A novel type of hierarchical nanocomposites consisted of MoS2 nanosheet coating on the self-ordered TiO2 nanotube arrays is successfully prepared by a facile combination of anodization and hydrothermal methods. The MoS2 nanosheets are uniformly decorated on the tube top surface and the intertubular voids with film appearance changing from brown to black color. Anatase TiO2 nanotube arrays (NTAs) with clean top surfaces and the appropriate amount of MoS2 precursors are key to the growth of perfect compositing TiO2 @MoS2 hybrids with significantly enhanced photocatalytic activity and photocurrent response. These results reveal that the strategy provides a flexible and straightforward route for design and preparation nanocomposites based on functional semiconducting nanostructures with 1D self-ordered TiO2 NTAs, promising for new opportunities in energy/environment applications, including photocatalysts and other photovoltaic devices.

There has been significant progress in the field of semiconductor photocatalysis, but it is still a challenge to fabricate low‐cost and high‐activity photocatalysts because of safety issues and non‐secondary pollution to the environment. Here, 2D hexagonal nanoplates of α‐Fe2O3/graphene composites with relatively good distribution are synthesized for the first time using a simple, one‐step, template‐free, hydrothermal method that achieves the effective reduction of the graphene oxide (GO) to graphene and intimate and large contact interfaces of the α‐Fe2O3 nanoplates with graphene. The α‐Fe2O3/graphene composites showed significantly enhancement in the photocatalytic activity compared with the pure α‐Fe2O3 nanoplates. At an optimal ratio of 5 wt% graphene, 98% of Rhodamine (RhB) is decomposed with 20 min of irradiation, and the rate constant of the composites is almost four times higher than that of pure α‐Fe2O3 nanoplates. The decisive factors in improving the photocatalytic performance are the intimate and large contact interfaces between 2D hexagonal α‐Fe2O3 nanoplates and graphene, in addition to the high electron withdrawing/storing ability and the highconductivity of reduced graphene oxide (RGO) formed during the hydrothermal reaction. The effective charge transfer from α‐Fe2O3 nanoplates to graphene sheets is demonstrated by the significant weakening of photoluminescence in α‐Fe2O3/graphene composites.

The treatment of environmental pollution has become one of the most critical issues in the world. Despite the progress made in the study of semiconductor photocatalysis, it is still a challenge to obtain photocatalysts with high activity through relatively simple fabrication processes. In this work, monodisperse CdS spherical nanoparticles (SNPs) of various sizes and good crystallinity are obtained by only adjusting the starting ratio of reactants and the reaction temperature, exhibiting high photocatalytic performances. The photocatalytic rate constant of the ≈ 100 nm CdS SNPs, especially, is more than double that of P25. Furthermore, 3-mercaptopropyltrimethoxysilane is used to assist the interaction between ≈ 200 nm CdS SNPs and citrate-stabilized Au nanoparticles (NPs). The signifi cant increase of photocatalytic activity is confi rmed by the degradation of Rodamine B (RhB) under Xe light irradiation. At the optimal Au concentration (0.5 wt%), the prepared nanohybrids show the highest photocatalytic activity, exceeding that of pure CdS two times. The superior photocatalytic performances of the CdS SNPs-Au nanohybrids can be attributed to the intimate interfacial contact between CdS SNPs and Au NPs, which is a contributing factor to the improvement of transfer and the fate of photogenerated charge carriers from CdS SNPs to Au NPs.

Efficient bifunctional oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) catalysts are of great importance for rechargeable metal–air batteries. Herein, FeNx/C catalysts are synthesized by pyrolysis of thiourea and agarose containing α‐Fe2O3 nanoplate as Fe precursor, where α‐Fe2O3 nanoplate can prevent the aggregation of carbon sheets to effectively improve the specific surface area during the carbonization process. The FeNx/C‐700‐20 catalyst displays excellent catalytic performance for both ORR and OER activity in alkaline conditions with more positive onset potential (1.1 V vs the reversible hydrogen electrode) and half‐wave potential, higher stability, and stronger methanol tolerance in alkaline solution, which are all superior to that of the commercial Pt/C catalyst. In this study, the detailed analyses demonstrate that the coexistence of Fe‐based species and high content of Fe‐Nx both play an important role for the catalytic activity. Furthermore, FeNx/C‐700‐20 as cathode catalyst in Zn–air battery possesses higher charge–discharge stability and power density compared with that of commercial Pt/C catalyst, displaying great potential in practical implementation of for the rechargeable energy devices.

Novel composites composed of α‐Fe2O3 tetrakaidecahedrons and graphene oxide have been easily fabricated and demonstrated to be efficient photoelectrodes for photoelectrochemical water splitting reaction with superior photocurrent response. α‐Fe2O3 tetrakaidecahedrons are facilely synthesized in a green manner without any organic additives and then modified with graphene oxide. The morphological and structural properties of α‐Fe2O3/graphene composite are intensively investigated by several means, such as X‐ray diffraction, field‐emission scanning electron microscope, transmission electron microscope, X‐ray photoelectron spectroscopy, Fourier Transform infrared spectroscopy, and Raman spectroscopy. The tetrakaidecahedronal hematite particles have been indicated to be successfully coupled with graphene oxide. Systematical photoelectrochemical and impedance spectroscopy measurements have been carried out to investigate the favorable performance of α‐Fe2O3/graphene composites, which are found to be effective photoanodes with rapid, steady, and reproducible feature. The coupling of graphene with α‐Fe2O3 particles has greatly enhanced the photoelectrochemical performance, resulting in higher photocurrent and lower onset potential than that of pure α‐Fe2O3. This investigation has provided a feasible method to synthesize α‐Fe2O3 tetrakaidecahedron and fabricate an efficient α‐Fe2O3/graphene photoelectrode for photoelectrochemical water oxidation, suggesting a promising route to design noble metal free semiconductor/graphene photocatalysts.

