In one embodiment, a protective coating for an electrode of a sensor is described, the protective coating comprising an annealed catalyst, said annealed catalyst comprising at least one metal that has been subjected to thermal energy that is at least equivalent to or greater than that received from calcining the at least one metal for 24 hours at a temperature of 930 degrees C. in air. In another embodiment, the annealed catalyst will comprise at least one metal that has been subjected to thermal energy that is equal to or less than that received from calcining the at least one metal for 24 hours at 1030 degrees C. in air. In one exemplary embodiment, the annealed catalyst will comprise at least one metal that has been subjected to thermal energy that is equal to that received from calcining the at least one metal for 24 hours at 980 degrees C. in air.