An optimum morphology of platinum nanoparticles with excellent electrocatalytic activity for a highly efficient dye-sensitized solar cell

► An optimum morphology of Pt NPs was obtained through controlling the heating rate. ► The Pt-NPs localized at the grain boundary facilitated electron conductivity. ► The lowest charge transfer resistance was achieved at the heating rate of 1.2 °C min−1. ► The Pt counter electrode prepared at 1.2 °C min−1 exhibited the best performance. ► The highest photo-conversion efficiency was 9.30%.