hey i dint know about tulasi emitting more oxygen but ya will be glad to look for some more plants to be kept where we can get plenty of O2.may be other members can throw some light on
fig tree or peepal tree or bhuddha tree as it is called by different names in india is the tree which emits oxygen at the night also as well as in the day.... and the second one is banyan tree which emits large amount of oxygen... these are the 2 trees which i know.
Supposedly spider plants in the home will get rid of certain toxicity like from new carpeting or other chemical fumes.
My favorite plant that I would like to add to the list is Ficus Elastica, commonly known as rubber plants. They are very effective in removing toxins in the air and very easy to grow as well. Here is some more info Rubber Plants (Ficus elastica)
Don't know much about the plants that emit oxygen but I do know that certain plants absorb a lot of toxins and pollutants like formaldehyde, carbon monoxide and trichloroethylene. Here are some of them Philodendrons - heart leaf Money plant (pothos) Certain palms - areca, reed and dwarf date Boston fern Weeping fig Peace lily English ivy I learnt that flowering plants - gerber daisy and chrysanthemum and snake plant (mother-in-law's tongue) are also good toxin removers. Sindhu