•The growth of C3N4 nanosheets on carbon-fiber (CF) cloth has been realized.•CF/C3N4 cloth exhibits excellent flexibility, strong visible-light photocatalytic activity.•CF/C3N4 cloth can be used as filter-membrane for degrading the flowing wastewater.•The dominant active species are superoxide and the photogenerated holes.•CF/C3N4 cloth can be easily recycled and remains good stability.For degrading the flowing wastewater, the ideal photocatalysts should be nanostructured filter-membrane with large area, excellent flexibility and high visible-light-driven photocatalytic activity. Herein, we report the design and preparation of C3N4 nanosheets on carbon-fiber (CF) cloth as filter-membrane-shaped photocatalyst. The growth of C3N4 nanosheets has been realized by using a dip-coating and thermal condensation method with carbon-fiber cloth as the substrate. The resulting cloth (area: 4 × 4 cm2) is composed of carbon fiber (diameter: 15 μm) bunches which are decorated with C3N4 nanosheets with the thickness of 30 nm. CF/C3N4 cloth exhibits excellent flexibility and strong visible-light absorption at ∼450 nm. When CF/C3N4 cloth (area: 4 × 4 cm2) is floated on the polluted water, it can degrade 98% Rhodamine B (RhB) in 60 min and 99.3% colorless parachlorophenol (4-CP) after 120 min of visible-light irradiation. Interestingly, when CF/C3N4 cloth (area: 4 × 4 cm2) as the filter-membrane is used to construct a new photocatalytic setup for degrading the flowing wastewater (rate: 1.5 L h−1) under visible-light irradiation, the degradation efficiency of RhB goes up from 18% to 92% with the increase of filtering/degrading grade from 1 to 7. Direct contact between CF/C3N4 cloth and pollutants is found to be unnecessary for the efficient degradation. Furthermore, free radical capture experiments confirm that both O2− and h+ play a major role in the system under visible light irradiation; and CF/C3N4 cloth exhibit excellent stability. Therefore, CF/C3N4 cloth has great potential to be used as an efficient, stable, macroscale filter-membrane-shaped photocatalyst for degrading the flowing wastewater.Download high-res image (195KB)Download full-size image

Conventional wide bandgap semiconductors can absorb UV/visible light but have no photoabsorption band in the near-infrared (NIR) region, leading to difficulty in their use as NIR-responsive agents. With TiO2 as an example, we report the tuning from UV-responsive TiO2 nanocrystals to blue TiO2 nanocrystals with newly appeared NIR absorption band through the Nb-doping strategy. A strong NIR band should result from the localized surface plasmon resonances due to the considerable free electrons originating from the efficient incorporation of Nb5+ ions (<15.5%). Interestingly, under the irradiation of a 1064 nm laser, Nb-doped TiO2 nanocrystals can convert laser energy into heat, and higher Nb-doping content can lead to higher NIR-induced temperature elevation, highlighting that the photothermal performances of TiO2 nanocrystals can be dynamically modulated by adjusting the Nb-doping levels. After coating with PEGylated phospholipid, the resulting nanocrystals display water dispersibility, high photothermal conversion efficiency and cytocompatibility. Therefore, these Nb-doped TiO2 nanocrystals can be used as efficient and heavy-metal-free nanoagents for the simultaneous NIR/photoacoustic imaging and photothermal therapy of tumors using a 1064 nm laser in the second biological window.

•Hydrophilic (NH4)xWO3-PEG nanorods have been prepared.•(NH4)xWO3-PEG nanorods exhibit strong NIR absorption and photothermal effects.•(NH4)xWO3-PEG nanorods have strong X-ray attenuation ability for CT imaging.•Cancer cells in vivo can be destroyed by the photothermal effects.The simultaneous imaging and photothermal therapy of tumors have attracted much attention, and a prerequisite is to obtain multifunctional nanomaterials. Ideally, one kind of nanoparticles with single component can be used as both imaging agent and photothermal agent. Herein, we have developed the PEGylated (NH4)xWO3 (denoted as (NH4)xWO3-PEG) nanorods as multifunctional nanoparticles with single semiconductor component. (NH4)xWO3-PEG nanorods with about 30 nm diameter and length of several hundred nanometers have been obtained through a solvothermal synthesis—PEGylation two-step route. Under the irradiation of 980-nm laser with intensity of 0.72 W cm− 2, aqueous dispersion of (NH4)xWO3-PEG nanorods (0.67–5.44 mmol/L) displays high elevation (17.6–34.5 °C) of temperature in 400 s, accompanied by an excellent long-term photothermal stability. Furthermore, (NH4)xWO3-PEG nanorods exhibit as high as 6 times X-ray attenuation ability compared to that of the clinically used iodine-based X-ray computed tomography (CT) contrast agent (Iopromide). More importantly, after PBS solution of (NH4)xWO3-PEG nanorods is injected into the tumor of mice, the tumor can be effectively detected by CT imaging. Moreover, cancer cells in vivo can be further destroyed by the photothermal effects of (NH4)xWO3-PEG nanorods, under the irradiation of 980-nm laser with the safe intensity of 0.72 W cm− 2 for 10 min. Therefore, (NH4)xWO3-PEG nanorods can be used as a new kind of stable and efficient multifunctional nanoagent with single component for simultaneous CT imaging and photothermal therapy of tumor.Download high-res image (129KB)Download full-size image

