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TiO2-based nanosheets (TNS) modified with Fe2O3 and Y2O3 particles (Fe2O3/Y2O3@TNS), possessing a laminar structure with large specific surface area of 382 m2 g−1, were synthesized via a one-pot hydrothermal method. The optimized Fe2O3/Y2O3@TNS (Fe/Y/Ti = 0.1 at%: 0.75 at%: 1) exhibited high photocatalytic efficiency due to the synergistic effect, and the photodegradation rate towards RhB and K2Cr2O7 solutions were 5.82-fold and 2.35-fold higher, respectively, as compared to TNS under visible light. Simultaneous photocatalytic degradation in the Cr(VI)–phenol coexisting system revealed that there was synergism between Cr(VI) reduction and phenol degradation for promoting photocatalytic efficiency. Besides, Fe2O3/Y2O3@TNS demonstrated strong adsorption and excellent photocatalytic regeneration performance for high-chroma crystal violet (CV), showing potential application in the removal of organic or inorganic pollutants. Based on photoluminescence (PL) spectra and photocurrent (SPC) methodology, the separation efficiency of photogenerated e−–h+ pairs could be significantly strengthened. A possible mechanism for enhanced photocatalytic efficiency under visible light was proposed.

A piezoelectric catalyst of the MoS2@TNr composite (MoS2 nanosheets composited with TiO2 nanorods) was synthesized by a two-step hydrothermal method, and can be recycled and reused as an advanced anode material for supercapacitors. In the dark, the MoS2@TNr composite exhibited ultra-fast piezoelectric catalytic performance and good cycle stability on dye degradation; within 10 min, nearly all rhodamine B (50 mL, 20 ppm) was removed from the solution with the assistance of magnetic stirring. After the 5 cycle degradation reaction, the catalyst was reclaimed and applied to electrochemical testing, which showed better supercapacitor capacitance properties than the fresh catalyst due to the introduction of oxygen vacancies generated from the piezoelectric degradation process. The reclaimed catalyst demonstrated an excellent specific capacitance of 249 F g−1 at 1 A g−1, and 92% capacitance retention after 10 000 cycles. Furthermore, as the current density increased to 30 A g−1, the capacitance could maintain 58% of the initial value. Thus, it can be concluded that the abandoned catalysts may serve as a potential electrode material for energy storage; simultaneously, the reutilization could eliminate secondary pollution and decrease the energy consumption in efficiency.

Ethyl cellulose can be applied as an erasable barrier coating. The microstructure of this coating is a key factor that influences the anti-corrosion property. To investigate the correlation between the hole structure and the acid treatment time, the microstructure of the ethyl cellulose immersed in acid for different times was evaluated. Scanning electron microscopy (SEM) showed that holes enlarged by around 100 nm in the samples immersed for longer time. Electrochemical impedance spectroscopy (EIS) implied that the film resistance decreased, while the positron annihilation lifetime measurement indicated that the free-volume holes enlarged with the increase in the immersing time. All the results were in agreement with each other. A model has been proposed to explain the film resistance, where the film resistance was inversely proportional to the cross-sectional area of pores for ion permeation. The experimental data confirmed that free-volume holes acted as the tunnels for the ions permeating through the EC film. This could be a potential method to evaluate the tortuosity of holes in membranes by coupling the membrane resistance with free-volume hole size.

2,2,7,7-Tetrakis-(N,N-di-p-methoxyphenylamine)9,9-bifluorene (Spiro-OMeTAD) is a widely employed hole-transporting layer (HTL) in typical n-i-p structure perovskite solar cells (PSCs). And the p-type dopants of bis(trifluoromethane)sulfonimide lithium salt (Li-TFSI) and tert-butylpyridine (tBP) have to be utilized to improve the hole mobility and film conductivity of Spiro-OMeTAD. However, the incorporation of these additives will cause the issue of deliquescence, strongly speeding up the degradation of the Spiro-OMeTAD layer and thus of the perovskite layer. Herein, we developed a modified Spiro-OMeTAD layer using MoS2 with the 2H semiconducting phase and flower-like microstructure. The addition of MoS2 played an important role in improving the hole mobility and enhancing the film stability of Spiro-OMeTAD. The resulting PSCs based on the MoS2-modified Spiro-OMeTAD HTL delivered a champion power conversion efficiency as high as 20.18%. More importantly, the incorporation of MoS2 could suppress the Li+ migration in the HTL owing to the strong adsorption ability and large specific surface area of flower-like MoS2 nanoparticles. As a result, the fabricated PSC without encapsulation exhibited promising stability by retaining almost 85% of the initial PCE even after 300 h exposure to air while the reference device only retained about 30% of its initial PCE.

