The Wirecutter:

If you’d rather add USB charging ports to your outlets than buy USB power adapters, the best option is the Topgreener TU21548A Smart Dual USB Charger Outlet. It’s one of only two models we found that support 4.8-amp charging across two USB ports, meaning it can charge almost any phone or tablet at full speed, without making you give up plug receptacles. The outlet is simple to install and standards-certified for safety, and it won’t look out of place in any setting.

I’m not a fan of these devices (mostly because I’m an incompetent boob when it comes to tools and installing stuff) but this is important because if you do this wrong or buy an inferior product, you could have serious issues. Wirecutter says there are only two models that meet their standards.