Not much can be done imo.

It appears the wound has already begun to encapsulate itself.

Trees don't really 'heal', per se. they simply cover over the wound with a layer of bark and continue to add a layer each year. A wound could take a couple/three years to completely cover over.

The black color can stem from wetwood or slime flux disease, which is bacterial in nature. This isn't harmful to the tree, just unsightly, but that should also diminish with time.

And please don't smear any 'wound treatment' or paint or anything on the wound. This only causes moisture to hold/stay up against the wound, eventually causing rot to develop.

Just let nature take its course and things will be fine.

eta: you could use a clipper to trim a little of that ragged bark along the top. Just be careful not to cut into living parts of the bark.

Great, thanks for the feedback!