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ZnS nanoparticles embedded in reduced graphene oxide (RGO) were prepared via a facile microwave-assisted method and applied as anode materials of sodium-ion batteries (SIBs). The as-prepared composites exhibit excellent sodium storage properties. A maximum specific capacity of 481 mAh g −1 at the specific current of 100 mA g −1 can be achieved after 50 cycles by optimizing the RGO content in the composites. The improved sodium-ion storage ability can be ascribed to the enhanced specific surface area and increased electric conductivity due to the introduction of RGO and the decreased size of ZnS particles which can shorten the pathway of sodium-ion diffusion and facilitate the reversible Na + diffusion kinetics.

Here a facile strategy was proposed to prepare graphene (GE) sheets with unique mesoporous morphology (denoted as mGE) via a simple carbothermal reaction by using KMnO 4 as the etching agent. The morphology, structure and electrochemical properties of mGE were investigated by scanning electron microscopy, transmission electron microscopy, Raman spectra, nitrogen adsorption-desorption, cyclic voltammetry and electrochemical impedance spectroscopy. The electrosorption performance of mGE in NaCl solution was studied and compared with GE. The results show that mGE electrode exhibits a high electrosorption capacity of 6.38 mg g ⿿1 when the initial NaCl concentration is ⿼75 mg L ⿿1 and applied voltage is 1.2 V, which is about 2.3 and 1.5 times of those of GE (2.76 mg g ⿿1 ) and recently reported microporous GE (⿼4 mg g ⿿1 ), respectively, and also higher than those of other carbon materials in the literatures, due to short ion diffusion path, large accessible surface area and low charge transfer resistance offered by its novel mesoporous structure. Therefore, it is believed that mGE is a promising candidate for practical capacitive deionization applications.

Layered nickel sulfide (NS)-reduced graphene oxide (RGO) composites are prepared via a simple microwave-assisted method and subsequent annealing in N 2 /H 2 atmosphere. A detailed array of characterization tools are used to study their morphology, structure and electrochemical performance. It was found that these composites exhibit significantly improved sodium-ion storage ability as compared with pure NS under galvanostatic cycling at a specific current of 100 mA g −1 in a potential limitation of 0.005–3.0 V. Furthermore, the composite with the RGO content of 35 wt.% achieves a high maximum reversible specific capacity of about 391.6 mAh g −1 at a specific current of 100 mA g −1 after 50 cycles. These results prove that NS-RGO composites are highly promising when applied directly as anode materials in sodium-ion batteries.

In this work, porous carbon spheres with hierarchical pores (denoted as hCSs) were fabricated via a sol–gel process using a surfactant-directing assembly strategy and investigated as capacitive deionization (CDI) electrode materials for the first time. By using transmission electron microscopy and N2 adsorption/desorption analyses, a hierarchy of micropores and mesopores was demonstrated to be present in the hCSs. Based on the results of CDI measurements, the hCSs obtained at 800 °C (hCSs-800) displayed the best electrosorption performance of all the hCS samples tested: hCSs-800 exhibited a high electrosorption capacity of 15.8 mg g−1 when the initial NaCl concentration was 500 mg L−1. Furthermore, according to a Kim–Yoon plot analysis, hCSs-800 integrated the merits of both a high electrosorption capacity and fast electrosorption rate, indicating the superiority of these hCSs for CDI applications.

Sodium-ion batteries (SIBs) have attracted great interest for use as the next generation rechargeable batteries due to the abundant sodium natural resources and similar chemistry of lithium and sodium. TiO2 is an attractive candidate as an anode for SIBs due to its high safety, low cost, appropriate voltage platform and good structural stability during repeated charge–discharge processes. However, the sodium storage mechanism of TiO2 for SIBs remains unclear, which appears to be different from the working mechanism in lithium-ion batteries. This article highlights a recent report by Passerini's group, which successfully proposed a new sodium storage mechanism of TiO2 for SIBs.

TiO2 is a promising anode for sodium-ion batteries (SIBs) due to its inherent safety, low cost, good structural stability during the sodium-ion storage process and appropriate voltage platform. However, unsatisfactory electrical conductivity hinders its applications. Here we demonstrate that doping TiO2 nanotubes with Ni2+via an initial sol–gel method, subsequent hydrothermal process and final thermal treatment can balance the high conductivity and good structural stability of TiO2 to improve the sodium-ion storage performance. The resultant sample exhibits a high charge capacity of 286 mA h g−1 after 100 cycles at a current density of 50 mA g−1 and even at a high current density of 5 A g−1, a capacity of 123 mA h g−1 is maintained after 2000 cycles. It is believed that the strategy in this work can provide a useful pathway towards enhancing the electrochemical performance of TiO2 anodes for SIBs.

