I believe it was post Infinity War, but Peter was still alive. Anyway, the world was having major ecological problems, and Tony was coming up with ways to fix the pollution in the air and oceans using nanites. The air had caught fire near Europe. Also, Tony saved the earth from alien aggressors by using nanites as weapons to destroy their spaceships. Carol or the Guardians told him he'd have to sign a treaty promising not to pass on how to make and use nanites.
Anyone have any idea of the title or author? I think I read it a few months ago
Thanks for your help.