Neat! And it's politely CC-licensed[0].

Boranes have long been known as a high-energy aerospace fuel (e.g. [1]). But this isn't about the general category: it's a specific transition metal one, MnB₂, that has almost twice the volumetric energy density of all the other metal diboranes (fig. 5). (I.e., goes towards density impulse—*not* specific impulse). They're proposing it as a solid rocket fuel, where it might (on paper) replace the aluminum that's used today, that's about 20% of SRB fuel mixtures by mass.

[0] https://pubs.acs.org/doi/10.1021/jacs.5c04066

[1] https://en.wikipedia.org/wiki/Zip_fuel