This study investigates the locations and interactions of adsorbed water molecules within a porous COF material, TpPa-1. The TpPa-1 samples include the as-synthesized powder samples and the samples first subjected to compression at high pressure and then ground into a powder form. The investigation applies a variety of advanced solid-state NMR techniques. The results indicate that the adsorbed water molecules in the as-synthesized and compressed samples can exist in different locations and bonding states. Here, the adsorbed water molecules in the as-synthesized samples are found to be mainly located in the pore spaces and interact only loosely with the chemical groups of the material. In contrast, a proportion of the water molecules in the compressed samples enter into the interstices between the layers and interact with the amino groups and the carbonyl groups of the material. The relocation of the water molecules in the compressed samples provides a plausible explanation for the molecular origin of the water adsorption capability of TpPa-1. In addition, the revealed weak interactions between the water molecules and the chemical groups of TpPa-1 are correlated with the molecular origin of the high water permeance.

Capacitive deionization (CDI) is regarded as a novel, low-cost, and environmentally friendly technique that plays a critical role in desalination and water treatment. Although much progress has been achieved, the development of better CDI technologies, especially through the design and synthesis of various porous carbonaceous materials with enhanced CDI performance, continues to attract increasing interest within the scientific fraternity. Considering that previous traditional porous carbons might suffer from deficient salt adsorption capacity, the nitrogenization of porous carbons, which brings new opportunities for CDI applications, has emerged as an effective strategy to modify the surface characteristics of porous carbons and ultimately improve their CDI performance. This review summarizes the recent significant breakthroughs on the construction of NCs, including in situ doping and post-treatment strategies, and their practices in the field of CDI to impart a comprehensive understanding of the strategic evolution of the synthetic approaches to nitrogen-doped carbons (NCs) with remarkable CDI characteristics. We present an exhaustive analysis of newly synthesized NCs and the impact of their compositional and structural features on their CDI performance; further, we highlight a special emphasis on the possible role of nitrogen dopants in the CDI process. In addition to elucidating the state-of-the-art CDI applications, we address the remaining challenges, and finally, the possible direction for the use of NCs for CDI is described to provide some useful clues for future developments in this promising field.

With the development of flexible wearable electronic devices, energy storage equipment like supercapacitor with high energy density, good mechanical properties and safety has attracted more and more attention. However, the currently existing energy storage materials normally suffer from several drawbacks, such as poor flexibility, hidden danger, toxicity and especially low energy density, limiting their practical applications. Expanding the voltage window by employing the hydrogel electrolyte is regarded as an effective method to improve the energy density of supercapacitor. Herein, we employ a zwitterionic natural polymer hydrogel with excellent mechanical strength and flexibility as electrolyte to assemble a solid-state zinc-ion hybrid supercapacitor (H-ZHS) with Zn foil and activated carbon electrode. The H-ZHS exhibits an amazingly wide and stable voltage window of 2.4 V, high maximum energy density of 286.6 Wh kg−1 at the power density of 220 W kg−1 and superior capacity retention of 95.4% after 2000 cycles at 2 A g−1 calculated based on mass of activated carbon electrode. The strategy in this work should provide a new insight in exploring zinc-ion hybrid supercapacitor with high energy density for flexible wearable electronic devices.

The design of new-family carbon materials to capture more saline ions is one of the biggest challenges of capacitive deionization (CDI) for water desalination. Herein, we demonstrate the preparation of integrated tubular metal-organic framework architectures using a 3D scaffold, and their derivative of nitrogen-doped carbon tubes (denoted as NCTs) that possess a maximum salt adsorption capacity of 56.9 mg g−1 and good cycling stability. Compared with other carbon materials, our elaborately designed NCTs exhibit multiple advantages: (i) tubular architecture diminishes the efficient diffusion distance for both electrons and ions, (ii) binder-free electrode configuration provides increased accessible surface area for ions accommodation, and (iii) plentiful nitrogen dopants improve the reactivity and electrical conductivity of carbon matrix. Consequently, NCTs exhibit an ultrahigh CDI performance compared to other carbon materials reported previously, highlighting the significance of 3D free-standing carbon architectures for CDI application.

Carbon coated CoP hollow spheres (CoP/C) were prepared from cobalt-based MOFs via simple calcining and subsequent phosphorization process. Meanwhile, N-doped carbon shells were also synthesized by a low-cost hard-templating method. Both of the obtained CoP/C and N-doped carbon shells deliver remarkable specific capacitances and excellent capacitance retentions when used as electrodes for supercapacitor. Remarkably, the asymmetric supercapacitor device based on the CoP/C and N-doped carbon shells delivers a high energy density of 16.14 Wh kg−1 at a power density of 700 W kg−1 and outstanding cycling stability (99.5% capacitance retention after 5000 cycles at a current density of 7 A g−1). CoP/C should be a promising electrode material for next-generation supercapacitor application.

