Ardunio Curve Tracer Question
Look at the datasheet of the opa2341:


rail-to-rail input and output range
supply 2.5 - 5.5 V


That should would work just fine in my opinion.

If you want to use a 12 V supply, feed it to the power jack on the Arduino board, this will take the 12V to an on-board regulator which will make 5 V from that 12 V.
I would just connect the suppy pins of the opamps to any of teh 5 V VDD pins on the arduino board. The opamp's current consumption will be low enough so that you can "borrow" it from the Arduino's supply.

It is only safe to feed 12 V to the Power jack, the rest of the circuits (Arduino microcontroller + opamps) CANNOT handle 12 V, they will break !
Only the regulator connected to the power jack can handle 12 V.