You have to describe your situation and application in detail. Is it the DC pulse or impulse. Level of the DC? pulse width?
The basics would be to turn on a npn transistor and use this transistor to turn on POWER MOSFETS, if you need more power add multiple mosfetets in parallel.
you can see a simple UPS circuit to see the mosfet configurations.
output power will not exceed the input power.
If you want to get high power at output then the input source should be capable of delivering such high power.
I think a piezoelectric material could not deliver high power and i think it could generate small signals only. And if you are using this signals to charge a battery then it may take years to get the battery charged...