Currently, limited charge efficiency and poor long-term desalination stability remain the major challenges for the practical application of membrane-free capacitive deionization (CDI). Hybrid capacitive deionization (HCDI) is suggested to effectively address these issues. Although cathode-hybridized HCDI has been studied widely, anode-hybridized HCDI has been seldom reported to date. In this work, a radical polymer, poly (2,2,6,6-tetramethylpiperidinyloxy methacrylate) (PTMA), with good anion-storage capability was used as the anode of the membrane-free HCDI (denoted as A-HCDI) for the first time. PTMA restrains the undesirable faradaic reactions that occur on the conventional carbon anodes and suppresses the cation expulsion effect that dominates the charging process of the carbon anode after the long-term oxidation, degrading the membrane-free CDI process. Compared with AC anode, PTMA anode improves the average charge efficiency from 18.7% to 48.6% in the first 20 cycles at 1.2 V. Moreover, A-HCDI exhibits a long-term stable salt removal capacity of 13.9 mg g−1 during charging/discharging at 1.2/0 V for 500 h, while membrane-free CDI only remains effective before 70 h. The novel A-HCDI provides a new approach for efficient and stable membrane-free electrochemical desalination.

Nowadays, Ti3C2Tx MXene has been reported to afford an ideal platform for the growth of TiO2 by oxidation. Unfortunately, the TiO2 derived from Ti3C2Tx still possesses low lithium ion diffusion coefficient, poor electrical conductivity and relatively inferior capacity when used as anode of rechargeable lithium ion batteries (LIBs). In this work, three dimensional (3D) TiO2@nitrogen-doped carbon (NC)/Fe7S8 composite was fabricated by a facile and simple hybrid strategy via in situ polymerization of pyrrole monomer with alkalized Ti3C2Tx and subsequent vulcanization at 700 °C. When evaluated as an anode material for LIBs, the TiO2@NC/Fe7S8 demonstrates a high reversible capacity (516 mAh g−1 after 100 cycles at 0.1 A g−1), excellent rate capability (337 mAh g−1 at 1 A g−1) and robust long cycling stability (282 mAh g−1 after 1000 cycles at 4 A g−1). The excellent electrochemical performances are contributed by the unique architecture of TiO2@NC/Fe7S8, where 3D urchin-like TiO2 with good structural stability provides adequate space to increase the contact between electrode and electrolyte, shorten the lithium ion diffusion length and alleviate the volume change; nitrogen-doped carbon shell layer improves the electrical conductivity, facilitates the electron transport and prevents the aggregation for Fe7S8; Fe7S8 contributes high specific capacity during charge/discharge process. Importantly, the hybrid approach in this work enlightens the exploration on combing the MXene-derived oxides with other metal sulfides for promising applications in energy storage field.

The combination of transitional metal dichalcogenides with MXene is an effective strategy to explore high-performance anode materials for lithium-ion batteries (LIBs). In this work, SnS2/Sn3S4 hybrid decorated on Ti3C2 MXene (S-TC) was prepared through a facile solvothermal and calcination process. The multi-layered Ti3C2 matrix improves the electron transport capability, inhibits the aggregation and accommodates the volume change of SnS2/Sn3S4 hybrid, while the SnS2/Sn3S4 hybrid confined in the multilayer stacks serves as a spacer to decrease the tendency of layer restacking and improves the limited capacities of Ti3C2. Besides, the nano-sized SnS2/Sn3S4 hybrid with high specific surface area also enhances the contact between electrolyte and electrode. When used as anode for LIBs, S-TC demonstrates a good cycling stability (462.3 mAh g−1 at 100 mA g−1 after 100 cycles) and superior rate performance (216.5 mAh g−1 at 5000 mA g−1). The strategy in this work should provide a new insight into fabricating novel MXene-based anode material for high-rate LIBs.

Covalent organic frameworks (COFs) with devisable nanostructures have exhibited extensive application prospects in energy storage and conversion. In this work, spherical COFs were successfully utilized as an ideal precursor for N, B co-doped carbon spheres (NBCs) that display hierarchical spherical architectures with rich pores. When applied as lithium ion batteries (LIBs) anode, NBCs exhibit high reversible specific capacity and outstanding long-life cycling stability (205.5 mAh g−1 at 5.0 A g−1 and 171.4 mAh g−1 at 10.0 A g−1 after 5000 cycles) owing to their hierarchical porosity, unique structure and in-situ N, B co-doping. The excellent lithium storage ability, especially satisfactory long cycling stability, enables NBCs to be a promising candidate for LIBs.

