Three-dimensional nitrogen and sulfur co-doped holey-reduced graphene oxide frameworks anchored with MoO2 nanodots for advanced rechargeable lithium-ion batteries

In this manuscript, we synthesize a porous three-dimensional anode material consisting of molybdenum dioxide nanodots anchored on nitrogen (N)/sulfur (S) co-doped reduced graphene oxide (GO) (3D MoO₂/NP-NSG) through hydrothermal, lyophilization and thermal treatment. First, the NP-NSG is formed via hydrothermal treatment using graphene oxide, hydrogen peroxide (H₂O₂), and thiourea as the co-dopant for N and S, followed by calcination of the N/S co-doped GO in the presence of ammonium molybdate tetrahydrate to obtain the 3D MoO₂/NP-NSG product. This novel material exhibits a series of out-bound electrochemical performances, such as superior conductivity, high specific capacity, and excellent stability. As an anode for lithium-ion batteries (LIBs), the MoO₂/NP-NSG electrode has a high initial specific capacity (1376 mAh g^-1), good cycling performance (1250 mAh g^-1 after 100 cycles at a current density of 0.2 A g^-1), and outstanding Coulombic efficiency (99% after 450 cycles at a current density of 1 A g^-1). Remarkably, the MoO₂/NP-NSG battery exhibits exceedingly good rate capacities of 1021, 965, 891, 760, 649, 500 and 425 mAh g^-1 at different current densities of 200, 500, 1000, 2000, 3000, 4000 and 5000 mA g^-1, respectively. The superb electrochemical performance is owed to the high porosity of the 3D architecture, the synergistic effect contribution from N and S co-doped in the reduced graphene oxide (rGO), and the uniform distribution of MoO₂ nanodots on the rGO surface.