▎ 摘　　要

Graphene nanosheets (GNs) are prepared from natural graphite by a simple ecofriendly microwave-assisted exfoliation technique. The as prepared GNs are decorated with platinum (Pt) nanoparticles by a simple chemical reduction method and used as a low-cost counter electrode (CE) material for dye-sensitized solar cells (DSSCs). Structure and morphology of the prepared GNs and Pt-decorated GNs (Pt-GNs) are evaluated by X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and selected area electron diffraction (SAED) studies. The electrochemical behavior of GNs and Pt-GNs are compared with std. Pt using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) studies. These studies indicate that the Pt-GNs-based counter electrode offered superior electrocatalytic activity towards the I-/I3(-) redox mediator with enhanced charge transfer rate and exchange current density at the electrode/electrolyte interface over std. Pt and GNs-based counter electrodes. DSSCs are fabricated with std. Pt, GNs and Pt-GNs to determine the photovoltaic performance under 1 Sun illumination (100 mW cm(-2), AM 1.5). It is found that the cell fabricated with 1 wt% Pt-decorated GNs as counter electrode showed an 11% improvement in photovoltaic cell efficiency compared with the cell assembled with std. platinum and other reported graphene-Pt-based composites as counter electrodes.