Wearable strain sensors based on nanomaterial/elastomer composites have potential applications in flexible electronic skin, human motion detection, human–machine interfaces, etc. In this research, a type of high performance strain sensors has been developed using fragmentized carbon nanotube/polydimethylsiloxane (CNT/PDMS) composites. The CNT/PDMS composites were ground into fragments, and a liquid-induced densification method was used to fabricate the strain sensors. The strain sensors showed high sensitivity with gauge factors (GFs) larger than 200 and a broad strain detection range up to 80%, much higher than those strain sensors based on unfragmentized CNT/PDMS composites (GF < 1). The enhanced sensitivity of the strain sensors is ascribed to the sliding of individual fragmentized-CNT/PDMS-composite particles during mechanical deformation, which causes significant resistance change in the strain sensors. The strain sensors can differentiate mechanical stimuli and monitor various human body motions, such as bending of the fingers, human breathing, and blood pulsing.

Capacitive deionization (CDI) aims to sequester ionic species in an electrochemical double layer that forms at the interface between the solution and porous electrode, therefore resulting in desalination, in which the porous electrode as the ion accumulation accepter plays a vital role during adsorption. Generally, the electrode is made of porous materials with high specific surface area and superior conductivity, both of which will be of great advantage in absorbing large quantities of salt ions for desalination. Carbons, due to their good electrical conductivity, high surface area, and low cost, are considered to be the most promising materials for CDI. In recent years, most reports of CDI studies typically utilized various carbon materials with high specific area. In this chapter, carbon materials and their nitrogen-doped partners are discussed in detail.

TiO2-reduced graphene oxide (RGO) composite was synthesized via a sol-gel process and investigated as an anode material for sodium-ion batteries (SIBs). A remarkable improvement in sodium ion storage with a reversible capacity of 227 mAh g−1 after 50 cycles at 50 mA g−1 is achieved, compared to that (33 mAh g−1) for TiO2. The enhanced electrochemical performance of TiO2-RGO composite is attributed to the larger specific surface area and better electrical conductivity of TiO2-RGO composite. The excellent performance of TiO2-RGO composite enables it a potential electrode material for SIBs.

We synthesized the Ag 2 O/F-TiO 2 composites via an aqueous precipitation method and characterized their morphology, structure and photocatalytic activity in the degradation of methylene blue (MB) using scanning electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, UV–vis absorption spectroscopy, and electrochemical impedance spectra, respectively. The results show that the Ag 2 O addition could enhance the visible light photocatalytic activity of Ag 2 O/F-TiO 2 composites with a maximum MB degradation rate of 93% for 60 min, much higher than that of the F-TiO 2 (30%). The excellent photocatalytic activity is due to the increased visible light absorption, and promoted separation of photo-generated electrons and holes in F-TiO 2 with the introduction of Ag 2 O.

MgFe2O4/reduced graphene oxide composites (MFO/RGO) were prepared via a facile microwave assisted reduction of graphene oxide in MFO precursor solution, and used as anode materials for sodium ion batteries (SIBs). Their morphology, structure and electrochemical performance were characterized by field emission scanning electron microscopy, transmission electron microscopy, X-ray diffraction, nitrogen adsorption-desorption isotherms, galvanostatic charge/discharge tests, cyclic voltammetry and electrochemical impedance spectroscopy, respectively. The results show that MFO/RGO composite with 20 wt.% RGO exhibits a maximum reversible capacity of about 347.5 mAh g−1 at 50 mA g−1 after 70 cycles with good cycling stability. The excellent electrochemical performance of MFO/RGO composites should be attributed to the synergistic effect of MFO and RGO to form a porous conductive network structure which offers the increased specific surface area, the facilitated electron transfer ability and the effective buffering of volume expansion.

Mesoporous yolk-shell structure Bi 2 MoO 6 (BMO-YS) microspheres were successfully synthesized via a facile solvothermal route in Bi 2 MoO 6 precursor solution. The morphology, structure and photocatalytic performance of the BMO-YS in the degradation of Rhodamine B (RhB) were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, nitrogen adsorption–desorption, UV–vis absorption spectroscopy and electrochemical impedance spectra, respectively. The as-prepared BMO-YS mainly consists of microspheres with diameters of about 1.5 μm. The photocatalytic studies reveal that the BMO-YS not only exhibits optimum photocatalytic performance, which may be attributed to the excellent charge separation characteristics and the enhanced light absorption offered by its unique yolk-shell structure, but also possesses excellent recyclability for photocatalysis.

