been Editor in Chief of Electrochimica Acta since 2014. Robert has served the International Society of Electrochemistry as UK National Secretary, Secretary General, Chair of the Scientific Meetings Committee and President. His research interests are in the field of interfacial chemistry and electroactive materials, with the underlying goal of elucidating molecular explanations for observed interfacial behaviour. Since interfaces are where material transfers occur upon contact between objects, this has motivated study of the interfacial science associated with fingerprints. Recent research focuses on latent fingermark treatments involving the deposition of metals and polymers, together with analysis of the resulting surfaces and images.
