Ruthenium nanofibers as efficient counter electrodes for dye-sensitized solar cells

•Ru nanofibers synthesized as efficient counter electrodes for DSSCs•Ru nanofibers exhibited rough surfaces consisting of nano-sized grains.•Ru nanofibers showed improved electrochemical performance.•Ru nanofibers achieved higher conversion efficiency than Pt.

The counter electrode has a strong influence on the photovoltaic performance of dye-sensitized solar cells (DSSCs). Thus, we introduce a novel approach where Ru nanofibers consisting of nano-sized grains are used instead of the typical Pt counter electrodes for DSSCs. The Ru nanofibers can be successfully prepared via electrospinning followed by post-calcination and hydrogen reduction. This sequential approach provides a novel nanoarchitecture. This architecture consists of nano-sized grains and a unique network structure, which affords high electrical conductivity. The resultant Ru nanofibers exhibit properties of improved photovoltaic performance: (I) lower charge transfer resistance (12.5 Ω cm− 2), (II) higher short-circuit current density (14.77 mA cm− 2), and (III) higher photovoltaic conversion efficiency (6.23%), which is comparable to a commercial Pt counter electrode. The improved photovoltaic performance of the counter electrode in the DSSC is attributed to the combined effects of small grain size which results in a high number of electrochemical sites, high electrical conductivity that leads to improved electrocatalytic activity, and a unique network structure that allows for rapid electron transfer and rapid diffusion of the electrolyte.

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