One of the prerequisites for the development of wireless nanobiodevices (such as nanorobots) is to utilise an in vivo energy source as a biopower component that is continuously available in the operational biological environment. To address this problem, herein we have developed a new model of a 980-nm laser driven photovoltaic cell (hereafter abbreviated as 980LD-PC) by incorporating a flexible up-converting luminescent film and flexible amorphous silicon thin film photovoltaic cell. NaYF4:Yb,Er-PET composite films are prepared by using film casting technology, and they exhibit excellent up-converting luminescence, flexibility and transparency. Subsequently, the composite film with NaYF4:Yb,Er/PET weight ratio of 20% is adhered on the surface of a flexible amorphous silicon film solar cell for constructing a flexible 980LD-PC photovoltaic cell. Under the irradiation of a 980-nm laser (intensity: 720 mW cm−2, area: 0.25 cm2) that is slightly lower than the conservative limit (726 mW cm−2) for human skin exposure, the resulting 980LD-PC exhibits strong up-converting luminescence, and it has a maximal electrical output of 94 μW. More importantly, after being covered with a layer of chicken skin (thickness: ca. 1 mm) as a model of biological tissue, 980LD-PC still exhibits bright up-converting luminescence and a maximal electrical output of 62 μW which is high enough to drive biological devices including in vivo nanorobots (power: at least 1 μW) and cardiac pacemakers (power: about 10 μW). This research paves the way for the development of novel flexible biopower sources to drive wireless nanobiodevices and other biodevices implanted under the human skin.

The selective shielding of solar light has drawn much attention for the application of innovative energy-saving windows, and a prerequisite for development is obtaining cost-efficient optical materials and coatings which can transmit visible light but cut off near-infrared (NIR) light. In the present work, we have developed low-cost CuS nanoplates as a novel kind of NIR shielding material. CuS nanoplates with a size of 150–250 nm and a thickness of about 30 nm are synthesized by a simple hydrothermal route, and they exhibit weak absorption in the visible region but strong absorption in the NIR region due to their localized surface plasmon resonances. Subsequently, CuS nanoplates are further mixed with polydimethylsiloxane (PDMS) to fabricate CuS/PDMS films. These flexible films retain good transparency in the visible region and strong absorption in the NIR region. For example, a 0.8 mm-thick CuS/PDMS film with 0.10 wt% CuS can transmit 63.0% visible light (400–780 nm) but shield 78.1% NIR light (780–2500 nm). With this film-coated glass as a window of the sealed black box, the interior air temperature of the box goes up from room temperature of 23.0 °C to ∼27.7 °C in 1500 s under the irradiation of strong solar light with an intensity of 0.5 W cm−2, and the temperature elevation (ΔT = 4.7 °C) is much lower compared with that observed with a glass slide (ΔT = 13.7 °C) or ITO glass (ΔT = 9.3 °C) as the window under identical conditions. These facts confirm that the CuS/PDMS film can efficiently prevent the elevation of room temperature, due to its excellent NIR shielding properties. Therefore, CuS nanoplates have great potential as novel NIR shielding materials for the design and development of cost-efficient optical coatings as innovative energy-saving windows in modern buildings and vehicles.

