TWOV for transit with 12 Hour layover

Hello,
I am a U.S. passport holder and my husband is a Korean passport holder. We will arrive in Nanning around 9:00 Thursday evening from Seoul. Our connecting flight doesn't leave until 11:05 am Friday morning. How can I get the 24 hour transit stamp (I don't think a visa is required for my husbands Korean passport)? Do I need to apply before my trip or will they issue everything at the airport?
Thank you!