GeO 2 -reduced graphene oxide (RGO) composites were prepared by a simple freeze-drying method. After thermal annealing in N 2 atmosphere at 450 °C for 2 hours, the composites were examined as anode materials of sodium ion batteries for the first time. Their morphology, structure and electrochemical performance were characterized by field-emission scanning electron microscopy, X-ray diffraction, N 2 adsorption-desorption isotherm, cyclic voltammetry and electrochemical impedance spectroscopy, respectively. A maximum specific capacity of 330 mAh g −1 can be achieved after 50 galvanostatic charge-discharge cycles at a current density of 100 mA g −1 by tuning the RGO content in the composites. Even after 650 cycles at a high current density of 1 A g −1 , the specific capacity can still maintain at 153.7 mAh g −1 , demonstrating the excellent Na ion storage properties of the GeO 2 -RGO composites.

Bi2O3–Ag2O hybrid photocatalysts were successfully synthesized via a co-precipitation method. The morphology, structure and photocatalytic performance in the degradation of phenol were characterized by using scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction, electrochemical impedance spectra and UV–vis absorption spectroscopy, respectively. The results show that Bi2O3–Ag2O hybrid photocatalysts exhibit enhanced photocatalytic performance in the degradation of phenol with a maximum degradation rate of 92% for 60 min under visible light irradiation compared with pure Bi2O3 (57%), which is ascribed to the increase in light adsorption and the reduction in electron–hole pair recombination with the introduction of Ag2O.

The yolk-shell structure Bi(4-2x)Mo(x)O6 (x⩽1) microspheres were successfully synthesized via a simple solvothermal method. The morphology, structure and photocatalytic performances of the samples in the degradation of rhodamine B (RhB) and methyl orange (MO) were characterized by X-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy, X-ray diffraction, UV-vis absorption spectroscopy and electrochemical impedance spectra, respectively. The results show that the yolk-shell structure Bi(2.38)Mo(0.81)O6 microspheres exhibit the best photocatalytic performance for the degradation of RhB and MO with a degradation rate of 99% and 72% under visible light irradiation.

Fe 2 O 3 -reduced graphene oxide (RGO) composites were successfully fabricated via a facile microwave-assisted reduction of graphite oxide in Fe 2 O 3 precursor solution using a microwave system, and investigated as anode material for sodium ion batteries (SIBs). Their morphologies, structures and electrochemical performance were characterized by transmission electron microscopy, X-ray diffraction, Raman spectroscopy, cyclic voltammetry and electrochemical impedance spectroscopy, respectively. The results show that the RGO addition can enhance the electrochemical performance of Fe 2 O 3 -RGO composites. Fe 2 O 3 -RGO composite with 30 wt.% RGO exhibits a maximum reversible capacity of 289 mA h g −1 at a current density of 50 mA g −1 after 50 cycles and excellent rate performance due to the synergistic effect between Fe 2 O 3 and RGO. The high capacity, good rate capability and excellent cycle performance of Fe 2 O 3 -RGO composites enable them a potential electrode material for SIBs.

Carbon microspheres (CSs) were successfully fabricated and used as counter electrodes of dye-sensitized solar cells (DSSCs). CSs were obtained through a fast microwave-assisted approach using sucrose as the precursor in a microwave system and subsequent thermal treatment at 600, 800 and 1000 °C. A maximum photovoltaic conversion efficiency of 5.5% is achieved for DSSCs based on the CSs counter electrodes, which is comparable to the cell based on conventional Pt counter electrode at one sun (AM 1.5 G, 100 mW cm−2). The results suggest the CSs to be a potential candidate for counter electrodes of DSSCs.

Highly conductive, crystalline, polymer electrolytes, β-cyclodextrin (β-CD)-polyethylene oxide (PEO)/LiAsF6 and β-CD-PEO/NaAsF6 , were prepared through supramolecular self-assembly of PEO, β-CD, and LiAsF6 /NaAsF6 . The assembled β-CDs form nanochannels in which the PEO/X(+) (X=Li, Na) complexes are confined. The nanochannels provide a pathway for directional motion of the alkali metal ions and, at the same time, separate the cations and the anions by size exclusion.

