“Two-dimensional (2D) materials as electrodes” is believed to be the trend for future Li-ion and Na-ion battery technologies. Here, by using first-principles methods, we predict that the recently reported borophene (2D boron sheets) can serve as an ideal electrode material with high electrochemical performance for both Li-ion and Na-ion batteries. The calculations are performed on two experimentally stable borophene structures, namely β₁₂ and χ₃ structures. The optimized Li and Na adsorption sites are identified, and the host materials are found to maintain good electric conductivity before and after adsorption. Besides advantages including small diffusion barriers and low average open-circuit voltages, most remarkably, the storage capacity can be as high as 1984 mA h g⁻¹ in β₁₂ borophene and 1240 mA h g⁻¹ in χ₃ borophene for both Li and Na, which are several times higher than the commercial graphite electrode and are the highest among all the 2D materials discovered to date. Our results highly support that borophenes can be appealing anode materials for both Li-ion and Na-ion batteries with extremely high power density.

We report a controllable wet method for effective decoration of 2-dimensional (2D) molybdenum disulfide (MoS₂) layers with Au nanoparticles (NPs). Au NPs can be selectively formed on the edge sites or defective sites of MoS₂ layers. The Au-MoS₂ nano-composites are formed by non-covalent bond. The size distribution, morphology and density of the metal nanoparticles can be tuned by changing the defect density in MoS₂ layers. Field effect transistors were directly fabricated by placing ion gel gate dielectrics on Au-decorated MoS₂ layers without the need to transfer these MoS₂ layers to SiO₂/Si substrates for bottom gate devices. The ion gel method allows probing the intrinsic electrical properties of the as-grown and Au-decorated MoS₂ layers. This study shows that Au NPs impose remarkable p-doping effects to the MoS₂ transistors without degrading their electrical characteristics.