Electroless Addition of Catalytic Pd to SnO₂ Nanopowders

A new procedure based on the electroless reduction of PdCl 2 using Sn(II) as reducing agent is reported to efficiently add a controlled amount of Pd to nanoscaled SnO 2 powders. The characterization of these powders using XRD, Raman spectroscopy, XPS, ICP, and TEM is presented and discussed in order to show the feasibility of the proposed catalyst addition mechanism as a useful tool for the improvement of existing catalytic materials for gas sensors. Several palladium salt concentrations and reducing agent ratios and also different annealing temperatures have been used to analyze the influence on the morphology and composition of the samples. Results showed the presence of uniformly distributed metallic Pd clusters on the SnO 2 surface at any annealing temperature and the formation of well-distributed PdO clusters of less than 3 nm after annealing at sufficiently high temperature, with incorporation in this case of palladium into the nanoscaled SnO 2 particles.