Question

Which animals breathe nitrogen?

Answer 1

Our atmosphere is 78% nitrogen, so you breathe it all the time. It serves no purpose to you, however.

So, if you are instead asking if there are creatures that breathe nitrogen to produce energy in a similar way that oxygen does, no. Oxygen is necessary to convert carbohydrates to energy.So the answer is no.

Answer 2

animals use oxygen as a chemical energy source because oxygen gas can react with many other compounds to form oxides, which releases energy and happen spontaneously.

Both carbon and nitrogen can be made to react with oxygen, but otherwise they are pretty inert. So of all the gasses in the air present at over a fraction of a percent, oxygen is the only one we can use for energy.

Hydrogen (and sulfur) are both possible substitutes for oxygen in the role of redox energy source, but are normally pretty small components of our environment. On another planet they might well be the basis of bio-metabolism.

Of course the fact that plants can use carbon dioxide to fix carbon is a different case of biology using a gas out of the air. Its the defining quality of plants!