Fermion tunneling of charged particles from a non-static black hole in de Sitter space

Introducing a new coordinate system and choosing a set of appropriate matrices \gamma^\mu, this paper attempts to investigate the fermion tunneling of charged particles across the event horizon from the Vaidya--Bonner de Sitter black hole. The result shows that the tunneling rate of the non-static black hole is related not only to the change of Bekenstein--Hawking entropy but also to the integral of the changing horizon, which violates unitary theory and is different from the stationary case.