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Metal–organic frameworks (MOFs)1–3 are known for their specific interactions with gas molecules4,5; this, combined with their rich and ordered porosity, makes them promising candidates for the photocatalytic conversion of gas molecules to useful products6. However, attempts to use MOFs or MOF-based composites for CO2 photoreduction6–13 usually result in far lower CO2 conversion efficiency than that obtained from state-of-the-art solid-state or molecular catalysts14–18, even when facilitated by sacrificial reagents. Here we create ‘molecular compartments’ inside MOF crystals by growing TiO2 inside different pores of a chromium terephthalate-based MOF (MIL-101) and its derivatives. This allows for synergy between the light-absorbing/electron-generating TiO2 units and the catalytic metal clusters in the backbones of MOFs, and therefore facilitates photocatalytic CO2 reduction, concurrent with production of O2. An apparent quantum efficiency for CO2 photoreduction of 11.3 per cent at a wavelength of 350 nanometres is observed in a composite that consists of 42 per cent TiO2 in a MIL-101 derivative, namely, 42%-TiO2-in-MIL-101-Cr-NO2. TiO2 units in one type of compartment in this composite are estimated to be 44 times more active than those in the other type, underlining the role of precise positioning of TiO2 in this system. Investigation of a chromium-based metal–organic framework shows that the location of added TiO2 inside specific mesopores strongly affects the ability of the material to catalyse photoreduction of CO2.

Mechanical vibrations and solar energy are ubiquitous in the environment. Hereon, we report the synergic enhancement of the oxidation by simultaneously harvesting solar and mechanical vibrations through flexible piezo and photocatalytic composite nanofiber mats. Surface enriched titanium dioxide nanoparticles incorporated in polyacrylonitrile (PAN/TiO

Lithium-rich layered oxides (LLOs) have been extensively studied as cathode materials for lithium-ion batteries (LIBs) by researchers all over the world in the past decades due to their high specific capacities and high charge-discharge voltages. However, as cathode materials LLOs have disadvantages of significant voltage and capacity decays during the charge-discharge cycling. It was shown in the past that fine-tuning of structures and compositions was critical to the performances of this kind of materials. In this report, LLOs with target composition of Li1.17Mn0.50Ni0.24Co0.09O2 were prepared by carbonate co-precipitation method with different pH values. X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscope (TEM), and electrochemical impedance spectroscopies (EIS) were used to investigate the structures and morphologies of the materials and to understand the improvements of their electrochemical performances. With the pH values increased from 7.5 to 8.5, the Li/Ni ratios in the compositions decreased from 5.17 to 4.64, and the initial Coulombic efficiency, cycling stability and average discharge voltages were gained impressively. Especially, the material synthesized at pH = 8.5 delivered a reversible discharge capacity of 263 mAhg−1 during the first cycle, with 79.0% initial Coulombic efficiency, at the rate of 0.1 C and a superior capacity retention of 94% after 100 cycles at the rate of 1 C. Furthermore, this material exhibited an initial average discharge voltage of 3.65 V, with a voltage decay of only 0.09 V after 50 charge-discharge cycles. The improved electrochemical performances by varying the pH values in the synthesis process can be explained by the mitigation of layered-to-spinel phase transformation and the reduction of solid-electrolyte interface (SEI) resistance. We hope this work can shed some light on the alleviation of voltage and capacity decay issues of the LLOs cathode materials.

Li2FeSiO4/C is successfully modified by Li3PO4 additive to achieve excellent electrochemical properties. In comparison with bare Li2FeSiO4/C, the samples with Li3PO4 show no changes in the morphology and structure, which are verified by X-ray powder diffraction and scanning electron microscopy results. High resolution transmission electron microscopy image confirms that Li2FeSiO4/C and Li3PO4 exist in the form of nanocomposites. When used as LIB cathodes, the Li2FeSiO4/Li3PO4/C composites show notably improved electrochemical performance with outstanding high rate performance and superior cyclability than those of Li2FeSiO4/C. The sample with 6 mmol% (LFS-6) exhibits a large discharge capacity of 114.1 mAh g−1 with a remarkable capacity retention of 104.2% over 100 cycles at 10 C, which are much better than those of Li2FeSiO4/C (89.0 mAh g−1 and capacity retention of 75.9%). The enhancement in the electrochemical properties of Li2FeSiO4/C may be attributed to the existence of Li3PO4 additive with high ionic conductivity, which can accelerate the lithium ions diffusion capability and facilitate the charge transfer process.

