A sol includes metal oxide nanoparticles dispersed in an aqueous liquid, and further includes stabilizer ions. The metal oxide particles include one or more metals selected from a first group consisting of cerium, zirconium, iron, manganese and titanium, and one or more metals selected from a second group consisting of platinum, palladium, rhodium, ruthenium, iridium and osmium. The sols can be used to deposit catalytic coatings onto catalyst substrates, including substrates with narrow channels (i.e. channels with a diameter of less than 500 μm).