Platinum nanoparticles-loaded holey reduced graphene oxide framework as freestanding counter electrodes of dye sensitized solar cells and methanol oxidation catalysts

Platinum nanoparticles (PtNPs)-loaded holey reduced graphene oxide framework (Pt/HGF) has been synthesized as freestanding counter electrodes (CEs) of dye sensitized solar cells (DSSCs) and methanol oxidation catalysts. PtNPs (∼2.5 nm) are uniformly incorporated into holey reduced graphene oxide framework by a solvothermal treatment. Pt/HGF possesses high specific surface area (340.65 m² g⁻¹). Its charge transfer resistance (R_CT) at the I⁻/I₃⁻ electrolyte/CE interface reaches 1.61 Ω cm², lower than that of pure Pt (2.99 Ω cm²) and PtNPs loaded non-hole reduced graphene oxide (Pt/G, 2.37 Ω cm²), and its R_CT at the methanol electrolyte/electrode interface (0.75 Ω cm²) is much lower than that of Pt/G (3.14 Ω cm²), showing good electrocatalytic activity for I⁻/I₃⁻ redox reaction and methanol oxidation reaction (MOR). The assembled Pt/HGF-DSSC achieves a photoelectric conversion efficiency of 5.55% and a short-circuit current density (J_sc) of 12.27 mA cm⁻², better than those of Pt-DSSC (5.19%, 10.50 mA cm⁻²) and Pt/G-DSSC (5.12%, 11.12 mA cm⁻²). In methanol oxidation test, Pt/HGF delivers better electrocatalytic activity and stability than Pt/G. Thus, high electrocatalytic activity and efficient electron/ion transport are achieved by Pt/HGF due to the synergistic effect of well dispersed PtNPs, hierarchical holey structure, and framework, and it may serve as an alternative of pure Pt for DSSC-CEs and MOR catalysts.