In standard American English, proper nouns are capitalized. Thus, unlike media, I capitalize Black as the name of an ethnic group–like French, Kashmiri, Chinese, or Native American. I don’t use the term African-American since coming out of the Civil Rights & Black power movement most Blacks I know proudly call themselves Black & because I believe it is an attempt to disassociate from ‘Black power’ & ‘Black is beautiful’.
In my lifetime, Blacks have been called Negroes, Blacks, African-Americans & countless hateful terms. Such conflict over what to call someone & the level of abuse proper names are subjected to is only an issue with the oppressed, including ethnicities, oppressed castes, women, LGBTs. A Black coworker of mine once said about being called African-American, ‘They keep changing our names to make us think something has changed about the way they treat us.’
The only time I don’t capitalize black is when it is used as an adjective, like ‘black & brown-skinned’. I never use the terms ‘race’ or ‘racial’ since I believe different human races do not exist. That would be white supremacist junk science. There is only one human race with truly beautiful physical differences.