Nitrogen-doped porous carbon spheres (NPCSs) were prepared through a fast microwave-assisted approach using sucrose as the precursor in a microwave system and subsequent thermal treatment in ammonia atmosphere at different temperatures. The morphology, structure and electrochemical performance of the NPCSs were characterized by scanning electron microscopy, nitrogen adsorption-desorption, X-ray photoelectron spectroscopy, cyclic voltammetry and electrochemical impedance spectroscopy, and their electrosorption performance in NaCl solution was studied. The results show that NPCSs treated at 1000 °C exhibit an extremely high electrosorption capacity of 14.91 m g g−1 when the initial NaCl concentration is 1000 mg l−1, which shows great improvement compared with their undoped counterpart. The nitrogen doping is suggested to be a very effective method to improve the electrosorption performance, and the NPCSs should be a very promising candidate as electrode material for CDI application.

Capacitive deionization (CDI) is an emerging technology offering a green and efficient route to obtain clean water. Up to now, the key of CDI technology has been focused on the exploration of electrode materials with a rationally designed structure and excellent performance, because the electrosorption performance of the carbon-based electrodes reported to date cannot meet the demands of practical applications of CDI. Herein, novel graphene/carbon nanotubes (CNTs) hybrid sponge (GNS) structures were designed and fabricated via directly freeze-drying graphene oxide/CNTs mixed solution followed by annealing in nitrogen atmosphere. The morphology, structure and electrochemical performance of GNS were characterized by scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, nitrogen adsorption–desorption, cyclic voltammetry and electrochemical impedance spectroscopy. The results show that GNS with 20 wt% CNTs has a maximum specific surface area of 498.2 m2 g−1 and a highest specific capacitance of 203.48 F g−1 among all the samples. When used as CDI electrode, it exhibits an ultrahigh electrosorption capacity of 18.7 mg g−1, and, to our knowledge, this value is superior to those of other carbon electrodes reported recently. GNS should be a promising electrode material for high-performance CDI.

Porous CuO/Cu2O composite hollow octahedrons were synthesized simply by annealing Cu-based metal-organic framework templates. When evaluated as anode materials for sodium ion batteries, they exhibit a high maximum reversible capacity of 415 mA h g(-1) after 50 cycles at 50 mA g(-1) with excellent cycling stability and good rate capability.

Ultra-thin carbon nanofiber networks (bc-CNFs) were prepared from natural-based bacterial cellulose pellicle through freeze drying and subsequent carbonization at different temperatures. The morphology, structure and electrochemical performance of the bc-CNFs were characterized by field emission scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, nitrogen adsorption–desorption, Fourier transform infrared spectroscopy, cyclic voltammetry and electrochemical impedance spectroscopy. Their electrosorption performance in NaCl solution was studied and compared with those of carbon nanotubes (CNTs) and electrospun carbon nanofibers (e-CNFs). The results show that the bc-CNFs treated at 800 °C exhibited excellent desalination performance with an electrosorption capacity of 12.81 mg g−1 in 1000 mg l−1 NaCl solution, much higher than those of the CNTs (3.78 mg g−1) and the e-CNFs (6.56 mg g−1). The excellent performance of the bc-CNFs is ascribed to their high specific surface area, low charge transfer resistance and superior hydrophility.

Mesoporous nanostructured Co3O4 was prepared by the direct pyrolysis of a Co-based metal organic framework (MOF) template at a relatively low temperature rather than a high temperature. When tested as an anode material for lithium-ion batteries (LIBs), this porous Co3O4 exhibited a greatly enhanced performance of lithium storage. The capacity of the porous Co3O4 retained 913 mA h g−1 after 60 cycles at a current rate of 200 mA g−1. Excellent rate capability was also achieved. We also found out that the Co3O4 prepared from the MOF template at a relatively low temperature has better electrochemical performance than that prepared at high temperature.

A nitrogen-doped electrospun reduced graphene oxide–carbon nanofiber composite (NG–CNF) was fabricated via electrospinning by adding graphite oxide into a precursor solution and subsequent thermal treatment under an ammonia atmosphere. The morphology, structure and electrochemical performance of the composite were characterized by scanning electron microscopy, nitrogen adsorption–desorption, cyclic voltammetry and electrochemical impedance spectroscopy, and their capacitive and electrosorption performances in NaCl solution were studied. The NG–CNF composite electrode shows excellent specific capacitance (337.85 F g−1) and electrosorption capacity (3.91 mg g−1), much higher than those of pure carbon nanofibers (171.28 F g−1 and 3.13 mg g−1) and the reduced graphene oxide–carbon nanofiber composite (264.32 F g−1 and 3.60 mg g−1). The enhanced performance of the NG–CNF is ascribed to the nitrogen doping and the formation of an effective “plane-to-line” conducting network in the composite, which facilitates the electron transfer and ion transport as well as increases the specific surface area.

