Electrodeposition of uniformly distributed Ru and Ru–Pt nanoparticles onto n-type Si electrodes

We have developed and optimized electrochemical procedure for deposition of the stable and uniformly distributed Ru and Ru−Pt nanoparticles onto n-type Si (n-Si) electrodes. Several plating techniques were tested: cyclic voltammetry (CV), bulk electrolysis (BE), and double-potential-step chronoamperometry (CA). Finally the sequence of the chronopotentiometric (CP) and CA techniques was chosen and applied to control reproducible even-particle electrodeposition on a flat silicon surface, particle size distribution, and to avoid oversized metal inclusions with a diameter of more than 100 nm. The mean diameter of particles was 30 nm, and the modal value was ca. 10 nm. The coverage at the level 2 × 1010 particles/cm2 can be fairly controlled when the CP pretreatment is applied.Furthermore, the electrodeposition of Ru on Si (Si + Ru) was compared to the Ru deposition onto the Si surface covered with Pt nanoparticles (Si–Pt + Ru). Some observations on nucleation and growth of Ru nanoparticles and modification reproducibility could be taken from the CP curves and CA current transients recorded for the series of electrodes. These attempts, and progress in modifications, were monitored by scanning electron microscope (SEM) observations. Finally, the Si−Ru−Pt electrode was tested as an anode in the photoelectrochemical (PEC) cell with aqueous, and also in non-aqueous, Br2/2Br− electrolytes. The steps of modifications with Ru−Pt alloy nanoparticles and its progressive degradation were observed by SEM on the same anode.