Which are the materials that absorb heat? and can i somehow convert that absorbed heat into a different form of energy? I am looking into trying to absorb the wasted heat dissipated by laptops,severs ,car engines etc . and trap it somewhere and reuse it to make electricity
You won't be able to use that heat. Unless you get a very precise and well should I say kind of heat trapping material which is impossible thus, you won't be able to save and use that electricity. If it was possible or that easy then the power plants would have been using it for years however it's not so, even though those plants are funded so much!!
All the materials absorb heat.Heat transfer from system to surroundings or from one system to another takes place naturally due to difference in their temperatures.Once they are in equilibrium the heat transfer stops.Heat can be converted into other forms of energy e.g. In Thermal power plants heat by combustion of fossil fuels is used to generate electricity.
Heat dissipated by the electronic devices can also be converted into other forms of energy but we need an efficient system for that.