In this study, oxygen vacancies are successfully introduced into Li2MnO3 by low-temperature reduction. Electron paramagnetic resonance is used to detect oxygen vacancy and the results state clearly that oxygen vacancies indeed exist in the reduced samples, and R-LMO-40 shows the highest content. The relationships between oxygen vacancies content and the electrochemical performance of Li2MnO3 as cathodes for lithium ion batteries are also investigated. The oxygen-deficient samples show much better electrochemical performance compared to the pristine Li2MnO3, especially R-LMO-40 with an optimized content of oxygen vacancies. At the rates of 0.5 C, 1 C, 2 C and 5 C, R-LMO-40 delivers discharge capacities of 143.1, 134.0, 126.1 and 90.9 mAh g−1, respectively. After cycling for 50 cycles, there is nearly no capacity decay. These better electrochemical performances are believed to be related to the characteristics of the oxygen vacancies. Electrochemical impedance spectroscopy analysis clearly indicates that oxygen vacancies can suppress the charge transfer resistance and increase lithium ions diffusion capability. These findings reveal that oxygen vacancies can be utilized to enhance the electrochemical performances of Li-rich oxide cathode materials.

Construction of MOF-based photocatalysts is promising work due to their considerable active sites and flexible structures. Herein, we present a facile double solvent and in-situ-growth strategy to integrate CdS NPs with MIL-101(Cr) to engineer CdS/MIL-101(Cr) composite photocatalyst. As-prepared CdS/MIL-101(Cr) samples were characterized by TEM, SEM, BET, EPR, XPS, TPC and ESI. CdS/MIL-101(Cr) exhibited remarkable enhanced activity for conversion CO2 to CO under visible light irradiation, and the 36% CdS/MIL-101(Cr) showed the optimal performance in the all samples. The superior activity was attributed to following factors. The strong interaction between CdS and MIL-101(Cr) promoted the separation and transferring of the photogenerated charge carriers. A higher utilization efficiency of photoelectrons could be achieved with the MIL-101(Cr) possessing multiple absorptions and active sites for the photoreduction of CO2. Also, CdS/MIL-101(Cr) provided a special transferring path for photoelectrons, from CdS to MIL-101(Cr), then to photoreduction of CO2, which could be certified by the calculation of energy-level and the survey of O2– of CdS and MIL-101(Cr).

The construction of Z-scheme photocatalyst materials mimicking the natural photosynthesis system provides many advantages, including increased light harvesting, spatially separated reductive and oxidative active sites and strong redox ability. Here, a novel Bi

MoS2-modified In2S3 (x wt.%MoS2-In2S3) samples (0 ≤ x ≤ 20) were fabricated through a facile one-pot hydrothermal process. All In2S3 samples modified by MoS2 deliver an excellent Cr6+ removal ability under visible-NIR-light-driven, and 5% MoS2-In2S3 can reduce 20 mg/L Cr6+ solution completely within 30 min with a trace photocatalyst concentration (0.27 mg/mL) which is 3.2-hold higher than that of single In2S3. Further investigations demonstrate that the loaded MoS2 can not only enhance the absorption of light scope but also promote the interfacial electron transfer from In2S3 to MoS2 and then to Cr6+, thus greatly improving the Cr6+ removal ability. ESR shows that the modifying of MoS2 can accelerate the transformation of electrons from the In2S3 to MoS2 which results in that the intensity of O2−• significantly increased. PL, photocurrent, and EIS further identified that the modification of MoS2 can greatly improve the charge carrier separation efficiency. The fabricated MoS2-In2S3 samples also exhibit characteristic features such as stable and reducing Cr6+ in the weak alkaline environment for the first time, which could always be a great challenge for wastewater purification in alkaline condition.

A new binary Mo-based cocatalyst consisting of partially reduced α-MoO3 (MoO3-x) nanoparticles and few-layer MoS2 nanosheets is deposited on AgIn5S8 nano-octahedrons (Octa-AIS) with only (111) facets exposed via an in situ growth process, in which the oxygen-deficient MoO3-x nanoparticles enable facile charge transport due to its high conductivity, while the few-layer MoS2 nanosheets provide more active sites and then excellent catalytic property for H2 evolution. The resultant MoS2-MoO3-x hybrid cocatalyst utilizes the best properties of each component while mitigating their deficiencies, and thus realizes an effective enhancement of visible-light-driven H2 evolution activity on Octa-AIS as compared with the single co-catalyst (such as MoS2, MoO3-x, and even Pt nanoparticles). This study not only presents a rare example of binary Mo-based cocatalyst consisting of MoS2 and MoO3-x components, but also paves a new way to develop an inexpensive photocatalytic system for energy conversion to achieve highly efficient H2 evolution without noble metal-loading.

