What Diodes?

What diodes are used for Voltage Rectifier (so has to withstand high Reverse Voltage and Forward current)?
How are those Diodes Chemically different?

And why there is a limit in output current of AC adapter/Voltage rectified circuits?
(Ex: I Max = 500mA)

1N4000 to 1N4007 are common rectifiers.

The current limit on most wall warts is due to (I^2)*R heating of the transformer.

The current rating is down to the power dissipation which is dependant on the amount of heat the component can get rid of before it gets too hot.

A low current rectifier diode has thick leads which act like a heatsink and dump heat into the board. A larger rectifier diode will require a real heatsink.

A Schottky diode will generally be able to handle more current than a silicon diode in the same package style because it has a lower voltage drop for a given current.