Quantum capacitance induced by electron orbital reconstruction of g-C3N4/Co3O4 heterojunction: Improving electrochemical performance.

Utilizing diverse material combinations in heterogeneous structures has become an effective approach for regulating interface characteristics and electronic structures. The g-C3N4/Co3O4 heterostructures were fabricated by uniformly modifying Co3O4 nanoparticles onto discrete clusters of g-C3N4 nanosheets. Then, they were subsequently employed as positive electrode materials for assembling hybrid supercapacitors. According to the first-principles calculation, Co3O4 and g-C3N4 formed Co-N ionic bonds, establishing interfacial space symmetry-broken heterojunction and direct exchange and superexchange between ions at the interface and sub-interface. This resulted in a high-density spin-orbit hybrid heterogeneous polarization interface, significantly improving the quantum capacitance of heterojunction materials. Experimental results showed that the heterojunction had a specific capacitance of 2662 F g-1 at 1 A g-1. When the power density was 750 W kg-1, the energy density reached 128 Wh kg-1. Even when the power density was 16850 W kg-1, it could show an energy density of 62.5 Wh kg-1. The g-C3N4/Co3O4 heterojunction could realize high energy density charge storage as the cathode material of supercapacitors. The construction of heterogeneous polarization interfaces for high-energy quantum capacitors provides a new and effective method for the energy storage field.