Decon is a brand name for rat and mice bait, not a disinfectant. DE (diatomaceous earth) is a desiccant and a mechanical insecticide that some swear by and some think is not useful. Use codex food grade not pool grade if you want to try it.
I use good old dilute bleach to disinfect the coop after I clean it (use good ventilation and confine the chickens away from the area until it is dry). Also look up Vanodine and Oxine as cleaners.