The two-dimensional few-layer black phosphorus (BP) has been proposed as a new type of semiconductor for optoelectronic applications. Beyond optoelectronics, the BP nanostructures have recently shown great potential in producing singlet oxygen for photodynamic therapy, but its underlying mechanism remains elusive. Here, we report the observation of efficient triplet formation in BP quantum dots, which might be responsible for the singlet oxygen generation. In addition to the common dynamic behaviors of semiconductors, a long-lived photoinduced bleaching signal with a lifetime of 26 μs has been explicitly identified in BP quantum dots, which can be ascribed to the intersystem crossing from singlet to triplet states as confirmed by oxygen quenching test. The observation of highly efficient intersystem crossing in BPQDs well explains its superior performance in photodynamic therapy and indicates its exotic spintronic and magneto-optical properties.

•We develop in situ synthesis of GeO2/RGO nanocomposites.•The clathrate retains original 2D features of graphene and high-loading GeO2.•The nanocomposites show the high capacity of 1024.4 mA h g−1 at 0.1 A g−1.•They also exhibit good performance 464 mA h g−1 at 1 A g−1 after 100 cycles.Germanium dioxide/reduced graphene oxide (GeO2/RGO) nanocomposites are promising anode materials for applications in lithium ion batteries because they have ultrahigh lithium ion storage capacity and high structural stability. However, the design of GeO2 based anodes with satisfactory cycling ability and high capacity still presents a big challenge because of strict requirements in the need for a special type of solvent, a complicated preparation process, high energy and material costs, and/or difficulty in process upscaling. In the present work, GeO2/RGO nanocomposite is successfully synthesized as an anode material by a simple and green method, which stacked the GeO2 nanoparticles directly on the reduced graphene oxide sheets in an in situ process. The sample exhibits high specific capacity and enhanced rate capacity as an electrode material for lithium ion batteries. GeO2/RGO nanocomposite shows a higher storage capacity of 1020.4 mA h g−1 (theoretical capacity 1125 mA h g−1) after 30 cycles with a current density of 0.1 A g−1, and a long-term cycle capacity of 464 mA h g−1 even after 100 cycles at 1 A g−1. This good electrochemical performance is due to the superior properties of non-aggregated graphene sheets and homogeneously dispersed GeO2 nanoparticles in GeO2/RGO nanocomposite.

•We develop a universal hydrothermal approach to synthesize of SnS nanobelts.•A novel reduction-oxidation formation mechanism of SnS nanobelts is proposed.•SnS nanobelts maintain a discharge capacity of 889.9 mAhg−1 after 50 cycles.•SnS nanobelts exhibit supercapacitive performance better than other SnS materials.Two-dimensional Sn-based metal compounds (e.g. SnS, SnS2 and SnO2) are exceptionally attractive due to their excellent ion intercalation response and are suitable for use in energy storage devices (e.g. lithium-ion batteries and supercapacitors). However, the application of these dichalcogenides in Li-ion batteries is hindered by limitations in large-scale solution synthesis of SnS nanobelts. In this study, we developed a universal hydrothermal approach for the synthesis of SnS nanobelts and proposed an underlying mechanism for the formation reaction. When used as anode materials for lithium-ion batteries, SnS nanobelts maintain a discharge capacity of 889.9 mAhg−1 after 50 cycles at a current density of 0.1 A/g. The nanobelts also exhibit high electrochemical performance, high rate capacity, and high reversible capacity. These results demonstrate that SnS nanobelts are potential anode materials for high-performance energy storage applications.

•We develop a good approach to synthesize of SnS2/RGO nanocomposites.•Small SnS2 nanoparticles are uniformly distributed on the RGO nanosheets surface.•SnS2/RGO shows good reversible capacity, rate performance and cycle stability.Graphene-based nanocomposites have been widely investigated as promising anode materials because of the high specific capacity and good rate capability. However, effective distributing the nanomaterials into graphene conductive network still remains some challenges. In this study, the supercritical carbon dioxide (SC-CO2) route as a good strategy is developed to prepare SnS2/reduced graphene oxide (RGO) nanocomposites, which integrates the complementary effect of ultrasmall SnS2 nanopaticle and RGO nanosheet in the nanocompositions. The SnS2/RGO nanocomposite exhibits high initial discharge capacity of 1466.1 mA h g−1 (100 mA g−1), good capacity retention of about 492 mA h g−1 (100 mA g−1) after 70 cycles and good rate capacity as an anode material for lithium ion batteries. These results demonstrate that supercritical CO2 (SC-CO2) possess significant technological value to enhance the energy storage properties of other two-dimensional (2D) nanocomposites.

