Charging a USB device with ac connection
If your adapter outputs 5v DC then yes, but in that case it's a bit more than a physical adapter. Under no circumstances can a USB device be connected to an AC source without first converting the AC source to DC and regulating the voltage to 5v (assuming USB 2.0/3.0 -- USB C and the 3.1/3.2 standards allow for higher voltage if proper components are on both sides. )