Voltammetric in-situ profiling

Tercier, M.-L., Buffle, J. and Graziottin, F. (1998) A novel voltammetric in-situ profiling system for continuous real-time monitoring of trace elements in natural waters. Electroanalysis, 10, 355-363. 

Tercier-Waeber, M.-L., Belmont-Hebert, C. and Buffle, J. (1998) Real-time continuous Mn(II) monitoring in lakes using a novel voltammetric in situ profiling system. Environ. Sci. Technol, 32, 1515-1521. 

Braungardt CB, Achterberg EP, Axelsson B, Buffle J, Graziottin F, Howell KA et al (2009) Analysis of dissolved metal fractions in coastal waters an inter-comparison of five voltammetric in situ profiling (VIP) systems. Mar Chem 114 47-55... 

We have reviewed the family of dealloyed Pt-based nanoparticle electrocatalysts for the electroreduction of oxygen at PEMFC cathodes, which were synthesized by selective dissolution of less-noble atoms from Pt alloy nanoparticle precursors. The dealloyed PtCua catalyst showed a promising improvement factor of 4-6 times on the Pt-mass ORR activity compared to a state-of-the-art Pt catalyst. The highly active dealloyed Pt catalysts can be implemented inside a realistic MEA of PEMFCs, where an in situ voltammetric dealloying procedure was used to constructed catalytically active nanoparticles. The core-shell structural character of the dealloyed nanoparticles was cmifirmed by advanced STEM and elemental line profile analysis. The lattice-contracted transition-metal-rich core resulted in a compressive lattice strain in the Pt-rich shell, which, in turn, favorably modified the chemisorption energies and resulted in improved ORR kinetics. 

Since their first publication in 1980 (7), the voltammetric profiles of clean, ordered platinum single crystals have been a subject of controversy, especially in the case of Pt(l 11). At first, the main discussion point was related to the surface state of the sample after the flame treatment. Did the obtained voltammetric profile correspond to the clean, atomically ordered surface expected for the crystallographic basal plane or was the ordered surface obtained only after some voltammetric cycles involving oxygen adsorption (2) The answer to these questions was gotten by means of well-established Surface Science techniques, such as ex-situ LEED, either with clean samples (J) or with those prepared by I-CO replacement (4), and by in-situ STM (5). These results proved that the flame treatment and subsequent water protection led to clean, well-ordered Pt(lll) surfaces, which gave a voltammetric response never observed before 1980. 

Fig. 23.12 Standard version of the VIP system for in-situ monitoring and profiling, (a) Voltammetric probe, (b) multiparameter probe, and (c) online O2 removal system. Reproduced...

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