Carbon-based counter electrodes

Fig. 4. (A) Photograph of screen-printed gold and carbon electrode with the three-electrode system including a carbon-based counter electrode and Ag/AgCI-based inner reference electrode. (B) Photograph of a typical electrochemical setup with a computer-controlled potentiostat connected to a screen-printed electrode (SPE).

Carbon-Based Counter Electrodes Whilst carbon is a cheaper, abundant alternative to Pt, the catalytic activity is far lower, resulting in a lower efficiency when used in the DSSC. ° However, from a manufacturing perspective, carbon electrodes are favourable since they do not require the heating step that is necessary for adhesion of Pt to the substrate and... 

A new approach to improve the performance of solar devices using natural pigments is to employ carbon nanotube (CNT)-based counter-electrodes. As previously reported, the excited dye transfers an electron to Ti02 and so it acquires a positive charge. Then, the cationic molecule subtracts an electron from the counterelectrode which is transported by the electrolyte. This reaction is usually catalyzed by means of conductive and electrocatalytically active species for triiodide reduction of carbon coatings. CNTs have a high superficial area, which represents a very... 

Further, due to its unique 2D flexible structure and extremely high carrier mobility, graphene has proven to be an attractive material as well as good promoter for electron transportation. In DSSCs, the expensive Pt-based counter electrode has to be replaced by low-cost materials and highly conductive carbon-based materials are promising candidates. Recently researchers have reported that the performance of graphene functionalized... 

Murakami TN, Ito S, Wang Q, Nazeeruddin MK, Bessho T, Cestir I, liska P, Humphry-Baker R, Comte P, Pechy P, Gratzel M (2006) Highly effident dye-sensitized solar cells based on carbon black counter electrodes. J Electrochem Soc 153(12) A2255-A2261. doi 10.1149/1.2358087... 

This method in some ways resembles the technique for ASV [321,322]. The analytical device is based on a three-electrode system (1) a glassy carbon electrode, which serves as a cathode (2) a saturated calomel electrode (SCE), which is the reference electrode and (3) a platinum counter-electrode during electrolysis. 

NADH can be readily monitored electrochemically, and can be used as a simple and effective method to monitor metal ion concentrations. Such an approach has been recently utilised by Rodriguez et al. [149] for an SPCE-based biosensor for the amperometric detection of Hg2+, Cu2+, Cd2+, Zn+ and Pb2+. Devices used in this study were printed onto 250 pm thick polyester sheet. The working electrode (planar area 0.16 cm2) was fabricated from a commercially available carbon powder containing 5% rhodium plus promoters, which was made into a screen-printable paste by mixing 1 4 in 2.5% (w/v) hydroxyethyl cellulose in water. The reference electrode ink contained 15% silver chloride in silver paste. The counter electrode and basal tracks were fabricated... 

Sodium phosphate monobasic [S 9638], sodium phosphate dibasic [S 0876], sodium chloride [S 7653], acetylcholinesterase from Elect-rophorus electricus (Type V-S) [C 2888], potassium chloride [P 3911], 1,2-diaminobenzenedihydrochloride [P 1526], paraoxon (o,o-diethyl o-4-nitrophenyl phosphate) [D 9286], ferrocene carboxylic acid [106887], aniline [A 9880] and acetylthiocholine chloride [A 5751] were purchased from the Sigma Chemical Company (Dorset, UK). Screen-printed transducers were purchased from Gwent Electronic Materials Ltd. (Gwent, Wales, UK). These electrode assemblies comprised a working electrode based on carbon ink doped with cobalt phthalocya-nine, an on board reference electrode (Ag/AgCl) and counter electrode (platinum) (see Fig. 24.1). 

The electrochemical cells used are three electrode strips, based on a carbon working electrode, a carbon counter electrode and a silver pseudo-reference electrode [1],... 

Dimensionally Stable Anodes— These anodes are composed of a base metal such as titanium, coated with a precious metal oxide (e.g., ruthenium dioxide). Such anodes can be used instead of Pt or carbon for oxygen evolution counter electrodes in an organic electrosynthesis. They have also found some applications for organic oxidation reactions [61]. 

As a critical component of the DSSC, counter electrode is also a key to the flexibility of the device. Some flexible conductive materials, such as conducting polymers, carbon-based nanomaterials and their composites have been employed as flexible counter electrodes to replace the Pt electrode in the fabrication of flexible DSSCs. For instance, after coating with conducting polymer PEDOT, a flexible counter electrode was developed with low sheet resistance and served as an ideal candidate in replacement of the conventional Pt counter electrode (Fig. 9.1B) (Mozer et al., 2010). 

Aitola, K., Borghei, M., Kaskela, A., Kemppainen, E., Nasibulin, A.G., Kauppinen, E.I., Lund, P.D., Ruiz,V., Halme, 2012. Flexible metal-free counter electrode for dye solar celk based on conductive polymer and carbon nanotubes. J. Electroanal. Chem. 683,70-74. 

Arbab, A.A., Sun, K.C., Sahito, lA., Qadir, M.B., Jeong, S.H., 2015. Multiwalled carbon nanotube coated polyester fabric as textile based flexible counter electrode for dye sensitized solar cell. Phys. Chem. Chem. Phys. 17,12957-12969. 

Figure 5 (a) Disposable sensor element based on a screen-printed carbon electrode [33]. The MIP was coated onto the carbon working electrode (middle) which is surrounded by a carbon counter electrode (smaller arc) and an Ag/AgCl reference electrode (larger arc) (b) differential pulse voltammetric scan after incubation of the electrode in lOmM of the electroactive probe 2,5-dihydroxyphenylacetic acid in the presence of two different concentration of the competing analyte 2,4-D. 

S. Sigdel, et al, Dye-sensitized solar cells based on spray-coated carbon nano-fiber/TiOj nanoparticle composite counter electrodes. Journal of Materials Chemistry A, 2014. 2(29) p. 11448-11453. 

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