• Energy Research

Abstract The lamellar transition metal oxides, sulfides and carbides with expanded interlayer spacing have attracted wide attention due to their enlargeable interlayer diffusion channels and larger contact areas. However, the existence of pillars between the interlayer would occupy the inter layer voids, which would hinder the accommodation of more lithium ion, sodium ion and so on. Pillar-free TiO2/Ti3C2 composite with expanded interlayer spacing was prepared by sintering the pre-intercalated pristine Ti3C2 with TMAOH under N2 atmosphere. The obtained TiO2/Ti3C2 composite showed remarkable capacity (237.8 mAh g−1 at 100 mA g−1) and long-term stability (153 mAh g−1after 100 cycles at current density of 600 mA g−1) as anode material for sodium ion batteries. These remarkable electrochemical properties of pillar-free TiO2/Ti3C2 were ascribed to its effective expanded interlayer distance fixed by TiO2 nanoparticles attached on the edge plane of Ti3C2, pseudocapacitance contribution of TiO2 nanoparticles, and the synergistic effect between TiO2 and Ti3C2. This work offered a general strategy for fabricating pillar-free MXene-based composites with enlarged interlayer spacing.

Abstract The lamellar transition metal oxides, sulfides and carbides with expanded interlayer spacing have attracted wide attention due to their enlargeable interlayer diffusion channels and larger contact areas. However, the existence of pillars between the interlayer would occupy the inter layer voids, which would hinder the accommodation of more lithium ion, sodium ion and so on. Pillar-free TiO2/Ti3C2 composite with expanded interlayer spacing was prepared by sintering the pre-intercalated pristine Ti3C2 with TMAOH under N2 atmosphere. The obtained TiO2/Ti3C2 composite showed remarkable capacity (237.8 mAh g−1 at 100 mA g−1) and long-term stability (153 mAh g−1after 100 cycles at current density of 600 mA g−1) as anode material for sodium ion batteries. These remarkable electrochemical properties of pillar-free TiO2/Ti3C2 were ascribed to its effective expanded interlayer distance fixed by TiO2 nanoparticles attached on the edge plane of Ti3C2, pseudocapacitance contribution of TiO2 nanoparticles, and the synergistic effect between TiO2 and Ti3C2. This work offered a general strategy for fabricating pillar-free MXene-based composites with enlarged interlayer spacing.

COF and TiO2 core–shell structured heterojunctions with the spatial location of two semiconductors either in the core or on the shell are precisely designed.

COF and TiO2 core–shell structured heterojunctions with the spatial location of two semiconductors either in the core or on the shell are precisely designed.

AbstractLithium–sulfur batteries (LSBs) are a class of new‐generation rechargeable high‐energy‐density batteries. However, the persisting issue of lithium polysulfides (LiPs) dissolution and the shuttling effect that impedes the efficiency of LSBs are challenging to resolve. Herein a general synthesis of highly dispersed pyrrhotite Fe1−xS nanoparticles embedded in hierarchically porous nitrogen‐doped carbon spheres (Fe1−xS‐NC) is proposed. Fe1−xS‐NC has a high specific surface area (627 m2 g−1), large pore volume (0.41 cm3 g−1), and enhanced adsorption and electrocatalytic transition toward LiPs. Furthermore, in situ generated large mesoporous pores within carbon spheres can accommodate high sulfur loading of up to 75%, and sustain volume variations during charge/discharge cycles as well as improve ionic/mass transfer. The exceptional adsorption properties of Fe1−xS‐NC for LiPs are predicted theoretically and confirmed experimentally. Subsequently, the electrocatalytic activity of Fe1−xS‐NC is thoroughly verified. The results confirm Fe1−xS‐NC is a highly efficient nanoreactor for sulfur loading. Consequently, the Fe1−xS‐NC nanoreactor performs extremely well as a cathodic material for LSBs, exhibiting a high initial capacity of 1070 mAh g−1 with nearly no capacity loss after 200 cycles at 0.5 C. Furthermore, the resulting LSBs display remarkably enhanced rate capability and cyclability even at a high sulfur loading of 8.14 mg cm−2.

AbstractLithium–sulfur batteries (LSBs) are a class of new‐generation rechargeable high‐energy‐density batteries. However, the persisting issue of lithium polysulfides (LiPs) dissolution and the shuttling effect that impedes the efficiency of LSBs are challenging to resolve. Herein a general synthesis of highly dispersed pyrrhotite Fe1−xS nanoparticles embedded in hierarchically porous nitrogen‐doped carbon spheres (Fe1−xS‐NC) is proposed. Fe1−xS‐NC has a high specific surface area (627 m2 g−1), large pore volume (0.41 cm3 g−1), and enhanced adsorption and electrocatalytic transition toward LiPs. Furthermore, in situ generated large mesoporous pores within carbon spheres can accommodate high sulfur loading of up to 75%, and sustain volume variations during charge/discharge cycles as well as improve ionic/mass transfer. The exceptional adsorption properties of Fe1−xS‐NC for LiPs are predicted theoretically and confirmed experimentally. Subsequently, the electrocatalytic activity of Fe1−xS‐NC is thoroughly verified. The results confirm Fe1−xS‐NC is a highly efficient nanoreactor for sulfur loading. Consequently, the Fe1−xS‐NC nanoreactor performs extremely well as a cathodic material for LSBs, exhibiting a high initial capacity of 1070 mAh g−1 with nearly no capacity loss after 200 cycles at 0.5 C. Furthermore, the resulting LSBs display remarkably enhanced rate capability and cyclability even at a high sulfur loading of 8.14 mg cm−2.

N-doped carbon-MoS2 (NC-MoS2) nanocomposites, including dual–shell, yolk–shell, core–shell, hollow and nanorods, were obtained using a sequential cooperative self-assembly approach. The hollow NC-MoS2 nanocomposites showed enhanced Li-ion storage performance compared to the dual–shell and yolk–shell nanostructures.

N-doped carbon-MoS2 (NC-MoS2) nanocomposites, including dual–shell, yolk–shell, core–shell, hollow and nanorods, were obtained using a sequential cooperative self-assembly approach. The hollow NC-MoS2 nanocomposites showed enhanced Li-ion storage performance compared to the dual–shell and yolk–shell nanostructures.

Three-dimensional assembly of carbon nitride tube was obtained from supramolecular precursor. The special morphology and triazole ring group modification endowed materials' enhanced photocatalytic hydrogen evolution property (71 mmol g−1 h−1).