Electrochemical NMR cell

Summary. We describe the design, constroction, and operation of two types of nuclear magnetic resonance (NMR) sample probes for use in electrocatalysis/surface NMR studies. The first is an electrochemical NMR cell, which permits observation of NMR signals of surface-adsorbed species under external potential control. This cell also permits conventional voltammograms to be recorded fi-om the actual NMR sample. The second or mini-cell has a long, thin sample region and better sensitivity than the electrochemical NMR cell, but is not capable of voltammetry. Spectra have been obtained for CO, CN and adsorbed on polycrystalline platinum black, as a fimction of applied potential, demonstrating the feasibility of multinuclear NMR studies at electrified interfaces. 

Our recent improvements in instrumentation are centered around the new electrochemical NMR cell (Fig. 1). 

Fig. 1. (A) Diagram of electrochemical NMR cell A, the counter electrode, encased in a 14/20 male joint. B, Upper electrolyte reservoir C, Sample chamber for Pt black D, working electrode lead connected to R gauze in sample chamber E, vacuum/waste Luer connection F, Reference electrode Luer conneetion. (B) The assembled electrochemical NMR probehead.

Both the electrochemical NMR cell and the mini-cell require a custom-built probe (Fig. 

Using the electrochemical NMR cell, the potential dependence of the frequency shift for CO and CN on platinum black is currently being investigated. Data such as these will then be used as a basis for modeling how chemical shifts and electronic structure may be influenced by an applied electric field. 

Studies using the present electrochemical NMR cell designs are practical for many... 

Lu C, Rice C, Masel Ml, Babu PK, Waszczuk P, Kim HS, Oldfield E, Wieckowski A. 2002. UHV, electrochemical NMR, and electrochemical studies of platinum/ruthenium fuel cell catalysts. J Phys Chem B 106 9581-9589. 

P.K. Bahu, J.H. Chung, E. Oldfield, A. Wieckowski, CO surface diffusion on platinum fuel cell catalysts by electrochemical NMR, Electrochim. Acta 53 (2008) 6672-6679. 

The change in the electronic properties of Ru particles upon modification with Se was investigated recently by electrochemical nuclear magnetic resonance (EC-NMR) and XPS [28]. In this work, it was established for the first time that Se, which is a p-type semiconductor in elemental form, becomes metallic when interacting with Ru, due to charge transfer from Ru to Se. On the basis of this and previous results, the authors emphasized that the combination of two or more elements to induce electronic alterations on a major catalytic component, as exemplified by Se addition on Ru, is quite a promising method to design stable and potent fuel cell electrocatalysts. 

One possible strategy in the development of low-overpotential methods for the electroreduction of C02 is to employ a catalyst in solution in the electrochemical cell, A few systems are known that employ homogeneous catalysts and these are based primarily on transition metal complexes. A particularly efficient catalyst is (Bipy)Re[CO]3Cl, where Bipy is 2,2 bipyridine, which was first reported as such by Hawecker et al. in 1983. In fact, this first report concerned the photochemical reduction of C02 to CO. However, they reasoned correctly that the complex should also be capable of catalysing the electrochemical reduction reaction. In 1984, the same authors reported that (Bipy)Re[C013CI catalysed the reduction of C02 to CO in DMF/water/ tetraalkylammonium chloride or perchlorate with an average current efficiency of >90% at —1.25 V vs. NHE (c. —1.5V vs. SCE). The product analysis was performed by gas chromatography and 13C nmr and showed no other products. 

BASIL CIS CV CVD DSSC ECALE EC-STM EDX, EDS, EDAX EIS EMF EQCM FAB MS FFG-NMR Biphasic Acid Scavenging Utilizing Ionic Liquids Copper-indium-selenide Cyclic Voltammetry Chemical Vapor Deposition Dye Sensitized Solar Cell Electrochemical Atomic Layer Epitaxy Electrochemical in situ scanning tunnelling microscopy Energy Dispersive X-ray analysis Electrochemical Impedance Spectroscopy Electromotive Force Electrochemical Quarz Crystal Microbalance Fast atom bombardment mass spectroscopy Fixed Field Gradient Nuclear Magnetic Resonance... 

There are reports on the use of both NMR and ESR for the study of electrode materials [83-85] and bulk products of electrochemical processes [86,87], For instance, 7Li NMR may be found to be very useful for the study of Li intercalation into carbonaceous materials [88], A major advantage of these techniques is that they are applied in situ. The electrochemical cell is, in fact, an NMR tube in which the studied electrode is mounted so that it can be placed within the magnet s cavity. While NMR provides information on the environment of the element studied, within the electrode measured, ESR provides information on the formation and stability of radical ions when formed during the course of an electrochemical process. 

Nuclear magnetic resonance (NMR) spectroscopy — Nuclear magnetic resonance (NMR) spectroscopy of atoms having a nonzero spin (like, e.g., H, 13C) is an extremely powerful tool in structural investigations in organic and inorganic chemistry. Beyond structural studies atoms observable with NMR can also be used as probes of their environment. Thus NMR may be employed for in situ spectroelectrochemical studies [i]. Cell designs for in situ NMR spectroscopy with electrochemical cells are scant. Because of the low sensi-... 

---