An embodiment provides a method for stirring a sample in a cell, including: providing a cell comprising a sample chamber; placing a boron-doped diamond electrode on an inner surface of the sample chamber, placing a removable stir bar in the sample chamber, the removable stir bar directly contacting and touching the boron-doped diamond electrode; and wherein the stir bar can be operated to rotate within the sample chamber upon the boron-doped diamond electrode. Other aspects are described and claimed.