Decoupling thermoelectric parameters induces significantly enhanced thermoelectric properties of oxygen-functionalized graphene nanoribbon

The coupling of thermoelectric parameters greatly limits the improvement of thermoelectric properties, which in turns restricts their applications. In this work, we introduce a strategy for significantly enhancing the thermoelectric performance of oxygen-functionalized graphene nanoribbons (GNRs). In particular, the thermoelectric figure of merit (ZT) can be increased from 0.05 (for GNRs) to 0.16 and 0.11 for epoxide-and hydroxylfunctionalized GNRs (GPO and GPOH), respectively. This is mainly attributed to a significant decrease in thermal conductance and a slight decrease in power factor. Especially, the thermoelectric parameters of etherfunctionalized GNRs (GPOV) are relatively decoupled, and the simultaneous increase in power factor and decrease in thermal conductance lead to a sharp increase in their ZT value. Notably, the room-temperature ZT value of GPOV can be increased to as high as 0.5, which is 10 times greater than that of the pristine GNRs. This work reveals the application potential of oxygen-functionalized GNRs in thermoelectric materials, and demonstrates the broad prospects of the present strategy in the field of thermoelectrics.