Porous carbon spheres (PCSs) were fabricated through a fast microwave-assisted approach using sucrose as the precursor in a microwave system and subsequent thermal treatment at 600, 800 and 1000 °C. The morphology, structure and electrochemical performance of the PCSs were characterized by scanning electron microscopy, Raman spectroscopy, nitrogen adsorption-desorption, cyclic voltammetry and electrochemical impedance spectroscopy. Their electrosorption performance in NaCl solution was studied and compared with activated carbon, carbon nanotubes, reduced graphene and carbon aerogels. The results show that due to their high specific surface area and low charge transfer resistance, PCSs treated at 1000 °C exhibit high electrosorption capacity of 5.81 m g g−1 when the initial solution concentration is 500 mg l−1, which is higher than those of other carbon materials.

Semiconductor photocatalysis has attracted tremendous attention due to its potential in environmental remediation, clean energy production and chemical reaction technology. Pursuing high efficiencies is a core task in the field. One of the major factors in photocatalysis is the limited light absorption of photocatalysts in the incident solar spectrum. In this treatise, we will survey recent advancements in light-conversion phosphor-based composites including up-conversion, down-conversion, and long afterglow phosphor-based composites for photocatalysis.

Nitrogen-doped carbon nanorods (NCNRs) were prepared from naturally based nanocrystalline cellulose through simple freeze drying and subsequent thermal treatment under an ammonia atmosphere at different temperatures. The morphology, structure and electrochemical performance of the NCNRs were characterized using scanning electron microscopy, transmission electron microscopy, nitrogen adsorption–desorption, X-ray photoelectron spectroscopy, cyclic voltammetry and electrochemical impedance spectroscopy, and their electrosorption performance in NaCl solution was studied. The results show that NCNRs treated at 1000 °C exhibit an extremely high electrosorption capacity of 17.62 mg g−1 when the initial NaCl concentration is 500 mg l−1, which shows great improvement compared with their undoped counterparts. The nitrogen doping proved to be a very effective method for improving the electrosorption performance, and the NCNRs should be very promising candidates as electrode materials for CDI applications.

MoS2-reduced graphene oxide (RGO) composites were synthesized via a facile microwave assisted reduction of graphene oxide in MoS2 precursor solution and subsequent annealing in N2/H2 atmosphere at 800 °C for 2 h. Their morphology, structure and electrochemical performance were characterized by field-emission scanning electron microscopy, transmission electron microscopy, X-ray diffraction, Raman spectroscopy, N2 adsorption-desorption isotherm, cyclic voltammetry and electrochemical impedance spectroscopy. The MoS2-RGO composites with different RGO loadings were applied as anode materials of sodium ion batteries (SIBs) and they exhibit a maximum reversible specific capacity of about 305 mAh g−1 at a current density of 100 mA g−1 after 50 cycles and excellent rate performance. The results demonstrate that MoS2-RGO could be a potential electrode material for rechargeable SIBs.

Carbon sphere (CS)@Bi2MoO6 core–shell structure (CS@BMO) composites were successfully synthesized via a solvothermal reaction of CSs and Bi2MoO6 precursors in the mixed solution of ethylene glycol and ethanol. The morphology, structure and photocatalytic performance of the composites in the degradation of Rhodamine B (RhB) were characterized by scanning electron microscopy, X-ray diffraction, UV-vis absorption spectroscopy, electrochemical impedance spectra and nitrogen adsorption–desorption, respectively. The results show that the CS@BMO composites exhibit enhanced photocatalytic performance for degradation of RhB with a maximum degradation rate of 95% under visible light irradiation compared with the pure Bi2MoO6. The improved photocatalytic performance is ascribed to the enhanced specific surface area and light absorption as well as the reduced electron–hole pair recombination with the presence of CSs in the composites.

Water-dispersed CdSe/CdS/ZnS core/shell/shell quantum dots (QDs) with the highest quantum yield of 25.4% were first synthesized for each component by microwave irradiation. As-prepared QDs do not only possess a large Stokes shift but also exhibit excellent repeatability. They can convert near UV and blue light with lower sensitivity to the Si solar cell to red light at which the solar cell has higher sensitivity. The fabricated CdSe/CdS/ZnS QDs/SiO2 composite films were applied to Si solar cells as luminescent down-shifting layers and the effect of QDs on the photoelectric conversion efficiency of photovoltaic modules was investigated. Under one sun illumination, the composite film containing an appropriate amount of CdSe/CdS/ZnS QDs effectively enhances the photoelectric conversion efficiency of the Si solar cell by spectral down-shifting as compared to the bare glass substrate, and the maximum achieves 16.14%.