ZnTi-LDHs with different morphologies were successfully fabricated via a surfactant-assisted hydrothermal method. With the help of surfactants, we focus on exploring the morphology control of ZnTi-LDHs, and the promotion effects on their photocatalytic performances. Experimental results showed that the type of surfactant affected the morphology of ZnTi-LDHs. With the help of an anionic surfactant (sodium dodecyl sulfate), ZnTi-LDHs with flower-like structures were obtained by the self-assembly of sheets. Triblock copolymers (P-123) led to the formation of ZnTi-LDH particles assembled together. Both a cationic surfactant (CTAB) and non-ionic surfactant (PVP) have less guiding effect on the growth of ZnTi-LDHs. The self-assembled ZnTi-LDH particles exhibit excellent photocatalytic performances in methyl orange degradation when P-123 is added into the solution as a surfactant. The formation mechanism of ZnTi-LDHs with different surfactants has been proposed. This study proposes a common mechanism of surfactants in the formation of ZnTi-LDHs, which is instructive for the further design of LDHs with controlled morphology.

As a two-dimensional (2D) material, molybdenum disulfide (MoS2) exhibits unique electronic and optical properties useful for a variety of optoelectronic applications including light harvesting. In this article, we review recent progress in the synthesis, properties and applications of MoS2 and related heterostructures. Heterostructured materials are developed to add more functionality or flexibility compared to single component materials. Our focus is on their novel properties and functionalities as well as emerging applications, especially in the areas of light energy harvesting or conversion. We highlight the correlation between structural properties and other properties including electronic, optical, and dynamic. Whenever appropriate, we also try to provide fundamental insight gained from experimental as well as theoretical studies. Finally, we discuss some current challenges and opportunities in technological applications of MoS2.

Visible-light-sensitive titanate nanosheets (TNSs) were synthesized with Cr2O3 successfully loaded and well dispersed on Cr(III)-TNSs by a one-step hydrothermal method for enhanced photocatalytic activity. As in our previous reports, the as-prepared samples clearly exhibited a porous flake-like structure with a large specific surface area (300–400 m2 g−1). Accompanied with the hydrothermal growth of the TNSs, the loaded Cr2O3 not only influenced the layered structure of the TNSs, but also brought about a remarkable enhancement of the visible-light response and the separation of photogenerated carriers. The XPS fitting results indicated that the Cr ions mainly existed in the trivalent form and caused a change in the binding states towards Ti and O. Based on the evaluation of the photocatalytic activity, it was found that the Cr(III)-TNSs obtained a significant improvement for RhB and K2Cr2O7 (Cr(VI)) degradation under visible-light irradiation, which was attributed to retarding the charge recombination and the effective electron transfer from Cr2O3 to TNSs. The better photocatalytic activity was obtained with an optimal content (0.5 at%) of Cr3+, and the degradation rate (Kapp) was 2.9-fold and 4.1-fold, respectively, as compared to TNSs. The samples were also evaluated in photocatalytic H2 generation with the photodeposition of Pt nanoparticles as cocatalysts. The results showed that the visible-light H2 production rate of Pt0.25/Cr(III)-TNSs (0.25 wt% of Pt) was observably enhanced under the efficient sacrificial agent/water system, giving a relatively high H2 generation rate of 473 μmol h−1 g−1 at 0.5 at% of Cr3+ content. The cyclic tests demonstrated the good stability and recycling performance of the samples. Alternative mechanisms for the visible-light-sensitive photocatalytic activity were also proposed.

Unique mesoporous microcuboid CeO2 crystals were prepared by a facile method, involving the hydrothermal hydrolysis of a Ce(NO3)3 aqueous solution in the presence of urea at 180 °C followed by calcination at 400 °C, and characterized with XRD, SEM, TEM, BET, Raman, XPS, positron annihilation spectroscopy and TPR. It was found for the first time that the presence of densely populated mesopores in the microcuboid CeO2 crystals results in highly reactive surface lattice oxygen due to the exposure of the mesopore wall surface with high interfacial curvature, thus leading to a significant enhancement in catalytic activity as compared to single crystal CeO2 nanocubes without mesopores.

We report a reliable and effective strategy to synthesize magnetically recyclable Bi2WO6 microspheres using Fe3O4 nanoparticles as supports. The as-prepared hierarchical photocatalyst displays excellent photocatalytic activity and reusability under visible light irradiation.

AgI/TiO2 nanocomposite was prepared and characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD) and diffusive reflectance UV-vis (DRUV-vis) absorption spectra at different temperatures. The AgI/TiO2 nanocomposite exhibits thermochromic switching phenomena at the phase β–α transition temperature of AgI with the evolution of its color from light yellow at ambient temperature to dark khaki at 150 °C. It was found for the first time that the formation of the AgI/TiO2 nanocomposite not only results in a considerable reduction of thermochromic transition temperature of AgI as well as excellent thermochromic reversibility, but also leads to excellent photostability under illumination with an indoor fluorescent lamp. Based on the characterization results by photoluminescence, transient photocurrent decay and positron annihilation spectra, it is concluded that large surface defects, such as I− vacancy clusters (e.g.Ag+–I−V–Ag+–I−V–Ag+) on the surface of AgI as deep electron traps, are responsible for the photodecomposition of pure AgI. The excellent photostability of the AgI/TiO2 nanocomposite is due to the following reason: the surface I− vacancy clusters as deep electron traps in pure AgI are replaced by Ag+–O2−–Ti4+ bonds on the interface of AgI/TiO2, thus Agncluster formation through the surface migration of photogenerated Ag atoms is completely inhibited, resulting in the inhibition of photodecomposition of AgI.