It took me a couple of reads to realise you were asking about the preposition. Yes, "for" works perfectly, as would "to". "Of" changes the sentence completely - it tells us that no-one had thought of reducing pollution before.

Good effort although I would pay attention to the second and third sentence. "I doubt whether we can use it here." or "I doubt we can use her idea here." The last sentence is a bit baffling, not exactly sure what you're trying to say there. Perhaps: "I'm sure we can use her ideas of reducing pollution to reduce pollution here."

The first sentence is correct! The second sentence doesn't make sense, so instead you should say, "I doubt whether or not we can use her idea here." The third one should say, "I am sure we can use her idea of reducing pollen to reduce pollen here." But actually it sounds more natural to say, "I am sure we can use her idea to reduce pollen." :)