•BiOCl sheets doped with different amount of Er3+ and/or Yb3+ ions were prepared.•The thickness of BiOCl sheets decreased with the increase of Ln ions doping amount.•The doped BiOCl exhibited high degradation efficiency for Rhodamine B dye.•The doped BiOCl retained a good cycling stability.Bismuth oxyhalide (BiOCl) has been demonstrated to be a new and excellent photocatalyst. To further improve its photocatalytic activity, we prepared BiOCl samples doped with different amount of Er3+ and/or Yb3+ ions by a simple hydrothermal method. These doped BiOCl samples exhibit sheet-shaped structure, and their thickness goes down from ~140 nm to ~80 nm with the increase of the Ln doping amount from 0 to 5%. Among these doped samples, BiOCl sheets co-doped with 2.0% Yb3+/0.5% Er3+ (BOC-2.5%) exhibits the highest degradation efficiency of 99.5% for Rhodamine B in 20 min under visible-light illumination, which is 2.8 times the efficiency of undoped BiOCl. Especially, BOC-2.5% still retains the photocatalytic activity of 80% after four cycling test, indicating a good stability. These results confirm that Yb3+/Er3+ co-doped BiOCl is an efficient and stable visible-light-driven photocatalyst.

•Hydrothermal synthesis of Yb3+/Er3+ co-doped Bi2WO6 nanosheets.•High photocatalytic degradation efficiency of 99.5% for Rhodamine B in 20 min.•Good cycling stability.Bi2WO6 has attracted much attention as a visible-light-driven photocatalyst, but its photocatalytic activity should be further improved for future practical application. Herein, we prepared Yb3+/Er3+ co-doped Bi2WO6 (Yb3+/Er3+-Bi2WO6) by a facile hydrothermal route followed by a calcination process. Yb3+/Er3+-Bi2WO6 sample consisted of two dimensional nanosheets with the thickness of about 50 nm and length of 1–2 μm. Under visible light irradiation (λ>400 nm), Yb3+/Er3+-Bi2WO6 exhibited higher photocatalytic degradation efficiency (99.5%) for Rhodamine B than Er3+ doped Bi2WO6 (86.0%) and pure Bi2WO6 (14.7%) in 20 min. Furthermore, after four photodegradation cycles, there was no significant loss for the photocatalytic activity of the nanosheets. Therefore, Yb3+/Er3+-Bi2WO6 nanosheets can be used as an efficient and stable VLD photocatalyst.Download high-res image (330KB)Download full-size image

Semiconductor photocatalysis technology has great potential to become one of the most promising solutions for energy shortages and environmental pollution, and a prerequisite for the photocatalytic application is to obtain efficient, easily recyclable and large-area photocatalysts with nanostructures. In the present work, we have prepared TiO2 nanorod bundles on carbon fibers as flexible and weaveable photocatalyst/photoelectrode. The growth of TiO2 nanorod bundles is realized by using a dip-coating and hydrothermal growth method. TiO2 nanorod-bundles exhibit square-column appearance with size of about 340–400 nm and length of ∼6 μm, and they are in fact composed of small nanorods with diameters of ∼30 nm. Subsequently, 16 bunches of CFs with TiO2 nanorod bundles can be weaved to be a macroscale CFs/TiO2 cloth (weight: 0.2 g, total area: ∼35 cm2) with excellent conductivity and flexibility. With CFs/TiO2 cloth as the working electrode, photoelectrochemical measurements demonstrate that the separation of photo-induced charge carriers can be improved by increasing the applied voltage bias. Furthermore, under the illumination of simulated solar light, CFs/TiO2 cloth can degrade 94.0% Rhodamine B (RhB) in 100 min by photoelectrocatalytic degradation process (bias: 0.6 V vs. SCE), which is higher than the efficiency from single photocatalysis (60.8% RhB) or electrocatalysis (5.6% RhB) process. In addition, CFs/TiO2 cloth can be easily recycled with good performance stability. Therefore, this kind of CFs/TiO2 cloth can be used as a promising, easily recyclable and large-area photocatalyst/photoelectrode in practical application (such as degrading organic pollutants in lake and/or river). More importantly, this work provides some insights into the design of efficient and macroscale photocatalyst/photoelectrode with other nanosized semiconductor for enhancing visible-light-driven photocatalytic activity.

