Absolutely not. It's unworkable because it puts the onus on - well, who? - to do the policing. That's the main reason ICANN decided not to go ahead with a .xxx top-level domain: it would have put them in the role of content police, which is not within the organisation's remit.
Policing of the content on sites is down to the site's owners; and it's up to parents to keep kids away from inappropriate content.