MnOx/MIL-101 was prepared via incorporating MIL-101, a Cr(III) based MOFs, with MnOx by a photo-deposition method. Multiple techniques XRD, SEM, TEM, XPS, ESR, PL DLS were applied to investigate the structure, photocatalytic activity and mechanism of as-prepared sample. The Cr(III)-oxo clusters in MnOx/MIL-101 and MIL-101 are proposed to be responsible for visible light absorption and also act as an electron trap. MnOx/MIL-101 exhibits much higher photocatalytic activity than pure MIL-101 for degradation of RhB and MB dye under visible light irradiation and the best content of MnOx is 0.050 mol%. This is attributed to the close interaction between MIL-101 and MnOx. The holes can be transferred from MIL-101 to MnOx which is a perfect deriving-hole-types co-catalyst. This not only brings an excellent separation efficiency of the photo-generated carriers, but also another active species •OH, resulting in a higher photocatalytic activity.

Among the Li-rich layered oxides Li2MnO3 has significant theoretical capacity as a cathode material for Li-ion batteries. Pristine Li2MnO3 generally has to be electrochemically activated in the first charge–discharge cycle which causes very low Coulombic efficiency and thus deteriorates its electrochemical properties. In this work, we show that low-temperature reduction can produce a large amount of structural defects such as oxygen vacancies, stacking faults, and orthorhombic LiMnO2 in Li2MnO3. The Rietveld refinement analysis shows that, after a reduction reaction with stearic acid at 340 °C for 8 h, pristine Li2MnO3 changes into a Li2MnO3–LiMnO2 (0.71/0.29) composite, and the monoclinic Li2MnO3 changes from Li2.04Mn0.96O3 in the pristine Li2MnO3 (P–Li2MnO3) to Li2.1Mn0.9O2.79 in the reduced Li2MnO3 (R-Li2MnO3), indicating the production of a large amount of oxygen vacancies in the R-Li2MnO3. High-resolution transmission electron microscope images show that a high density of stacking faults is also intr...

A new kind of metallic Cu-loaded brookite TiO2 composite, in which Cu nanoclusters with a small size of 1-3 nm are decorated on brookite TiO2 quasi nanocube (BTN) surfaces (hereafter referred to as Cu-BTN), is synthesized via a one-pot hydrothermal process and then used as photocatalyst for CO2 reduction. It was found that the decoration of Cu nanoclusters on BTN surfaces can improve the activity and selectivity of CO2 photoreduction to CH4 , and 1.5 % Cu-BTN gives a maximum overall photocatalytic activity (150.9 μmol g-1 h-1 ) for CO/CH4 production, which is ≈11.4 and ≈3.3 times higher than those of pristine BTN (13.2 μmol g-1 h-1 ) and Ag-BTN (45.2 μmol g-1 h-1 ). Moreover, the resultant Cu-BTN products can promote the selective generation of CH4 as compared to CO due to the number of surface oxygen vacancies and the CO2 /H2 O adsorption behavior, which differs from that of the pristine BTN. The present results demonstrate that brookite TiO2 would be a potential effective photocatalyst for CO2 photoreduction, and that Cu nanoclusters can act as an inexpensive and efficient co-catalyst alternative to the commonly used noble metals to improve the photoactivity and selectivity for CO2 reduction to CH4 .

A new kind of brookite TiO 2 /g-C 3 N 4 nanocomposite, in which g-C 3 N 4 nanodots (CNDs) with a mean size of ∼2.8 nm are decorated on brookite TiO 2 quasi nanocube (BTN) surfaces (hereafter referred as BTN-CNDs heterojunction), is prepared via a facile calcination process of the mixture of urea and the home-made BTN powders, and then used as visible-light-responsive photocatalyst for CO 2 reduction. Electron microscopy, X-ray powder diffraction (XRD), ultraviolet-visible light (UV-vis) diffuse reflectance absorption spectra (DRS), X-ray photoelectron spectra (XPS) and its valance band (VB) spectra are adopted to investigate the microstructure, composition, energy band structure, and the possible photogenerated electron transfer processes between BTN and CNDs. After optimizing the photocatalytic condition, enhanced visible-light-driven CO 2 -reduction activity and selectivity for CH 4 generation as compared to g-C 3 N 4 and BTN alone are observed, and a photosensitization mechanism is proposed to explain the differences in the photocatalytic performance among g-C 3 N 4 , BTN, and BTN-CNDs. The pronounced CH 4 generation activity and selectivity over BTN-CNDs heterojunction demonstrate a new strategy for improving the interfacial charge transfer and the photocatalytic CO 2 reduction performance though tailoring the microstructures of the semiconductor-based nanocomposites.

