Maximizing efficiency in synchronous boost converter
You're trying to use an N-channel MOSFET as a high-side switch. That isn't going to work without a special gate driver that includes a boost circuit.

Besides which, you've got it the wrong way around &mdash; think about which way the body diode is pointing!



You should probably be using a P-channel device at M2, but even then, you have to make its gate drive relative to its source, which is the output voltage, not the input voltage.