(An) infrared thin-layer cell fabricated in a silicon micromachined structure for in situ FT-IR monitoring of electrochemical reaction

Abstract

A thin-layer cell in a micromachined structure have been designed and fabricated for in situ FT-IR monitoring of electrochemical reactions. The cavity of thin-layer cell has been made using anisotropic etching of silicon by TMAH (tetramethylammonium hydroxide). Thin film gold working electrode mesh, gold counter electrode and silver reference electrode layers were patterned by lift-off method, and the thin film silver/silver chloride reference electrode was formed by surface chemical reaction of thin-film silver in $FeCl_3$ solution. Electrochemical, spectroscopic and spectroelectrochemical characteristics have been tested using the fabricated device and have been compared with those of commercially available $CaF_2$ thin-layer cell. For both cells, the same concentration of chemicals were used; 2mM $K_3Fe(CN)_6$ in aqueous solution and 2mM ferrocene ($C_5H_5-Fe-C_5H_5$) in dichloromethane ($CH_2Cl_2$) solution. Cyclic voltammetry has been used to test electro-chemical characteristics while FT-IR spectrometry has been used to monitor spectroscopic characteristics. The possibility of fabricated thin-layer cell has been tested successfully for both aqueous and nonaqueous solvent system.