Tellurium-doped graphene nanoplatelets as outstanding electrocatalysts with an extreme electrochemical stability for cobalt (II)/(III) electrolyte in dye-sensitized solar cells

Abstract

As one feasible alternative to platinum (Pt) catalyst in dye-sensitized solar cells (DSSCs), metalloid tellurium (Te)-doped graphene nanoplatelets (TeGnPs) were synthesized by the simple, efficient and eco-friendly ball-milling of graphite in the presence Te powders. Introduction of Te atoms at the edges of TeGnPs was confirmed with various analytical techniques including time of flight secondary ion mass spectrometry (TOF-SIMS). The TeGnP-CE exhibited significantly improved electrocatalytic activity and electrochemical stability for the Co(bpy)32+/3+ (bpy = 2,2＆prime;-bipyridine) redox couple compared to the Pt-CE. The charge-transfer resistance (Rct) at the CE/electrolyte interface was significantly reduced to 0.15 Ω cm2, which is 10 times lower than that of Pt-CE (1.77 Ω cm2). More importantly, TeGnP-CE displays an extreme electrochemical stability for the Co(bpy)32+/3+ redox couple even after 1,000 potential cycles. The SM315-based DSSC fabricated with TeGnP-CE shows a better power conversion efficiency (PCE = 11.58%) than did Pt (11.03%), suggesting that TeGnP-CE could be one of the best alternatives to Pt-CE in DSSCs.