Synthesis of rGO/NiFe2O4 nanocomposite as an alternative counter electrode material to fabricate Pt-free efficient dye sensitized solar cells

Abstract

Reduced graphene oxide/nickel ferrite (rNiF) nanocomposites via one pot hydrothermal procedure were synthesised. The synthesised rNiF composite was used as a catalytic counter electrode (CE) material for dye-sensitized solar cell (DSSC). HR-TEM results demonstrates that rNiF composites were firmly enfolded on rGO network, allowing easy electron transfer across the CE-electrolyte interface. The XPS survey scan spectrum of samples demonstrates that the presence of Ni, Fe, C and O in the composite structure. The large amount of porosity and specific surface area was achieved 241.71 (m2/g) and 0.521 (cc/g) by rNiF-25 sample. When rNiF-25 nanocomposite was employed as the CE catalyst in iodine electrolytes, the DSSCs achieved a power conversion efficiency (PCE) of η = 8.41 %, corresponding to 98 % of that of Pt CEs under the illumination. Also, the device maintains 88 % efficiency up to 40 days under ambient conditions without encapsulation. The IPCE of DSSCs for the Pt-based and rNiF-25 based CEs achieves maximum absorption of 81 % and 78 % at 520 nm respectively. The high catalytic activities of rNiF-25 nanocomposite are attributed to synergetic effects from the combination of active NiF structure and conductive graphene which provides efficient charge transport. These findings suggest that rNiF-25 CE can be considered as a promising alternative material to replace Pt counter electrode in DSSCs.