Anyone here in Shanghai a certified US notary public?

Notary services must be performed at the US Consular Services office on Nanjing Lu. This is the only legally recognized US notary service in Shanghai. It’s really quite painless – go onto the Shanghai US consulate website and book an appointment online. If you need a witness, you can either bring another US citizen with you (they’ll need to bring their passport), but usually you can just ask someone else there waiting to be a witness for you. I forgot the cost, but it will be on the website.

It is true. The US consulate is the only place that can perform notary services for US documents. But as I have learned recently and quite painfully, they absolutely will not notarize diplomas. So you might as well save yourself a trip if you need to have your diploma notarized. You can try to obtain that from the place where you studied instead. And definitely make an appointment beforehand, otherwise the wait will be very long, if they admit you at all. Here is the website.