Electrochemically synthesized nanostructured iron carbide/carbon composite as a low-cost counter electrode for dye-sensitized solar cells

Abstract

Owing to the rapid increase in global energy consumption, which is currently based on fossil fuel combustion, the importance of renewable energy has become increasingly apparent. Solar energy is one of the most promising candidates to replace conventional energy sources, and various types of photovoltaic devices, including dye-sensitized solar cells, are being intensively investigated as a means for the efficient utilization of sunlight. However, the use of Pt in the counter electrodes of dye-sensitized solar cells limits their economic feasibility for practical and industrial applications. In the present study, to develop an active and economical material to replace Pt in dye-sensitized solar cells, we prepare a nanostructured iron carbide/carbon composite by electrochemical anodization of Fe foil followed by heat treatment in carbon-bearing gas atmosphere, which lead to the formation of conformal carbon shell on the surface of crystalline Fe3C. The superior catalytic properties of the iron carbide/carbon composite in the cobalt bipyridine redox electrolyte to those of Pt are confirmed by various electrochemical characterization methods. When used as the counter electrode in a dye-sensitized solar cell, the superior properties of the composite provide an 8.0% increase in power conversion efficiency compared to that achieved with a Pt counter electrode.