Facile Synthesis of High-Crystallinity Graphitic Carbon/Fe₃C Nanocomposites As Counter Electrodes for High-Efficiency Dye-Sensitized Solar Cells

Abstract

Because of the advantages of both rapid electron transport of graphitic carbon and high catalytic performance of Fe3C nanoparticle, highly crystalline graphitic carbon (GC)/Fe3C nanocomposites have been prepared by a facile solid-state pyrolysis approach and used as counter electrode materials for high-efficiency dye-sensitized solar cells (DSSCs). The content of Fe3C in the composites can be modified by different hydrochloric acid treatment time. In comparison with pure highly crystalline GC, the DSSC based on GC/Fe3C nanocomposite with 13.5 wt % Fe3C content shows higher conversion efficiency (6.04%), which indicates a comparable performance to the Pt-based DSSC (6.4%) as well. Moreover, not only does our DSSCs have comparable performance to that of the Pt-based DSSC (6.4%), but also is more cost-effective as well. To evaluate the chemical catalysis and stability of nanocomposite counter electrodes toward I3(-) reduction and the interfacial charge transfer properties, GC/Fe3C nanocomposites have been quantitatively characterized by cyclic voltammetry, electrochemical impedance spectra, and Tafel polarization curve. All the results have revealed that the GC/Fe3C nanocomposite counter electrodes can exhibit high catalytic performance and fast interfacial electron transfer, which can be acted as a very promising and high cost-effective materital for DSSCs.

Review on the recent progress of carbon counter electrodes for dye-sensitized solar cells

“…Other parameters, such as C d and Z w , are related to surface area of the electrode material and diffusion velocity of the redox couple in the electrolyte, respectively. The higher surface area and faster diffusion rate contribute to the larger C d and smaller Z w , respectively, which are also advantageous for the higher catalytic activity of CE [43,55].…”

“…Tafel polarization curve is another powerful tool to investigate the electrocatalytic activity of counter electrode, which could be recorded on the similar devices to the ones used in EIS measurements. Generally, Tafel curve can be divided into three zones [32,55]. The curve at low potential (|U|<120 mV) is the polarization zone, the curve at middle potential (with a sharp slope) is the Tafel zone, and the curve at high potential (horizontal part) is the diffusion zone.…”

“…In the diffusion zone, limiting current density (J lim ) depends on the diffusion coefficient of I ି /I ଷ ି redox couple in the DSSC system according to the eq.2 [55,58],…”

Patterned growth of vertically aligned carbon nanotube arrays using colloidal lithography and plasma enhanced chemical vapor deposition

“…Which mechanism plays a key role need to be further studied. Nevertheless, iron carbides exhibit excellent properties compared with iron or iron oxide nanoparticles [30][31][32] due to carbon atoms occupying the interstices between close-packed iron atoms [33]. Therefore, the proposed synthesis route could facilitate the direct fabrication of CNT/ Fe 3 C nanocomposites for applications in catalysis, electrochemistry and solar cells.…”

A Novel Poly(3,4-ethylenedioxythiophene)-graphene Oxide/Titanium Dioxide Composites Counter Electrode for Dye-Sensitized Solar Cell

“…The limiting diffusion exchange current density ( lim ) can also be analyzed from Tafel plot using [44] …”