NiMoO4/Reduced Graphene Oxide Nanocomposites for Thermoelectric Power Generation

Nickel molybdate (NMO) and its composite with reduced graphene oxide (NMO/rGO) were synthesized using an efficient solvothermal process, yielding NMO nanorods, and they were distributed on rGO sheets. The nanorods were successfully embedded within the rGO matrix. The composition of the elements in the synthesized compounds reveals the formation of NMO and NMO/rGO. NMO shows an n-type semiconducting property, and it shows an increment in electrical conductivity and the Seebeck coefficient between 483 and 573 K. The incorporation of rGO significantly enhanced carrier mobility facilitated by the low-energy barriers between the grains. NMO/rGO shows p-type transport properties, with an increment in the Seebeck coefficient due to the energy filtering effect. The composite exhibited a notable enhancement in the power factor, driven by the increased electrical conductivity and increased Seebeck coefficient due to the synergistic effect. Furthermore, a reduction in thermal conductivity was observed, attributed to phonon scattering centers at the NMO/rGO interface. The thermoelectric figure of merit of the NMO/rGO composite was enhanced by approximately 135 times compared to pristine NMO, demonstrating the potential of rGO to enhance the thermoelectric power generation efficiency.