What do I need to know for wall-mounted desk
This is perfectly feasible, but you need different brackets. They should extend at least 2/3 of the way to the front edge of your table and be about 2/3 as tall as they are deep, at a minimum. There are a number of similar questions on DIYSE which may give useful details, but the gist of it is to use heavy-duty brackets and robust fasteners. 



I don't know what "black screws" are, but I recommend 8mm (5/16") lag screws in purpose-built anchors, carefully placed in solid portions of your wall and penetrating at least 5cm (2"). For a 2m desk I'd use four or five such brackets, with all provided holes filled with screws. 

You'll  need to fasten the top through the brackets as well, particularly at the rear, to prevent tilt. Use thick screws that penetrate about 3/4 the depth of the top, and pilot appropriately for them. A wrap of tape on your drill bit to indicate depth will prevent catastrophic mistakes.

If either end of the desk contacts a wall, install cleats to carry the load there. They'll add considerable stability to the top. Keep the front ends back a few inches so they don't show, and you can taper the end cut back as well.