Synthesis of transition-metal (VIB)-compound catalysts as counter electrodes in dye-sensitized solar cells

Transition-metal (VIB) carbides (TMCs) and oxides (TMOs) were prepared by a simple acetamide–metal route for use as counter electrodes (CEs) in dye-sensitized solar cells (DSSCs). Acetamide served as the source of carbon and oxygen because it is cost-effective and a good chelating agent, as well as it does not pollute the environment. The carbides and oxides thus prepared were characterized by X-ray diffraction, scanning electron microscopy, and nitrogen sorption. These catalysts comprising Cr3C2, Cr2O3, WC, WO2, Mo2C, and MoO2 exhibited satisfactory catalytic activities for the reduction of I3− to I− in DSSCs, as evidenced by the results obtained from cyclic voltammetry, electrochemical impedance spectroscopy, and Tafel polarization measurements. WC exhibited the best catalytic activity with the maximum photoelectric conversion efficiency. A power conversion efficiency (PCE) of up to 4.83% was obtained for the device using WC as the CE, among other materials, while those of 3.24% (Mo2C), 4.44% (Cr3C2), 4.67% (WO2), 2.73% (Cr2O3), and 2.53% (MoO2) were obtained for other DSSCs.