Angew. Chem. Int. Ed. http://doi.org/f23gms (2015)

By encapsulating a liquid droplet in solid particles, miniature reactors can be created that are capable of carrying out a variety of processes, including the synthesis of nanocomposites and photochemical polymerizations. However, the applications of these 'liquid marble' reactors are typically restricted to room-temperature reactions due to the difficulties involved in heating them. Xing Yi Ling and colleagues have now shown that graphene can be used to create heatable liquid marble reactors.

The researchers — who are based at Nanyang Technological University, Fudan University, the Institute of Materials Research and Engineering, Singapore, and the University of Brunei Darussalam — created the graphene liquid marbles by rolling a microlitre droplet of water on a bed of pulverized graphene nanoplatelets. Then, by firing a laser at the marbles, the miniature reactors could be instantly heated thanks to the favourable photothermal properties of graphene; by adjusting the power of the laser, the temperature of the encapsulated water could be varied between 21 °C and 74 °C.

To illustrate the capabilities of the reactors, Ling and colleagues show that the reaction kinetics of the methylene blue degradation reaction can be modulated and, compared with a reaction without photothermal heating, a 12-fold enhancement in reaction rate achieved.