•The WS2/rGO composite were synthesized to improve the battery performance.•The WS2/rGO anode shows a capacity of 431.2 mAh/g, much higher than WS2.•The added graphene oxide is reduced to rGO, improving the conductive properties.•The rGO can avoid the restacking, and promote the reduction of WO3.Two-dimensional transition-metal dichalcogenides, such as tungsten disulfide (WS2), have been actively studied as suitable candidates for anode materials used in lithium ion batteries recently, due to their remarkable ion intercalation properties. However, the difficulties in the synthesis of phase-pure WS2, restacking between WS2 nanosheets, low electronic conductivity and brittle nature of WS2 severely limit its Li-ion batteries application. Here, we adopt a one-pot method for synthesizing of WS2/reduced Graphene Oxide (rGO) composite to improve the battery performance dramatically. The WS2/rGO anode shows a stable discharge capacity of 431.2 mAh/g, at a current density of 0.1 A/g after 100 cycles, while the capacity of bare WS2 is only 65.5 mAh/g under the same condition. The added graphene oxide is reduced to rGO in reaction process and constitute stable composite with WS2, not only avoiding the restacking between WS2 nanosheets and improving the conductive properties, but also promoting the reduction of WO3 effectively. Our work may provide a possible route to avoid oxygen impurities in transition metal dichalcogenides.

We report here a simple, effective, and low cost method to synthesize polythiophene/Pd/TiO2 (PTh/Pd/TiO2) ternary composite microspheres and apply such a composite to photoelectrochemical (PEC) sensing. TiO2 spherical aggregates of 200 nm diameter, consisting of nanoscale building blocks of TiO2, have been prepared by hydrolysis of tetrabutyl titanate in a water-in-oil emulsion system (Vwater/Vacetone = 1/100). Pd species and PTh layer were decorated onto TiO2 microspherical substrates by reduction of Pd salts and polymerization of thiophene, respectively. The high surface area, effective charge transfer, and enhanced light absorption of the ternary composite could improve PEC performance under simulated sunlight. The sensitivity, selectivity, and stability of PEC sensor for detecting l-cysteine were much higher than those of the traditional electrochemical sensor. The detection limit of l-cysteine was 9.24 μM in the linear range of 0.31–5.30 mM. Moreover, the results also indicated a good anti-interference and acceptable accuracy in practical application, providing a rapid and sensitive detection method.Keywords: composite; detection limit; microsphere; photoelectrochemistry; sensitivity; sensor

In the present study, we have successfully synthesized the novel heterostructure of NiS nanoparticle (NP)/CdS nanowire (NW) through solution approach. The first step, CdS nanowires were synthesized by a convenient solvothermal route. Then, NiS nanoparticles were grown on the surface of CdS nanowires in a chemical solution of NiCl2·6H2O and anhydrous ethanol at 200 °C. The new catalyst-assisted growth mechanism of the NiS NP/CdS NW heterostructure has been tentatively discussed on the basis of experimental results. A detailed study of the effect of experimental parameters, such as reaction time, reaction temperature, and reaction solvent are also studied. The as-prepared products are characterized by field-emission scan electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS), and their optical properties are measured by Raman spectra and PL spectra. Furthermore, using CdS nanowires and NiS NP/CdS NW heterostructure as examples, our study suggests that this general method can be employed for construction of other semiconductor heterostructures with novel properties.Graphical abstractThe novel heterostructure of NiS nanoparticle (NP)/CdS nanowire (NW) was successfully fabricated by a two-step chemical solution method. The novel catalyst-assisted growth mechanism has been proposed according to the experimental results.Highlights► We do not need the surface pretreatments to introduce groups’ interconnectivity. ► There are cation vacancies on the surface, which allows foreign ones to dissolve. ► A novel catalyst-assisted growth mechanism of the heterostructure has been proposed. ► In addition, no NiS NP/CdS NW heterostructure has been reported until now.