A prerequisite for the selective shielding of solar light is to develop optical materials and coatings, and traditional shielding materials usually combine rare/expensive metal element and also have potential heavy-metal pollution after being abandoned. To solve this problem, herein we develop polypyrrole (PPy) nanoparticles as a novel kind of metal-free ultraviolet (UV)/near-infrared (NIR) shielding material. PPy nanoparticles with diameter of ∼50 nm are synthesized by a simple solution polymerization route, and they exhibit weak absorption in visible region but strong UV/NIR photoabsorption. Subsequently, PPy nanoparticles are mixed with polyacrylic acid (PAA) resin for the preparation of PPy–PAA full-polymer films. PPy–PAA films exhibit good transparency in visible region (400–780 nm) but can efficiently absorb UV (305–400 nm) and NIR (780–2500 nm) light, for example, 0.34 mm-thick film with 0.05 wt% PPy can transmit 63.1% visible light but shield 47.2% UV and 80.9% NIR light. When this PPy–PAA film coated glass is used as the window of the sealed black box, the interior air temperature of the box goes up from room temperature of 25.0 °C to 29.2 or 33.9 °C in 1500 s under the irradiation of strong solar light (0.3 or 0.5 W cm−2). Its temperature elevation (4.2 or 8.9 °C) is remarkably lower compared with that (7.3 or 15.7 °C) from glass slide as window under the other identical condition, resulting from excellent NIR shielding property of PPy. Therefore, PPy nanoparticles have great potential as a novel UV/NIR shielding material for the development of cost-efficient energy-saving full-polymer windows without potential heavy-metal pollution.

WO3−x nanomaterials have been demonstrated to be one kind of efficient near-infrared (NIR) laser-driven photothermal nanoagents, but their photothermal stability is still unsatisfied. In addition, a 980 nm laser is usually used as NIR light source, but it has an overheating effect due to optical absorption of water and biological specimens. To address these problems, we have prepared PEGylated Cs-doped WO3 (CsxWO3) nanorods by a solvothermal synthesis—PEGylation two-step route. CsxWO3 nanorods have diameters of ∼11 nm and lengths of ∼50 nm, and they exhibit increased absorption in the NIR region (700–1100 nm). With PEGylated CsxWO3 nanorods as the photothermal nanoagent, we compare the overheating and penetration effects of 915 and 980 nm lasers as NIR light sources. Compared with the 980 nm laser, the 915 nm laser provides drastically less overheating of water, and higher penetration ability of water/skin due to quite low water absorption. Importantly, under the irradiation of a 915 nm laser, CsxWO3 nanorods exhibit excellent photothermal conversion performance with high stability. Furthermore, by the photothermal effect of PEGylated CsxWO3 nanorods, in vivo cancer cells can be efficiently destroyed under the irradiation of a 915 nm laser. Therefore, PEGylated CsxWO3 nanorods can be used as a promising efficient and stable NIR-laser-driven photothermal agent against in vivo cancer cells.

Copper sulfide (CuS) has emerged as a promising photothermal agent. However, its potential toxic effects still remained poorly understood. Herein, CuS nanoplates were synthesized for toxicity assessment. The in vitro study indicated that the cell viability decreased when CuS nanoplate concentration was higher than 100 μg/mL. CuS nanoplates caused apparent toxicity to HUVEC and RAW 264.7 cells. For acute toxicity, maximum tolerated dose and lethal dose 50 were 8.66 and 54.5 mg/kg, respectively. Furthermore, the sub-chronic toxicity test results indicated that there was no obvious effect at tested doses during the test period. The biodistribution study showed that intravenously administrated CuS nanoplates were mainly present in the spleen, liver and lung. Taken together, our results shed light on the rational design of CuS nanomaterials to minimize toxicity, thus providing a useful guideline in selecting CuS as the photothermal agent for cancer therapy.From the Clinical EditorPhotothermal ablation therapy is a promising new treatment modality for cancer. One of the potential photothermal agents is copper sulfide (CuS). In this article, the potential toxic effects of CuS nanoplates were studied. The authors showed that further modification on the design of CuS nanomaterials was needed to minimize toxicity.Copper sulfide (CuS) nanoplates have recently emerged as a new and promising type of photothermal agent for cancer therapy. However, the potential toxic effects of CuS nanoplates still remained poorly understood. Herein, both in vitro and in vivo extensive studies were performed to evaluate the biocompatibility of CuS nanoplates. It is demonstrated that CuS nanoplates have no obvious toxicity. Therefore, our results provide a useful critical guideline in selecting CuS nanoplates for cancer photothermal ablation therapy.

Near-infrared (NIR) laser-induced photothermal ablation (PTA) therapy has great potential to revolutionize conventional therapeutic approaches for cancers, and a prerequisite is to obtain biocompatible and efficient photothermal agents. Herein, we have developed hydrophilic W18O49 nanowires with average lengths of about 800 nm (abbreviated as W18O49-800 NWs) as an efficient photothermal agent, which are prepared by the solvothermal synthesis—simultaneous PEGylation/exfoliation/breaking two-step route. These W18O49-800 NWs exhibit stronger NIR photoabsorption than short nanowires with average lengths of about 50 nm (abbreviated as W18O49-50 NWs) that are prepared via a solvothermal one-step route. Under irradiation of 980 nm with a safe intensity of 0.72 W cm−2, the aqueous dispersion of W18O49-800 NWs (1.0 mg mL−1) exhibits the temperature elevation by 35.2 °C in 5 min; which is a 37.5% increase compared to that (by 25.6 °C) from W18O49-50 NWs (1.0 mg mL−1). More importantly, under 980 nm laser irradiation (0.72 W cm−2) for 10 min, in vivo cancer cells can be efficiently ablated by the photothermal effects of W18O49-800 NWs. Therefore, these W18O49-800 NWs can be used as a more efficient and promising photothermal nanoagent for the ablation of cancer cells in vivo.

