What are some soluble compounds of gold?

This is the first in a series of chemistry questions. I am doing some amateur chemical engineering. One of the sub-goals is to form a voltaic cell with a gold cathode. I am unable to find any relevant information on the internet.

What are some soluble compounds of gold? I also want some other information, such as safety.

I plan on synthesizing the gold compound with an electrolytic cell. After finding a suitable way to form a voltaic cell with gold, I will run electricity through the cell in reverse to cause the gold go through oxidation.

The problem is that I need to find a suitable ion that will be able to bond with gold and remain soluble.