Electrochemical Nuclear Magnetic Resonance cell – EC NMR 5 mm dia. probe
Nuclear magnetic resonance (NMR) spectroscopy combined with electrochemical (EC) methods, provides crucial insight into the processes at and near the electrode surface at the molecular level. This technique allows to acquire NMR spectra while controlling an electrical potential at working electrode, to characterize the electrochemically generated species.
The EC NMR cell consists of three major parts: a) 5 mm OD glass NMR tube with tube stopper, b) electrochemical cell with the electrode assembly, and c) cell holder of various dimensions depending on the NMR system.
The electrode assembly which is an inset for standard 5 mm OD NMR tube may be configured in various ways: a) with only WE in NMR detection area, b) with WE below while CE and RE above the NMR detection area, and c) with WE, CE and RE above the NMR detection area. Electrode leads inside the cell are insulated with PTFE tubes to avoid short circuit. The selection of materials for electrodes may be changed on request.
The EC NMR cell ensures oxygen free conditions in both aqueous and organic electrolytes. The chokes integrated in the electrical leads reduce the encountered interference between the NMR spectrometer and the potentiostat.
The EC NMR cell elements are constructed with the following materials: a) Metallic - Tantalum, Silver, Platinum, Copper, Aluminum, Gold, Brass, and b) Non-metallic - PTFE, PEEK, FEP, FFKM, NMR glass (tube), Nylon, and PVC. The EC cell compartment is made of materials that are inert to the sample (glass and PEEK). It well fits aqueous (FKM O-Rings) and organic solvent (FFKM O-Rings) electrolyte requirements. The construction is gas-tight and can be used when the removal and exclusion of contaminants such as oxygen and water is required by bubbling of an inert gas through the electrolyte.
In-situ Electrochemical Nuclear Magnetic Resonance is a powerful method for structural analysis and dynamic investigation of chemical reaction systems. It provides an information about the concentration of reactants and products in real-time. It may also be used to study magnetoelectrolysis phenomenon (turbulence-inducing effect of the magnetic field on electrochemical reactions).
A selection of WE (active film and current collector) influences the magnetic field homogeneity and signal to noise ratio and consequently affects the spectral quality. Typically used WEs are: carbon fibers, carbon woven and non-woven membranes, thin metal films, foils, meshes and wires (Au, Cu, Al), ITO films on plastic substrates, etc.
The tube should be filled with an electrolyte up to 50 mm of the height. Insertion of electrodes will slightly increase the liquid level. The electrolyte may be bubbled prior to the experiment, through gas inlet, while having the gas outlet open (or secured with one-way valve). The bubbling of gas through the solution must be stopped prior to experiment.
An assembled cell is placed inside the spinner turbine (not included in the cell) where the position of the electrodes in relation to detection area is set. The tube stopper is used to additionally immobilize the tube, due to the subnational weight of the whole setup.
WARNING: The spinning mode is not allowed because it would mess up the connection and may also damage the NMR system. The EC NMR cell has to be installed manually without the assistance of the automatic sample changer.
The pictures presented on this product page show the holder model compatible with Bruker Ascend 500 NMR system. The cell is also compatible with other NMR models and brands. However, the holder dimensions should be arranged before the product dispatch. For troubleshooting instruction see the redox.me blog post.
NMR tube outer diameter: 5 mm
CE material: 500 mm long, 0.6 mm dia. Platinum wire
RE material: 0.4 mm dia. recrystallized Silver wire
WE lead: 0.4 mm dia. Tantalum wire clip
1 x lid
1 x chamber
1 x tube fixture
1 x tube stopper
1 x set of screws
5 x Precision Sample NMR Tube – Wilmad 505-PS-7, 5 mm OD, 0.38 mm wall, 7’’ long, class A
1 x Metal wire auxiliary electrode 175HX25 0.6/500 mm, Platinum
1 x Pseudo-Reference Electrode PRW 0.4/220 mm, Silver/PTFE
5 x Tantalum wire clip 0.6/220 mm
1 x customized cell holder, Aluminum
1 x customized 3 wire electrical lead with RF chokes
1 x set of PEFE tubes for gas inlet/outlet