Relevant question: To recharge them, will you have to feed them?
No.
Viruses do not have any sort of metabolism. They drift until they get into an appropriate target cell, at which point they hijack it and make it make more viruses. Therefore they do not need feeding at the best of times.
However in this case the viruses are being used as convenient particles that will stick to the electrode. We do not care about the health and well-being of the viruses at all.
Relevant question: To recharge them, will you have to feed them?