I am an Irish citizen and travelling to Nigeria through istanbul. can i get the transit visa at the airport since my transit time is about 14 hours?
As stated in Timatic, the database used by airlines:
Visa required, except for holders of normal passports issued to nationals of Ireland (Rep.) can obtain a visa or an e-visa on arrival, for a max. stay of 3 months. The e-visa can also be obtained online prior to departure at www.evisa.gov.tr.
In other words, you can either apply through the website, or through kiosks at Istanbul airport.