MoS₂ is considered as an ideal electrode material in the field of energy storage due to high theoretical specific capacity and unique layered structure. However, limited interlayer distance and poor intrinsic electrical conductivity restrict its potential real-world application. Herein, an alternately intercalated structure of MoS₂ monolayer and N-doped porous carbon (NC) layer is grown on reduced graphene oxide (rGO) via a chemical intercalated strategy. The expanded interlayer distance of MoS₂ (0.96 nm), enlarged by the intercalation of N-doped porous carbon layers, can enhance ion diffusion mobility, provide additional reactive sites for ion storage and maintain the stability of electrode structure. In addition, the hierarchical structures between rGO substrate and intercalated N-doped carbon layers construct a three-dimensional (3D) conductive network, which can significantly improve the electrical conductivity and the structural stability. As a result, the rGO-supported MoS₂/NC electrode exhibits an ultrahigh reversible capacity and remarkable long cycling stability for sodium-ion batteries (SIBs) and potassium-ion (PIBs). Meanwhile, the as-obtained MoS₂/NC@rGO electrode also delivers a superior cycle performance of 250 mAh·g⁻¹ after 160 cycles at 0.5 A·g⁻¹ when employed as an anode for sodium-ion full cells.

VS₂ with natural layered structure and metallic conductivity is a prospective candidate for sodium-ion batteries (SIBs) and potassium-ion batteries (PIBs). However, due to large radius of Na⁺ and K⁺, the limited interlayer spacing (0.57 nm) of VS₂ generally determines high ion diffusion barrier and large volume variation, resulting in unsatisfactory electrochemical performance of SIBs and PIBs. In this work, flower-like VS₂/N-doped carbon (VS₂/N-C) with expanded (001) plane is grown on reduced graphene oxide (rGO) via a solvothermal and subsequently carbonization strategy. In the VS₂/N-C@rGO nanohybrids, the ultrathin VS₂ “ petals” are alternately intercalated by the N-doped porous carbon monolayers to achieve an expanded interlayer spacing (1.02 nm), which can effectively reduce ions diffusion barrier, expose abundant active sites for Na⁺/K⁺ intercalation, and tolerate large volume variation. The N-C and rGO carbonous materials can significantly promote the electrical conductivity and structural stability. Benefited from the synergistic effect, the VS₂/N-C@rGO electrode exhibits large reversible capacity (Na⁺: 407 mAh·g⁻¹ at 1 A·g⁻¹; K⁺: 334 mAh·g⁻¹ at 0.2 A·g⁻¹), high rate capacity (Na⁺: 273 mAh·g⁻¹ at 8 A·g⁻¹; K⁺: 186 mAh·g⁻¹ at 5 A·g⁻¹), and remarkable cycling stability (Na⁺: 316 mAh·g⁻¹ at 2 A·g⁻¹ after 1,400 cycles; K⁺: 216 mAh·g⁻¹ at 1 A·g⁻¹ after 500 cycles).

Developing metal-free and long lifetime room-temperature phosphorescence (RTP) materials has received tremendous interest due to their numerous potential applications, of which stable triplet-excited state is the core challenge. Here, boron carbon oxynitride (BCNO) dots, emitting stable blue fluorescence and green RTP, are reported for the first time. The obtained BCNO dots exhibit an unexpected ultralong RTP lifetime of 1.57 s, lasting over 8 s to naked eyes. The effective doping of carbon and oxygen elements in boron nitride (BN) actually provides a small energy gap between singlet and triplet states, facilitating the intersystem crossing (ISC) and populating of triplet excitons. The formation of compact cores via crystallization and effective inter-/intra-dot hydrogen bonds further stabilizes the excited triplet states and reduces quenching of RTP by oxygen at room temperature. Based on the water-soluble feature of BCNO dots, a novel advanced security ink is developed toward anti-counterfeiting tag and confidential information encryption. This study extends BCNO dots to rarely exploited phosphorescence fields and also provides a facile strategy to prepare ultralong lifetime metal-free RTP materials.

Weak ion diffusion and electron transport due to limited interlayer spacing and poor electrical conductivity have been identified as critical roadbacks for fast and abundant energy storage of both MoS₂-based lithium ion batteries (LIBs) and sodium ion batteries (SIBs). In this work, MoS₂ porous-hollow nanorods (MoS₂/m-C800) have been designed and synthesized via an annealing-followed chemistry-intercalated strategy to solve the two issues. They are uniformly assembled from ultrathin MoS₂ nanosheets, deviated to the rod-axis direction, with expanded interlayer spacing due to alternate intercalation of N-doped carbon monolayers between the adjacent MoS₂ monolayers. Electrochemical studies of the MoS₂/m-C800 sample, as an anode of LIBs, demonstrate that the superstructure can deliver a reversible discharge capacity of 1, 170 mAh·g^-1 after 100 cycles at 0.2 A·g^-1 and maintain a reversible capacity of 951 mAh·g^-1 at 1.25 A·g^-1 after 350 cycles. While for SIBs, the superstructure also delivers a reversible discharge capacity of 350 mAh·g^-1 at 0.5 A·g^-1 after 500 cycles and exhibits superior rate capacity of 238 mAh·g^-1 at 15 A·g^-1.The excellent electrochemical performance is closely related with the hierarchical superstructures, including expanded interlayer spacing, alternate intercalation of carbon monolayers and mesoporous feature, which effectively reduce ion diffusion barrier, shorten ion diffusion paths and improve electrical conductivity.