Nitrogen-Doped Graphene Nanosheets with FeN Core-Shell Nanoparticles as High-Performance Counter Electrode Materials for Dye-Sensitized Solar Cells

A newly designed counter electrode (CE) composed of a hybridized structure of iron nitride (FeN) core-shell nanoparticles grown on nitrogen-doped graphene (NG) is presented for application in dye-sensitized solar cells (DSSCs). The FeN core-shell nanoparticles on NG show an excellent electrocatalytic activity and lower charge-transfer resistance (R-ct) towards the CE (I-/I-3(-)) redox reaction in DSSCs. The hybridized electrode exhibits remarkable cycling stability even after 500 cycles. The energy conversion efficiency of a DSSC cell with core-shell FeN/NG nanohybrids as the CE reaches 10.86%, which is superior to the energy conversion efficiency of 9.93% for a cell with a conventional Pt CE under the same experimental conditions. This work provides a novel approach to fabricate catalytically active electrodes for DSSCs and promotes the development of metal nitride-based electrodes for photovoltaic applications.