The construction of Z-scheme photocatalyst materials mimicking the natural photosynthesis system provides many advantages, including increased light harvesting, spatially separated reductive and oxidative active sites and strong redox ability. Here, a novel Bi2 S3 nanorod@In2 S3 nanoparticle heterojunction photocatalyst synthesized through one-pot hydrothermal method for Cr6+ reduction is reported. A systematic investigation of the microstructural and compositional characteristics of the heterojunction catalyst confirms an intimate facet coupling between (440) crystal facet of In2 S3 and (060) crystal facet of Bi2 S3 , which provides a robust heterojunction interface for charge transfer. When tested under visible-light irradiation, the Bi2 S3 -In2 S3 heterojunction photocatalyst with 15% Bi2 S3 loading content achieves the highest Cr6+ photoreduction efficiency of nearly 100% with excellent stability, which is among the best-reported performances for Cr6+ removal. Further examination using optical, photoelectrochemical, impedance spectroscopy, and electron spin resonance spectroscopy characterizations reveal greatly improved photogenerated charge separation and transfer efficiency, and confirm Z-scheme electronic structure of the photocatalyst. The Z-scheme Bi2 S3 -In2 S3 photocatalyst demonstrated here presents promise for the removal of highly toxic Cr6+ , and could also be of interest in photocatalytic energy conversion.

Herein, anatase TiO2 with different percentages of exposed {001} and {101} facets was prepared, and subsequently, Ag and MnOx were co-loaded on these TiO2 facets through a classical photodeposition method; the loaded TiO2 samples were labeled as Ag–TiO2–MnOx (N%), where N% denotes the percentage of the exposed {001} facets. The as-prepared samples were analyzed via scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and UV-vis diffuse reflectance spectroscopy (DRS), and the photocatalytic reduction of CO2 was carried out. The results showed that Ag–TiO2–MnOx (40%) exhibited the highest photocatalytic activity among the other dual-loaded samples and pure TiO2. The XPS spectra demonstrated that Ti–O–Mn and Ti–O–H bonds were formed at the interfaces of the cocatalyst-TiO2. The PL and VB spectra revealed that the chemical bond (Ti–O–Mn) at the Ag–TiO2–MnOx (40%) interface greatly increased the hole mobility rate and the photoinduced carrier separation efficiency that resulted in higher catalytic activity for the photoreduction of CO2.

Spinel phase LiMn2O4 was successfully embedded into monoclinic phase layeredstructured Li2MnO3 nanorods, and these spinel-layered integrate structured nanorods showed both high capacities and superior high-rate capabilities as cathode material for lithium-ion batteries (LIBs). Pristine Li2MnO3 nanorods were synthesized by a simple rheological phase method using α-MnO2 nanowires as precursors. The spinel-layered integrate structured nanorods were fabricated by a facile partial reduction reaction using stearic acid as the reductant. Both structural characterizations and electrochemical properties of the integrate structured nanorods verified that LiMn2O4 nanodomains were embedded inside the pristine Li2MnO3 nanorods. When used as cathode materials for LIBs, the spinel-layered integrate structured Li2MnO3 nanorods (SL-Li2MnO3) showed much better performances than the pristine layered-structured Li2MnO3 nanorods (L-Li2MnO3). When charge–discharged at 20 mA·g−1 in a voltage window of 2.0–4.8 V, the SL-Li2MnO3 showed discharge capacities of 272.3 and 228.4 mAh·g−1 in the first and the 60th cycles, respectively, with capacity retention of 83.8%. The SL-Li2MnO3 also showed superior high-rate performances. When cycled at rates of 1 C, 2 C, 5 C, and 10 C (1 C = 200 mA·g−1) for hundreds of cycles, the discharge capacities of the SL-Li2MnO3 reached 218.9, 200.5, 147.1, and 123.9 mAh·g−1, respectively. The superior performances of the SL-Li2MnO3 are ascribed to the spinel-layered integrated structures. With large capacities and superior high-rate performances, these spinel-layered integrate structured materials are good candidates for cathodes of next-generation high-power LIBs.

Brookite TiO2 quasi nanocubes (BTN) decorated with various Cu nanoclusters (Cu NCs) contents (hereafter referred to as Cu/BTN composite) were synthesized via a facile chemical reduction process by NaBH4. The obtained products and its Cu's existential state were characterized by X-ray diffraction, UV–Vis diffuse reflectance absorption spectroscopy, electron microscopy, X-ray photoelectron spectroscopy and X-ray fluorescence spectroscopy. It was found that the introduction of Cu NCs with small size of ∼1–2 nm on BTN surfaces can improve the photocatalytic H2 production activity, and the maximum photoactivity (225 μmol h−1) for H2 production over 1.0 mol% Cu/BTN composite is similar to that (220 μmol h−1) of the benchmark photocatalyst (P25) under the optimum photoreaction conditions, which is 5.2 times higher than that (42.5 μmol h−1) of the BTN alone. This significant enhancement in the photoactivity of BTN is deemed to result from the metallic Cu NCs with high surface area and dispersion, which favour the co-catalyst functions to cause an effective photogenerated carrier separation in space and an improvement in the photocatalytic activity and stability for H2 production. The present results not only demonstrate the brookite TiO2 would be a potential effective photocatalyst for H2 production, but also provide an inexpensive, efficient and stable means of enhancing light-to-hydrogen energy conversion by using metallic Cu nanoclusters alternative to the commonly used noble metal co-catalyst.

