South African with short transit in Beijing flying to Germany, do I need to apply for visa?

I assume that you are flying from some other country to Germany via Beijing. This is always important to mention. Anyway, you should count the hours between your scheduled arrival in China and your scheduled departure from the country. In case that you have less than 24 hours, you are perfectly eligible for 24 hours TWOV.

Ahh yes, I am departing from Taiwan-Beijing-Germany, then on return from Switzerland-Beijing-Taiwan.
Since I have dual nationalities, I am hoping that when I arrive in Beijing I may use my South African passport, would i still need to apply for a visa, since my transit in Beijing would all be less than 24hours.

Do you have a Schengenvisa in your south african passport?
What's your other nationality?

my other nationality is Taiwan, and no I don't have Schengen visa in my South African passport.

So you wanna check-in in Taiwan with your Taiwan passport right?
As you don't need a visa for Germany.
The airline will transmit all passenger details to Beijing immigration and if you show up there with a South Africa passport you may get some trouble especially as there's no visa in this passport.

thank you very much for your help !