Why diode is not demon of Maxwell?

[Stanley514]

Diode should conduct electrons in one direction only.
Why doesn`t it produce power at ambient temperature or any temp.?

 

[DaveC426913]

It merely conducts electrons (that are already present and under and electrical potential); it does not emit them.

 

[granpa]

imagine it were an led
As the electrons and holes recombine at the junction they emit light.
the conduction electrons and holes have to be created somewhere.