Lithium-rich layered oxide Li[Li0.2Mn0.54Ni0.13Co0.13]O2 coated with V2O5 layers (labeled as LMNCO@V2O5) has been synthesized and its electrochemical properties as cathode material for lithium ion batteries have been measured and compared with pristine Li[Li0.2Mn0.54Ni0.13Co0.13]O2 (labeled as LMNCO) and LMNCO–V2O5 composite. As a lithium ions insertion host material, both the V2O5 in the LMNCO@V2O5 and the LMNCO–V2O5 can reduce the irreversible capacity losses and improve the Coulombic efficiencies of the cathode in the first charge-discharge cycle. However, for improving the cycling stabilities and the high-rate capabilities of the LMNCO, the effects of the V2O5 coating layers in the LMNCO@V2O5 are far beyond the effects of the V2O5 nanoparticles in the LMNCO–V2O5. When charge-discharged galvanostatically at 25 mA g−1 between 2.0 and 4.8 V (vs. Li+/Li), the LMNCO@V2O5 with 3 wt.% V2O5 exhibits a discharge capacity of 279.5 mAh g−1 in the first cycle and maintains a discharge capacity of 269.1 mAh g−1 after 50 cycles, with capacity retention of 96.3%. In contrast, the discharge capacity of the pristine LMNCO changes from 251.2 mAh g−1 in the initial cycle to 202.2 mAh g−1 in the 50th cycle, with capacity retention of 80.2%; and the LMNCO–V2O5 shows the same capacity fading trend as the pristine LMNCO, with no obvious improvement in the capacity retention. At high rate of 1250 mA g−1, the discharge capacity of the LMNCO@V2O5 can reach 113.6 mAh g−1, which is much higher than the capacities that the pristine LMNCO and the LMNCO–V2O5 can reach. Different effects of V2O5 are due to their different roles in the cathode materials. While the V2O5 coating layer in the LMNCO@V2O5 can reduce the charge transfer resistance at the electrode-electrolyte interfaces and improve the transportation of lithium ions among the LMNCO particles, the V2O5 nanoparticles in the LMNCO–V2O5 can only work as a Li+ ions insertion host material.

Industrial wastewater containing heavy metal ions can cover the full pH range according to the manufacturing process. Alkaline wastewater treatment is still a great challenge because Cr6+ therein has a more negative reduction potential (Cr2O72− + 14H+ + 6e− = 2Cr3+ + 7H2O (ECr6+(Cr2O72−/Cr3+) = E θ − RT nF ln [ OH ] − ) than in acid solution, in which it can be easily reduced by numerous reagents. In this study, weakly alkaline Cr6+ solution has been used to simulate weakly alkaline industrial wastewater, and a reagent capable of excellent reduction efficiency therein has been developed. A series of band-gap-energy-adjustable NiS-ZnxCd1-xS composites has been synthesized by a one-pot hydrothermal method. A more negative conduction band position for ZnxCd1-xS has been achieved by doping and changing the amount of Zn2+ ions to ensure a superior photoreduction ability. All modified samples show excellent photocatalytic efficiency. For example, the reduction efficiency of 10%NiS–Zn0.25Cd0.75S sample is threefold higher than that of Zn0.25Cd0.75S and sixfold higher than that of CdS when deployed at a catalytic level for 30 min. Multiple characterization methods have been applied, and the results show that the improved efficiency can be ascribed to intimate contact between Zn0.25Cd0.75S and NiS. Photoluminescence (PL) and photocurrent measurements and electrochemical impedance spectroscopy (EIS) further elucidate the catalytic mechanism and imply an enhanced charge-carrier separation efficiency between Zn0.25Cd0.75S and NiS.

We present one-pot hydrothemal syntheis of SnS2-In2S3 p-n heterostructures for photocatalytic reduction of Cr6+ to Cr3+. The conduction bands of In2S3 and SnS2 serve as the photogenerated electron donors and acceptors, respectively, forming a p-n junction band alignment improving the photogenerated charge separation efficiency. Through a detailed investigation of photocurrent spectra, photoluminescence spectra and electrochemical impedance, the heterojunction formation is shown to enhance the photogenerated charge separation and transport properties. In addition, the analysis of 5,5-Dimethyl-1-pyrroline N-oxide (DMPO) spin trapping electron spin resonance (ESR) spectra and band structure further testify the p-n junction of the composite catalyst that could accelerate the electron transport and change the pathway of photocatalytic process toward Cr6+ reduction. Furthermore, SnS2-In2S3 heterojunction photocatalyst achieved 3 times and 67 times higher efficiency than pure In2S3 and SnS2 photocatalysts under visible light toward Cr6+ reduction. Moreover, the SnS2-In2S3 p-n heterojunction photocatalyst demonstrates Cr6+ removal in a weak alkaline solution, breaking through the challenge of Cr6+ reduction in an alkaline environment.

