Offhand I don't see anything wrong with the physics, although the article you pointed to has mistakes in it. There is no way to generate tritium as a by product of neutron beta decay (or, rather, you would have to start with a core of three neutrons, which isn't exactly something you'd drop by Walmart to pick up). I suspect tritium might actually be the fuel (since it decays through beta decay in to helium-3). If so, creating enough of it would probably be the most expensive aspect. It is patently wrong to say this is not "Nuclear". It's not fission or fusion, but the primary process is a nuclear radioactive decay event.

So, the short version is you have some material that spits out relatively high energy electrons, which they are able to cause to cascade and drive a current. How cheaply this can be done, I would definitely question.

No hoax. The technology is 50 years old. But the article is misleading.

"Although betavoltaic batteries sound Nuclear they’re not, they neither use fission/fusion or chemical processes to produce energy and so (do not produce any radioactive or hazardous waste)."

The process is nuclear, but the process of decay emits beta particles (high speed electrons & positrons), not gamma rays, which we all know causes the public to turn green, musclebound and sociopathic.