SnO 2 coated Ni particles prepared by fluidized bed chemical vapor deposition

Abstract

A Fluidized Bed Metal–Organic Chemical Vapor Deposition (FB-MOCVD) process was developed for the growth of tin oxide thin films on large hollow Ni particles. Tetraethyl tin was used as tin source and dry air both as fluidization gas and oxidant reagent. The SnO 2 films were grown in a FBCVD reactor under reduced pressure (13.3 kPa) in the temperature range of 633–663 K. A series of specific experiments was carried out to optimize the design of the reactor and to determine the range of experimental parameters (flow rate, pressure, temperature) leading to good fluidization of the large hollow Ni particles used as base material. The SnO 2 films deposited on particles exhibited a dense nodular surface morphology similar to that previously observed on flat substrates. The relative thickness of the films was determined by EDS analyses and the real values were measured by SEM on cross-sections of particles. The SnO 2 films exhibit satisfactory thickness uniformity from one particle to another in the same batch and from run to run. XRD studies revealed that the films exhibited good crystallinity with the cassiterite structure. Traces of NiO were found at the SnO 2/Ni interface. Finally, the SnO 2 CVD coated-Ni particles were used as anodes in an electrochemical cell. The potential limit of oxygen evolution measured was that of the SnO 2 layer despite the initial porosity of the hollow Ni particles inherent to their preparation. This work is the first step towards the preparation of high specific surface area electrodes.