To enhance the photocatalytic activity, co-catalysts are often utilized to accelerate rate-limited surface reactions. Herein, various amounts of bismuth oxyselenide (Bi2O2Se) (i.e., 5 to 25 wt%) as a novel co-catalyst were deposited on TiO2 nanoparticles for photocatalytic hydrogen evolution reaction. The 15% Bi2O2Se/TiO2 showed the best enhanced hydrogen production rate of 1240.7 μmol h−1g−1, which was about 50 times greater than that of pure TiO2. The SEM, EDX-Mapping and TEM revealed the mechanism of in-growth of Bi2O2Se on the TiO2. Trapping experiment of superoxide free radical (O2−) and transient photocurrent decay measurement also revealed that the recombination of the photogenerated electron–hole was remarkably suppressed in Bi2O2Se/TiO2 compared to pure TiO2. Detailed analysis of XPS, transient photocurrent responses, electrochemical impedance spectroscopy (EIS) and DFT calculations indicated that there is a strong interaction between Bi2O2Se and TiO2, and the electrons of TiO2 can be injected into Bi2O2Se. These findings show the potential of Bi2O2Se as co-catalytic materials and open a new avenue for solar water splitting.

Compositing nanoparticles photo-catalyst with enormous surface areas metal–organic framework (MOF) will greatly improve photocatalytic performances. Herein, WO3 nanoparticles are partly embedded into pores of MIL-101 or only supported on the outside of representative MIL-101, which were defined as embedded structure WO3@MIL-101@WO3 and coating structure WO3&MIL-101 respectively. Different pH, concentration and loading percentage were researched. XRD, TEM and BET were carried to analyze the composites. Compared with the pristine WO3, all WO3 loaded MOF nanocomposites exhibited remarkable enhancing for the efficiency of photocatalytic degradation methylene blue under visible light. Their activity of the same loading percentage WO3 in embedded structure and coating structure have increased for 9 and 3 times respectively compared with pure WO3. The WO3@MIL-101@WO3 has 3 times higher efficiency than WO3&MIL-101, because the shorter electron-transport distance can make a contribution to electron–hole separation. The further mechanism involved has been investigated by radical quantify experiment, XPS and photoluminescence spectroscopy.

Compositing nanoparticles photo-catalyst with enormous surface areas metal–organic framework (MOF) will greatly improve photocatalytic performances. Herein, WO3 nanoparticles are partly embedded into pores of MIL-101 or only supported on the outside of representative MIL-101, which were defined as embedded structure WO3@MIL-101@WO3 and coating structure WO3&MIL-101 respectively. Different pH, concentration and loading percentage were researched. XRD, TEM and BET were carried to analyze the composites. Compared with the pristine WO3, all WO3 loaded MOF nanocomposites exhibited remarkable enhancing for the efficiency of photocatalytic degradation methylene blue under visible light. Their activity of the same loading percentage WO3 in embedded structure and coating structure have increased for 9 and 3 times respectively compared with pure WO3. The WO3@MIL-101@WO3 has 3 times higher efficiency than WO3&MIL-101, because the shorter electron-transport distance can make a contribution to electron–hole separation. The further mechanism involved has been investigated by radical quantify experiment, XPS and photoluminescence spectroscopy.

Metal-organic frameworks (MOFs)

In this paper, a Li2MnSiO4/carbon/graphene (LMS/C/G) composite is synthesized by a facile one-step synthesis method and shows superior high-rate performances as the cathode materials for lithium ion batteries (LIBs). In the LMS/C/G composite, carbon coated Li2MnSiO4 particles, with sizes of 20–30 nm, are uniformly anchored on graphene nanosheets. When assembled as the cathodes of LIBs and charge–discharged at the high rates of 1 C, 2 C, 5 C and 10 C (1 C = 166 mA g−1), the specific discharge capacities of the LMS/C/G composite can reach 210, 181, 143, and 109 mAh g−1, respectively. These electrochemical performances are much better than the performances of the Li2MnSiO4 composites that simply coated with carbon (LMS/C) or merely wrapped by graphene sheets (LMS/G). Electrochemical impedance spectroscopy (EIS) analysis shows that, compared with composites LMS/G and LMS/C, composite LMS/C/G has smaller charge-transfer resistance through the solid-electrolyte interfaces and faster lithium ions diffusion coefficient in the cathode materials. These much improved electronic and ionic conductivities should account for the superior high-rate performances of the LMS/C/G composite.

