Mn3O4 nanocluster-graphene hybrid for energy storage and electrochemical sensing application

In this report, uniformly dispersed tri-manganese tetra-oxide (Mn3O4) nanoclusters on reduced graphene oxide (rGO) were synthesized and used as an electrode material for high-performance supercapacitor application. HRTEM images associated with SAED and EDS confirm the formation of Mn3O4 nanoclusters on rGO while FTIR shows clear evidence of Mn3O4 nanocluster deposition on rGO. The nanohybrid structure is unique showing uniformly distributed Mn3O4 nanoclusters of size from 2 to 20 nm with the majorities of the cluster sizes are in the range of ~ 5-11 nm. The nanoclusters exhibit trapped mesopores of size ~ 2 nm inside of the clusters surrounded with tiny Mn3O4 nanoparticles, which not only improves the surface properties but also enhances the electrochemical activities of rGO. We believe that the low-temperature, hydrothermal processing of KMnO4 solution leads to the development of such nanoclusters formed by limited growth of ultra-nanosized nucleates deposited on rGO surface under optimized time condition. The nanohybrid shows the highest capacitance value of 181 F/g at a current density of 0.3 A/g along with superior cyclic stability (with ~ 95% capacitance retention upon continuous 2000 cycle). The nanohybrid material was further utilized for electrochemical sensing of H2O2 where anodic current proportionally increases as a function of H2O2 concentrations. We believe that the nanohybrid material described here will have potential applications in the area of high-performance supercapacitor, catalysis, batteries, and non-enzymatic sensors.