Recently sodium ion batteries (SIBs) as a new energy storage system have attracted enormous interests. Unfortunately, the development of high-performance electrode materials for SIBs is restricted owing to the large volume change during sodium insertion and extraction. In this work, porous CoFe

It is still a great challenge to develop efficient semiconductive photocatalysts responding to visible light radiation. We show an efficient ZnIn2S4/UiO-66 hybrid photocatalysts with flowerlike 3D microspheres synthesized via a facile solvothermal method. A 20 wt.% UiO-66 emersion raises the Cr(VI) reduction rate up to 99% and higher after 60 min visible light irradiation. The substantial enhancement of photocatalytic and photoelectronchemical activity of pure ZnIn2S4 by UiO-66 addition is attributed to the ZnIn2S4/UiO-66 interfacial charge transferring and more active sites for pollute adsorption.

F-doped TiO 2 (F-TiO 2 ) were successfully synthesized using a modified sol–gel method. The morphologies, structures, and photocatalytic performance in the degradation of methylene blue (MB) were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, UV–vis absorption spectroscopy, and electrochemical impedance spectra, respectively. The results show that F-TiO 2 exhibits an enhanced photocatalytic performance in the degradation of MB with a maximum degradation rate of 91% under visible light irradiation as compared with pure TiO 2 (32%). The excellent photocatalytic activity is due to the contribution from the increased visible light absorption, promoted separation of photo-generated electrons and holes as well as enhanced photocatalytic oxidizing species with the doping of F in TiO 2 .

Carbon nanorods (CNRs) were fabricated from natural based nanocrystalline cellulose through a simple thermal treatment at 800, 1000 and 1200 °C. The morphology, structure and electrochemical performance of CNRs were characterized by atomic force microscopy, Raman spectroscopy, nitrogen adsorption–desorption, cyclic voltammetry and electrochemical impedance spectroscopy. Their electrosorption performance in NaCl solution was studied. The results show that CNRs treated at 1200 °C exhibit the highest specific capacitance of 264.19 F g−1 and electrosorption capacity of 15.12 mg g−1 with the initial NaCl concentration of 500 mg l−1, due to their high specific surface area and low charge transfer resistance.

Long afterglow Sr4Al14O25:Eu,Dy phosphors were introduced into the TiO2 photoanode of CdS quantum dot-sensitized solar cells (QDSSCs) as both a scattering and down converting layer, and the photovoltaic performances of the cells were investigated. The results show that the cell with Sr4Al14O25:Eu,Dy achieves a power conversion efficiency of 1.40%, which is an increase of 38% compared to the cell without Sr4Al14O25:Eu,Dy (1.02%). The performance improvement is attributed to enhanced light harvesting via improved light absorption and scattering processes. After a single sun illumination for 1 min and subsequent removal of the light source, the cell with Sr4Al14O25:Eu,Dy could be driven even in the dark by the long persistent light from Sr4Al14O25:Eu,Dy.

A modified membrane capacitive deionization (m-MCDI) device was proposed with high desalination efficiency. The m-MCDI electrodes were fabricated by introducing the anion exchange polymer (dimethyl diallyl ammonium chloride) and cation exchange (polyethyleneimine) polymer into carbon nanotubes (CNTs) electrodes and their desalination performance in NaCl solutions was investigated. The m-MCDI unit cell based on both anion and cation exchange polymers exhibits a high NaCl removal of 93%, much higher than that of conventional capacitive deionization cell with CNTs electrode (25%) or MCDI cell with commercial anion and cation exchange membranes (74%) in a certain experiment at 1.2 V and for an initial conductivity of 50 μS/cm. The large improvement in desalination performance is mainly due to the reduced co-ion expulsion effect by introducing ion exchange polymers and the better contact adhesion between ion exchange polymers and electrodes than between commercial ion exchange membranes and electrodes.

CdSe quantum dot-sensitized solar cells based on an efficient bifunctional structured layer composed of long afterglow SrAl 2 O 4 :Eu,Dy phosphors on top of a transparent layer of nanocrystalline TiO 2 were fabricated and their photovoltaic performances were investigated. The results show that a high power conversion efficiency of 1.22% is achieved for the cell with SrAl 2 O 4 :Eu,Dy at one sun illumination (AM 1.5 G, 100 mW cm −2 ), which is an increase of 48% compared to the cell without SrAl 2 O 4 :Eu,Dy (0.82%). After one sun illumination for 1 min and subsequent turn off of the light source, the cell with SrAl 2 O 4 :Eu,Dy still shows an efficiency of 0.04% under dark condition due to the irradiation by the long persistent light from SrAl 2 O 4 :Eu,Dy. The present strategy should provide a possibility to fulfill the operation of solar cells even in the dark.