Alternative Formation of Nitronium Ions

Forgive me, my chemistry experience is limited.

When I went to school we used the basic sulfuric acid + nitric acid to form the Nitronium ion. However I've been reading that the sulfuric acid causes impurities in some process so instead process chemist have been using a sulfuric acid free method. To my knowledge this is not a substitution for another acid. I read something suggesting that instead of protonating the nitronium ion, you take away an electron. Thats the extent of what I know, here.

Are any of you aware of a common way to form a nitronium ion the purpose of nitration. Preferably one that works in a slightly basic solution buffered by sodium bicarbonate.

Thanks in advance.