Platinum nanoparticles deposited on substrates by solventless chemical reduction of a platinum precursor with ethylene glycol vapor and its application as highly effective electrocatalyst in dye-sensitized solar cells

To deposit nanostructured platinum (Pt) on substrates has fundamental and practical significance as Pt is a noble metal and an effective electrocatalyst. In this paper, we report a facile and scalable method to deposit Pt nanoparticles on substrates through the solventless chemical reduction of H2PtCl6 with vapor of ethylene glycol (EG) below 200 degrees C. The Pt nanoparticles have a size below 6 nm, and they homogeneously distribute on the substrates. They have good adhesion to the substrates. They are highly catalytic for the reduction of triiodide that is the chemical reduction at the counter electrode of dye-sensitized solar cells (DSCs). Though DSCs with Pt deposited by the EG vapor reduction and pyrolysis exhibit comparable high photovoltaic efficiency of more than 8% at high Pt loading, the photovoltaic efficiency of DSCs with Pt by the EG vapor reduction is much higher than that by pyrolysis when the Pt loading is quite low. DSCs with a Pt loading of 0.19 mu g cm(-2) deposited by this method can have a power conversion efficiency of 6.61%, which is even higher than that (6.19%) of DSCs with a Pt loading of 0.78 mu g cm(-2) deposited by pyrolysis. Thus, this method can significantly reduce the Pt loading to 1/4 or even lower in comparison with Pt by pyrolysis which has been regarded as the method to deposit Pt with the highest electrocatalytic activity as the counter electrode of DSCs. The excellent electrocatalytic activity of Pt is attributed to the small Pt particle size. (C) 2012 Elsevier Ltd. All rights reserved.