Herein we report superior dye-adsorption performance for flower-like nanostructure composed of two dimensional (2D) MoS2 nanosheets by a facile hydrothermal method, more prominent adsorption of cationic dye compared with anodic dye indicates the dye adsorption performance strongly depends on surface charge of MoS2 nanosheets. The adsorption mechanism of dye is analyzed, the kinetic data of dye adsorption fit well with the pseudo-second-order model, meanwhile adsorption capability at different equilibrium concentrations follows Langmuir model, indicating the favorability and feasibility of dye adsorption. The regenerable property for MoS2 with full adsorption of dye molecules by using alkaline solution were demonstrated, showing the feasibility of reuse for the MoS2, which is promising in its practical water treatment application.

Core-shell CdS/TiO 2 structures are promising for solar-to-fuel conversion applications because their ideal type-II band alignment helps effective charge transfer to form the CdS + /TiO 2  system. A better understanding of the charge carrier dynamics is critical to provide guiding principles for designing photoelectrochemical (PEC) devices. Hence, TiO 2 shell-thickness dependent charge carrier dynamic and competition between electron relaxation in CdS (e.g. recombination and trapping) and electron transfer from CdS to TiO 2 were investigated using ultrafast transient absorption (TA) spectroscopy. The results indicate that the molar ratio of 2:1 CdS/TiO 2 nanocomposite exhibits the highest electron transfer rate constant of = 2.71×10 10 s -1 , along with an electron relaxation rate of / = 3.43 × 10 10 s -1 , resulting in an electron transfer quantum efficiency of Q ET = 79%, which also corresponds to the best PEC hydrogen generation in the CdS/TiO 2 core-shell composites.However, the electron transfer rate decreases with increasing thickness of the TiO 2 shell consisting of aggregated nanoparticles. One possible explanation is that the CdS and TiO 2 form relatively larger, separate particles, or less conforming small particles, with poor interface with increasing TiO 2 , thereby reducing electron transfer from CdS to TiO 2 , which is supported by SEM, TEM data and consistent with PEC results. Lived trap states contribute to the longer overall charge carrier lifetime or slower electron transfer centers. The thickness and morphology dependence of electron transfer and relaxation provides new insight into the charge carrier dynamics in such composite structures, which is important for optimizing the efficiency of PEC for solar fuel generation applications. 13 focused on the comparison of obtained TA data by the lowest pump power (73 nJ/pulse) to avoid the influence of high-order, nonlinear process. The TB feature of bandgap transition is proportional to the population of the hole population. 37 Therefore, the single-wavelength recovery of the TB features can be assigned to the exciton recombination of the CdS and CdS/TiO 2 core-shell composites, and their relation to the shell-thickness of TiO 2. The recoveries of the TB features of pure CdS and CdS/TiO 2 core-shell composites have been shown in Figure 8 (506 nm, 510 nm, 510 nm and 507 nm for pure CdS, 2:1 CdS/TiO 2 ,1:1 CdS/TiO 2 and 1:2 CdS/TiO 2 , respectively), and all the TB recoveries can be fit with a triple-exponential function. The lifetimes from the fitting are given inTable 1. For the pure CdS, the recovery of the fast component of 6±0.4 ps can be attributed to relaxation or cooling of the free electrons and holes due to excess kinetic energy following generation. The medium (34±2 ps) recovery component is attributed to nonradiative recombination through surface trap states. 43,44 The slow (450±22 ps) recovery component can be attributed to recombination of trapped electron-hole pairs. 45,46After TiO 2 shell is coated on CdS, the TB recovery of the 2:1 Cd...

Graphene nanodots (GNDs) are one of the most attractive graphene nanostructures due to their tunable optoelectronic properties. Fabricated by polystyrene‐nanosphere lithography, uniformly sized graphene nanodots array (GNDA) is constructed as an ultraviolet photodetector (PD) with ZnO nanofilm spin coated on it. The size of GNDA can be well controlled from 45 to 20 nm varying the etching time. It is revealed in the study that the photoelectric properties of ZnO/GNDA PD are highly GNDA size‐dependent. The highest responsivity (R) and external quantum efficiency of ZnO/GNDA (20 nm) PD are 22.55 mA W−1 and 9.32%, almost twofold of that of ZnO PD. Both ZnO/GNDA (20 nm) PD and ZnO/GNDA (30 nm) PD exhibit much faster response speed under on/off switching light and have shorter rise/decay time compared with ZnO PD. However, as the size of GNDA increase to 45 nm, the PD appears poor performance. The size‐dependent phenomenon can be explained by the energy band alignments in ZnO/GNDA hybrids. These efforts reveal the enhancement of GNDs on traditional photodetectors with tunable optoelectronic properties and hold great potential to pave a new way to explore the various remarkable photodetection performances by controlling the size of the nanostructures.