Efficient hydrothermal-processed platinum nickel bimetallic nano-catalysts for use in dye-sensitized solar cells

Cubic platinum (Pt), nickel (Ni), and PtNi bimetallic nano-crystals with slender tentacles are prepared by a hydrothermal method and used as the counter electrode (CE) materials for dye-sensitized solar cells (DSSCs). The influences of the hydrothermal time on the yield, morphology, electrocatalytic and photovoltaic performances of the PtNi bimetallic nano-crystals are investigated. Cyclic voltammetry and electrochemical impedance spectroscopy measurements indicate that the 2 h hydrothermal-processed PtNi CE has the highest catalytic activity for the reduction of triiodide to iodide and the lowest charge transfer resistance at the electrolyte/electrode interface among PtNi bimetallic CEs. The DSSC based on the 2 h hydrothermal-processed PtNi bimetallic CE achieves a photovoltaic conversion efficiency of 8.95%, which is close to that of the pure Pt CE (9.24%) under full sunlight illumination (100 mW cm(-2), AM1.5 G) due to its three-dimensional electrocatalytic surfaces. (C) 2015 Elsevier B.V. All rights reserved.