The effects of vanadium pentoxide on the electrochemical properties of Li2MnSiO4 as a cathode material for lithium-ion batteries were tested by synthesizing a V2O5 nanowire-modified in situ carbon coated Li2MnSiO4 composite (LMS/C/V2O5) and comparing its performances with that of a Li2MnSiO4 composite without V2O5. In LMS/C/V2O5, the V2O5 nanowires, with diameters of around 10–20 nm and lengths up to tens of micrometers, entangled together and formed a 3D conductive network; the Li2MnSiO4 nanoparticles, with sizes around 30 nm, distributed uniformly in the network frame and tended to adhere to the V2O5 nanowires. In this structure, the LMS/C/V2O5 composite showed a superior performance as a cathode of lithium-ion batteries even with very low carbon content (3.4 wt%). Ex situ X-ray diffraction patterns, electrochemical impedance spectroscopies of the electrodes and the concentration of Mn ions in the electrolyte during the charge–discharge processes explained the effects of the V2O5 nanowires as an additive in the Li2MnSiO4 cathode material. The benefits of the nanowires include maintaining the crystal structure of Li2MnSiO4 during the charge–discharge cyclings, reducing the charge-transfer resistances at the solid–electrolyte interfaces, increasing the lithium ions diffusion coefficient in the cathode and alleviating the dissolution of manganese into the electrolyte of the batteries.

Among the Li-rich layered oxides Li

A new kind of metallic Cu-loaded brookite TiO

Lithium-rich layered oxides are promising cathode materials for next-generation lithium-ion batteries (LIBs) used in electric vehicles, due to their high specific capacity over 250 mAh g−1 and high energy density of ∼900 Wh Kg−1. However, the poor rate performance and inferior cycling stability of current lithium-rich layered oxides have greatly hindered their practical applications in vehicular LIBs, mostly due to the ineffectiveness of conventional synthesis methods in controlling the materials size and morphology. Herein, one-dimensional (1D) hierarchical lithium-rich layered oxide (Li1.15Mn0.54Co0.08Ni0.23O2) nanowires were successfully synthesized by a template-assisted molten-salt method that used α-MnO2 nanotubes as both the manganese source and template. The prepared lithium-rich layer oxide nanowires were ∼60–80 nm in diameter and ∼0.5–1 μm in length, and each nanowire was composed of homogeneous and interconnected primary nanoparticles (5–20 nm). Electrochemical characterization showed that the 1D lithium-rich layered oxide nanowires exhibited impressively high-rate performance, long cycle life, and excellent capacity retention as cathode materials for LIBs. For example, the cathode delivered a high initial discharge capacity of 304.5 mAh g−1 with a Columbic efficiency of 81.2%, and maintained a discharge capacity of 253.3 mAh g−1, 241 mAh g−1, 222 mAh g−1, and 203 mAh g−1 after 100 cycles, at 0.5C, 1C, 2C and 5C, respectively. Moreover, at an even high rate of 10C, 20C and 30C, the lithium-rich layered oxide nanowires could still deliver a discharge capacity of 149 mAh g−1, 121 mAh g−1, and 65 mAh g−1 respectively for 1000 cycles, without any capacity decay. Post-cycling structural analysis showed that the 1D nanowire morphology of lithium-rich layered oxide was well preserved after prolonged charge/discharge cycling at 10C for 1000 cycles. The excellent electrochemical performance can be ascribed to the good structural stability of 1D nanowires, primary nanosized particles, high crystallinity of the 1D Li1.15Mn0.54Co0.08Ni0.23O2 nanowires. This work developed a new strategy to synthesize manganese-based cathodes with controlled morphology and high crystallinity by the combination of suitable manganese source and molten salt.

Three-dimensional macroporous graphene-based Li2FeSiO4 composites (3D-G/Li2FeSiO4/C) were synthesized and tested as the cathode materials for lithium-ion batteries. To demonstrate the superiority of this structure, the composite’s performances were compared with the performances of two-dimensional graphene nanosheets-based Li2FeSiO4 composites (2D-G/Li2FeSiO4/C) and Li2FeSiO4 composites without graphene (Li2FeSiO4/C). Due to the existence of electronic conductive graphene, both 3D-G/Li2FeSiO4/C and 2D-G/Li2FeSiO4/C showed much improved electrochemical performances than the Li2FeSiO4/C composite. When compared with the 2D-G/Li2FeSiO4/C composite, 3D-G/Li2FeSiO4/C exhibited even better performances, with the discharge capacities reaching 313, 255, 215, 180, 150, and 108 mAh g–1 at the charge–discharge rates of 0.1 C, 1 C, 2 C, 5 C, 10 C and 20 C (1 C = 166 mA g–1), respectively. The 3D-G/Li2FeSiO4/C composite also showed excellent cyclability, with capacity retention exceeding 90% after cycling for 100 time...

