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Post cobalt doped NbSSe was synthesized by combining chemical vapor transport and the hydrothermal method, which exhibited excellent HER performance due to the synergistic effect of cobalt doping and S/Se vacancies.

A defect-type AlOx nanointerface containing Al2+ has been constructed on the surface of NaMn0.6Al0.4O2 by surface segregation and reconstruction, which exhibits excellent Na-storage performance as the cathode of SIBs over a wide temperature range.

Surface modification is an effective strategy to promote charge transport and extraction, reduce the carrier recombination probability, and ultimately improve the performance of perovskite solar cells (PSCs). Borophene is the lightest two-dimensional (2D) layered material, with high carrier mobility and high hardness. In this work, a sonication-assisted liquid-phase preparation technique was developed to prepare borophene quantum dots (BQDs) with uniform size, good dispersion, and high stability. The use of BQDs as a surface passivation agent on the TiO2 layer in an inorganic CsPbI2Br solar cell was presented. It is found that the boron atoms undergo strong interactions with TiO2 and the perovskite, reducing interfacial recombination and forming a cascade energy alignment for effective charge transport. A CsPbI2Br solar cell with a thin BQD interlayer shows high efficiency of 15.31%, whereas the efficiency was 14.24% for the device with no BQDs. The enhancement in efficiency is mainly due to carrier recombination suppression and a decrease in the defect density at the TiO2/CsPbI2Br interface after BDQ treatment. This work demonstrates that high-quality BQDs have great potential to be applied in perovskite solar cells and other optoelectronic devices.

The intercalation and delamination processes of Ti3C2Tx are systematically investigated by using alkylammonium hydroxides (TAAOH) with different chain lengths. TAA+ cations have a key function for the intercalation reaction of Ti3C2Tx nanosheets, and the basal spacing and the crystal phase of TAA+-intercalated Ti3C2Tx at different stages are closely related to the size of the intercalated TAA+ ions, and they are hardly changed with the addition of molar equivalents of TAAOH per mole of Ti3C2Tx and the drying conditions. Moreover, the intercalation process is very rapid and it can be carried out by just 4 h treatment. TAA+-intercalated Ti3C2Tx can be delaminated into Ti3C2Tx nanosheets by hand shaking or repeated washing. By introducing a graphene oxide nanosheet suspension into the Ti3C2Tx nanosheet suspension, Ti3C2Tx/RGO fibers are firstly prepared by a wet-spinning method followed by reducing Ti3C2Tx/GO fibers in HI/CH3COOH solution. Then the Ti3C2Tx/RGO fiber is soaked in KMnO4 solution with different concentrations at room temperature, and a MnO2/Ti3C2Tx/RGO ternary hybrid fiber with good flexibility and capacitance is prepared. The MnO2/Ti3C2Tx/RGO ternary hybrid fiber electrode shows the largest volumetric capacitance of 851 F cm−3 in 1 M Na2SO4 electrolyte and good flexibility. By twisting two of these fiber electrodes together, an all-solid-state symmetric MnO2/Ti3C2Tx/RGO//MnO2/Ti3C2Tx/RGO fiber supercapacitor with PVA–LiCl gel electrolyte is assembled. It not only exhibits a volumetric capacitance of 24 F cm−3 and superior cycle stability of 92% after 10 000 cycles, but also shows outstanding flexibility and mechanical properties in which the volumetric capacitance has no obvious change after bending the supercapacitor at 90° 1000 times. Furthermore, the assembled symmetric supercapacitor shows the maximum volumetric energy density of 2.13 mW h cm−3 at a volumetric power density of 8.16 mW cm−3. This work will open a new application field of Ti3C2Tx-based fibers for new wearable energy storage devices with good energy density and flexibility.

Two-dimensional (2D) materials have gained significant attention owing to their unique physical and chemical properties, which arise mainly from their high surface–bulk ratios and topological effects. Since the discovery of graphene in 2004, the family of 2D materials has expanded rapidly. Thus far, several single-element 2D materials (graphene, phosphorene, etc.) have been reported; the majority of them contain two (MoS2, WSe2, etc.) or more elements (Mo2CTx, CrPS4, Bi2Sr2CaCu2Ox, etc.). Of these, three-element 2D materials, also called ternary 2D materials, represent a rather attractive direction of recent years. Typical ternary 2D materials include metal phosphorous trichalcogenides (MPTs), ternary transition metal chalcogenides (TMDs), transition metal carbides and nitrides (MXenes) and 2D ternary oxides. Ternary 2D systems result in multiple degrees of freedom to tailor their physical properties via stoichiometric variation. Moreover, they exhibit some properties not characteristic of binary 2D systems, such as band gap tuning. In this paper, we have reviewed the recent progress in various ternary 2D materials on the basis of their classification (MPTs, ternary 2D MXenes, ternary TMDs, BCN and other ternary 2D materials). The synthesis methods, structures, key properties (such as band gap tuning, phase transition and topological phase), and their applications, are summarized. In addition, the strategies to tackle challenges, as well as the outlooks of this field, are presented. Ministry of Education (MOE) Accepted version