Can’t you just break down water, use the hydrogen to power the electric motor, and I don’t think O2 as a byproduct is bad, now this is of course an ideal condition, but why hasn’t this been looked into more?
The reason to use hydrogen fuel cells is that the extra energy needed to generate the hydrogen is still far better than the carbon output and costly materials needed for making and charging a battery.
This is just absolutely a false statement. Hydrogen is a carbon fuel, because all of it for practical purposes comes from natural gas. Although it is possible to get hydrogen through electrical hydrolysis, this simply is not where hydrogen as a fuel source comes from today.
If you see or hear hydrogen being discussed, translate the word hydrogen to mean 'natural gas' or fossil fuels, because that's what you are actually talking about. We do not currently get hydrogen as a fuel by splitting. We currently get hydrogen as a fuel by splitting hydrogen from natural gas. You would likely be better off just driving a gas car than a hydrogen powered if your goal is overall emissions reductions. Batteries represent an actual renewable technology because right now (not hypothetically) we can and do power the electrical networks that charge them with renewables. In as far as renewable hydrogen is concerned, there basically is none, because it costs so much more so to produce in this manner than it does to get hydrogen from fossil fuels.