It is well known that different crystal facets of TiO2 have different surface electronic and atomic structures, which can influence the photocatalytic performance, and appropriate noble metal-loading usually improves the photocatalytic activity. Herein we demonstrate that Pt-loading can reverse the photocatalytic activity order of anatase TiO2 {0 0 1} facets (TiO2-0 0 1) and {0 1 0} facets (TiO2-0 1 0) for the photoreduction of CO2 to CH4. This new phenomenon was discussed on the bases of the experimental data including attenuated total reflectance Fourier transform infrared (ATR-IR) spectra, CO2 temperature programmed desorption (CO2-TPD) curves, transmission electron microscopy (TEM) images and time-resolved photoluminescence (PL) spectra. It is found that the higher photocatalytic CO2 reduction activity of TiO2-0 1 0 without Pt-loading can be attributed to its larger CO2 adsorbed amount and longer charge lifetime as compared with TiO2-0 0 1, while the Pt nanoparticles loaded on TiO2-0 0 1 can more efficiently enhance the photoinduced carrier separation efficiency than that on TiO2-0 1 0, and therefore resulting in a photoactivity higher than the Pt-loaded TiO2-0 0 1. The above results provide an important indication about the effects of Pt-loading on the photocatalytic CO2 reduction activity of anatase TiO2 with different exposed facets, and shed light on the fabrication of novel nanostructured photocatalysts through morphological control for high conversion efficiency in the CO2 resource utilization.

A novel graphene-containing Li2FeSiO4 composite (Li2FeSiO4/C/G) has been synthesized successfully which shows superior performance when used as the cathode material for lithium ion batteries. The Li2FeSiO4/C precursor was synthesized via a modified sol-gel method and mixed with graphene oxide nanosheets which were then reduced by annealing to obtain electron conductive graphene. The structure characterizations by X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM) show that phase-pure Li2FeSiO4/C nanoparticles are mixed homogeneously with graphene nanosheets. When used as the cathode materials for rechargeable lithium ion batteries, the composite Li2FeSiO4/C/G shows superior large capacities and long-time cyclabilities. Specific discharge capacities of 310 mAh g−1, corresponding to 1.86 Li+ ions exchange per Li2FeSiO4 molecule, can be reached at the charging/discharging rate of 0.1 C (1 C = 166 mA g−1). At the high rate of 30 C and 50 C, the composite still shows ∼110 and ∼50 mAh g−1 discharge capacities after 1000 charging-discharging cyclings. These superior–the best up to now–performances of the composite are believed to be the cooperative result of the 3D conducting network, formed by the flexible and planar graphene nanosheets, and the nanoscale sizes of the carbon-coated Li2FeSiO4 particles.

Anatase TiO2 nanocrystals with regular polyhedron morphology and co-exposed {001} and {101} facets are prepared, and then ultrafine Ag nanoparticles (SAg NPs) with different sizes are loaded on those TiO2 facets (denoted as SAg–TiO2) through a novel in situ photoreduction approach. For comparison, Ag nanoparticles (PAg NPs) are also loaded on TiO2 facets (denoted as PAg–TiO2) by a traditional photodeposition method. The experimental results show that PAg NPs with a size of ∼20 nm only appeared on the {101} facets of TiO2, while SAg NPs with a much smaller size (1–6 nm) are highly dispersed on both {001} and {101} facets of TiO2. The size of Ag NPs plays an important role in surface plasmon resonance (SPR) effect and the photogenerated carrier separation process, and those Ag NPs loaded on TiO2 facets show size-dependent photoactivity for the RhB degradation. SAg–TiO2 with ultrafine SAg NPs on both {001} and {101} facets of TiO2 results in more substantial visible-light-responsive photoactivity and stability than PAg–TiO2 with larger Ag NPs on {101} facets of TiO2. Moreover, the RhB photodegradation reaction rate constant of SAg–TiO2 with Ag particle size of ∼1 nm is 10 and 21.3 times higher than that of PAg–TiO2 and the pristine TiO2, respectively.

BiOBr-g-C3N4 inorganic–organic composite photocatalysts were synthesized by a one-step chemical bath method at low temperature and characterized by X-ray diffraction patterns (XRD), Fourier transform infrared (FT-IR), thermo gravimetric (TG), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM) and UV–vis diffuse reflectance spectra (DRS). The BiOBr-g-C3N4 composite showed much higher visible-light-driven (VLD) photocatalytic activity than pure g-C3N4 and BiOBr for rhodamine B (RhB) degradation. The photocatalytic mechanism analysis revealed that the interreaction between BiOBr and g-C3N4 is a kind of facet coupling between BiOBr-{0 0 1} and g-C3N4-{0 0 2}. The active species trapping and quantification experiments indicated that the photoinduced charges transfer between these facets resulted in the efficient charge separation.