Plutonium is an unstable, and poisonous element, not appropriate for every cardholder. (Some of us stable and non-toxic people would be offended.)

Some of the more obscure elements would be better candidates to have a credit card named after them. How about:

The Dysprosium Card: for obscure exclusivity.

The Copper Card: for successful plumbers and electricians.

The Iodine Card: Disinfect while you buy!

The Xenon Card: So exclusive that [no stores are allowed to accept it.

The Germanium, Francium, and Americium cards: tied to FFPs from their respective nations.

Others?