What's interesting is that H2 + N2 -> NH3 reaction is thermodynamically favorable, so in theory with a good enough catalyst it can be driven at mild conditions.

And this has actually been achieved back in early 2000-s! But the catalysts are very finicky and they get poisoned too quickly for industrial use. Additionally, it'd be nice to be able to use water instead of hydrogen directly.

There are some interesting developments in this area, like this one: https://www.nature.com/articles/s41467-022-34984-1 - they synthesized ammonia using visible light as an energy source.