In this study, we reported the synthesis of the two-dimensional (2D) nanocomposite of molybdenum disulfide and nitrogen-doped graphene oxide (MoS2/nGO) as a platinum-free counter electrode (CE) for dye-sensitized solar cells (DSSCs). X-ray photoelectron spectroscopy (XPS), high-resolution transmission electron microscopy (HRTEM), and Raman spectroscopy were used to examine the characteristics of the 2D nanocomposite of MoS2/nGO. The cyclic voltammetry (CV), electrochemical impedance spectra (EIS), and the Tafel polarization measurements were carried out to examine the electrocatalytic abilities. XPS and Raman results showed the 2D behaviors of the prepared nanomaterials. HRTEM micrographs showed the direct evidence of the 2D nanocomposite of MoS2/nGO. The results of electrocatalytic examinations indicated the MoS2/nGO owning the low charge transfer resistance, high electrocatalytic activity, and fast reaction kinetics for the reduction of triiodide to iodide on the electrolyte–electrode interface. The 2D nanocomposite of MoS2/nGO combined the advantages of the high specific surface of nGO and the plenty edge sites of MoS2 and showed the promoted properties different from those of their individual constituents to create a new outstanding property. The DSSC with MoS2/nGO nanocomposite CE showed a photovoltaic conversion efficiency (PCE) of 5.95 % under an illumination of AM 1.5 (100 mW/cm2), which was up to 92.2 % of the DSSC with the conventional platinum (Pt) CE (PCE = 6.43 %). These results reveal the potential of the MoS2/nGO nanocomposite in the use of low-cost, scalable, and efficient Pt-free CEs for DSSCs.
This paper reports architecturally designed nanocomposites synthesized by hybridizing the two-dimensional (2D) nanostructure of molybdenum disulfide (MoS 2 ) nanosheet (NS)-supported Pt nanoparticles (PtNPs) as counter electrodes (CEs) for dye-sensitized solar cells (DSSCs). MoS 2 NSs were prepared using the hydrothermal method; PtNPs were subsequently reduced on the MoS 2 NSs via the water-ethylene method to form PtNPs/MoS 2 NSs hybrids. The nanostructures and chemical states of the PtNPs/MoS 2 NSs hybrids were characterized by high-resolution transmission electron microscopy and X-ray photoelectron spectroscopy. Detailed electrochemical characterizations by electrochemical impedance spectroscopy, cyclic voltammetry, and Tafel-polarization measurement demonstrated that the PtNPs/MoS 2 NSs exhibited excellent electrocatalytic activities, afforded a higher charge transfer rate, a decreased charge transfer resistance, and an improved exchange current density. The PtNPs/MoS 2 NSs hybrids not only provided the exposed layers of 2D MoS 2 NSs with a great deal of catalytically active sites, but also offered PtNPs anchored on the MoS 2 NSs enhanced I 3 − reduction. Accordingly, the DSSCs that incorporated PtNPs/MoS 2 NSs CE exhibited an outstanding photovoltaic conversion efficiency (PCE) of 7.52%, which was 8.7% higher than that of a device with conventional thermally-deposited platinum CE (PCE = 6.92%).
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