Many precious metals have useful qualities in terms of resisting corrosion, conducting heat or electricity, and such. In a lab doing this kind of work, they are

Many precious metals have useful qualities in terms of resisting corrosion, conducting heat or electricity, and such. In a lab doing this kind of work, they are likely to have those materials just lying around. Read it as "we used super-high-end electrode materials because we had them on hand, but the process doesn't actually require them".