"harvesting energy from graphene is controversial because it refutes physicist Richard Feynman’s well-known assertion that the thermal motion of atoms, known as Brownian motion, cannot do work. Thibado’s team found that at room temperature the thermal motion of graphene does in fact induce an alternating current (AC) in a circuit, an achievement thought to be impossible."

So is this effectively a micro cooler? (Extracting thermal energy?) I experimented with TEC Peltier modules/cells for converting solar concentrator heat to electricity, it's not particularly efficient but it works when there is a sufficient temperature differential.

https://en.m.wikipedia.org/?title=Peltier_device&redirect=no