Jingkun Wang,Yanqin Miao,Ze Lu,Qi Zhang,Wenhao Guo,Min Zhao,Xinping Zhai,Huayun Du
Stanene nanodots (SnNDs) derived from layered tin have attracted considerable interest due to their conveniently tunable bandgap and topological superconductivity. However, high-yield exfoliation of ultrathin SnNDs is still a challenge due to the short layer spacing and strong binding energy. In this work, atomically thin SnNDs with a uniform size of 2.3 nm are successfully prepared by utilizing imidazolium ionic liquid-assisted exfoliation. The obtained SnNDs possess a wide bandgap of 2.69 eV, along with notable solvent compatibility (well dispersed in both polar and nonpolar solvents) and excellent stability. Furthermore, we construct Ir(ppy)3-based green OLED with hybridizing SnNDs and graphene oxide (GO) as the hole injection layer (HIL). It proves that the application of SnNDs helps to modulate the work function and passivate surface defects of GO, increasing hole mobility and thereby improving the device performance. Compared to the PEDOT:PSS-based control device, the optimized SnNDs-GO-based OLED demonstrates an improvement of 6.56, 41.06, and 8.16% in current efficiency (CE), power efficiency (PE), and external quantum efficiency (EQE), respectively. This work not only introduces a new approach to preparing 2D SnNDs but also creates a novel HIL material for OLED devices.
2D materials are attracting much attention in the field of cathode catalysts for lithium–oxygen batteries (LOBs) due to their layered structure, unique electronic properties, and high stability. However, different stacking layer structures trigger different catalytic capabilities in LOBs. In this work, tin selenide nanosheets with a black phosphorus-like 2D structure are synthesized and used as the cathode catalyst for LOBs. SnSe nanosheets with exposed stack (200) facets and stack edge facets exhibit superior specific capacity over 20 783 mAh g −1 and ultralong cycle stability over 380 cycles at 500 mA g −1 in LOBs. This demonstrates that the growth of discharge products is mainly concentrated on the 2D surface (200) facets, rather than the stack edge facets. Experimental and theoretical studies reveal that the confined adsorption of Li 2 O 2 on the stack edge facets of SnSe, due to the 2D layer structure and the unique electron distribution, restricts the growth of discharge products. The 2D surface facets of SnSe benefit for the formation and stabilization of LiO 2 intermediates, leading to the efficient formation/decomposition of discharge products. The findings provide in-depth insight into the elusive electrocatalytic mechanism for 2D layer-structures materials in LOBs.
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