Has anyone looked into running the fuel cell in reverse to recharge it? I remember seeing a demo at a fair where it was a sealed fuel cell and it could go from

Has anyone looked into running the fuel cell in reverse to recharge it? I remember seeing a demo at a fair where it was a sealed fuel cell and it could go from h2 02 to water and then run it in reverse to recreate the o2 and h2. If that's feasible it could simply be a new type of battery, no?