DC motor spun clockwise then counter clockwise creates AC current?
Well, if you reverse direction you will have an AC voltage at the motor terminals, frequency proportional to the period of reversal, peak amplitude proportional to peak shaft speed. It isn't necessarily sinusoidal unless the shaft speed is sinusoidally driven. This is assuming you are talking about a DC brush motor?  A brushless DC motor will give you an AC voltage at the terminals if you drive it in either direction.  Frequency and amplitude will be proportional to shaft speed.

I don't get the link between capturing as much "current" as possible and converting the output to an AC voltage, maybe you could explain a little more about what you are trying to accomplish?