First of all, that circuit won't work, it's an emitter follower. The output voltage will be under 3.3V no matter what's on the collector.
Now, if you don't have a 28V supply, you'll need to generate the voltage somehow. You could use a boost converter, but also, there are plenty of ways of using an inductor or transformer in the buzzer drive circuit to convert just the waveform itself.
But my recommendation would be to use a different buzzer.