Pt Filling within Mesoporous Silicon by Electrodeposition

Abstract

The filling of platinum within mesoporous silicon prepared in highly doped p-type silicon was investigated. The deposition of platinum within the mesopores was achieved when using a solution with Pt (II), while the pores were kept empty in a solution with Pt (IV). The particles of platinum were obtained by displacement deposition. The particles were distributed uniformly within the mesopores. The electrodeposition under a weak cathodic polarization resulted in the formation of platinum rods due to the continuous filling from the bottom. The displacement deposition was successfully suppressed by modifying the pore wall by an organic group. The amount of platinum deposition obtained under the cathodic polarization was significantly decreased when using the wall-modified mesoporous silicon. These results suggest that the electrodeposition and displacement deposition occur simultaneously within as-prepared mesoporous silicon.

Effect of Displacement Deposition on Platinum Deposition within Nanoporous Silicon

“…When a noble metal, which has comparably positive electrode potential, is electrochemically deposited on silicon, displacement deposition is known to proceed concurrently with the electrodeposition. Lower current density is generally required with decreasing the pore size because their highly complicated porous structure restricts the penetration of reactants into the pores leading to the deposition reaction proceeding preferentially at the pore opening where the supply of reactants from the bulk is favorable (15,16). Especially in the case of nanoporous silicon, however, further nucleation and growth induced by the displacement deposition are likely to cause the plugging of pore opening impeding the continuous deposition within the nanopores.…”