Cu2ZnSnS4 (CZTS) precursor ink routes have been demonstrated to open up new possible ways to fabricate low-cost and high-efficiency CZTS film solar cells, and a prerequisite is to investigate and develop precursor inks. Herein, we report the synthesis of air-stable molecular precursor ink for the construction of CZTS film solar cells. The precursor ink was prepared by dissolving Cu(acac)2, Zn(acac)2, and SnC2O4 and sulfur powder in pyridine, which yielded a viscous black solution. Subsequently, the precursor ink was spin-coated on a Mo-coated glass substrate, and the resulting film was heated in the air to burn off organics, producing an oxide film. The oxide film was subjected to the sulfurization process, in which the effects of sulfurization conditions on composition were investigated. CZTS film was obtained with Cu/(Zn + Sn) = 0.87 and Zn/Sn = 1.09, which is a composition that is close to the previously proposed composition for high-efficiency CZTS film solar cells. This CZTS thin film was used to construct a solar cell, and it exhibited an initial power conversion efficiency of 2.30%. Further improvement of the efficiency can be expected by the optimization of the ink composition, the composition/morphology/thickness/phase of the CZTS layer, and the device structure.

•Facile fabrication of NiO@MnO2 core/shell nanocomposites.•A high specific capacitance of 528.0 F g−1 at the scan rate of 1 mV s−1.•A good cycling stability of 109.9% after 5000 cycles.NiO/MnO2 core/shell nanocomposites have been fabricated by a facile hydrothermal method. The nanocomposites consist of NiO nanowires with the diameter of 70–80 nm which are coated by plenty of MnO2 nanosheets as secondary nanostructures. The NiO@MnO2 nanocomposites are used subsequently to construct a pseudocapacitor. Electrochemical tests reveal a high specific capacitance of 528.0 F g−1 at a scan rate of 1 mV s−1 and a good cycling stability of 109.9% after 5000 cycles, both of which are much higher compared to that of the pseudocapacitor based on pure NiO nanowires (307.0 F g−1 and 87.8%, respectively). Therefore, these NiO/MnO2 nanocomposites have great superiority as electrode material in high-performance pseudocapacitors.

Wireless nanobiodevices (such as nanorobots) have great potential to revolutionize the diagnosis and therapeutic system for human health, but their applications have been limited by difficulties in fabricating such nanobiodevices, and one of the difficulties is to obtain an in vivo energy source as their biopower component. To address this problem, we have developed a kind of 980 nm laser-driven photovoltaic cell (980LD-PVC) by introducing a NaYF4:Yb,Er nanophosphor layer in conventional dye-sensitized solar cells, and its performance has been optimized by improving the up-conversion luminescence intensity of NaYF4:Yb,Er nanophosphors and adopting a succinonitrile-based gel electrolyte. Under the direct irradiation of a 980 nm laser with an illumination area of 2 × 8 mm2 and a safe intensity of 720 mW cm−2 that is slightly lower than the conservative limit (726 mW cm−2) for human skin exposure, 980LD-PVC without a liquid component exhibits a maximum output power of 44.5 μW and an overall 980 nm laser-to-electrical energy conversion efficiency of 0.039%. In particular, after being covered with chicken skin (thickness: 1 mm) as a model of biological tissue, 980LD-PVC still possesses a maximum output power of 22.2 μW and an overall conversion efficiency of 0.019%, which is still excellent enough to satisfy the power requirements of in vivo nanorobots (at least 1 μW) and cardiac pacemakers (about 10 μW). This research paves the way for the development of novel electrical sources to power wireless nanobiodevices and many other biodevices implanted under the human skin.

The in situ preparation of semiconductor films on a flexible metal foil has attracted increasing attention for constructing flexible solar cells. In this work, we have developed an in situgrowth strategy for preparing CuInS2 (CIS) films by solvothermally treating flexible Cu foil in an ethylene glycol solution containing InCl3·4H2O and thioacetamide with a concentration ratio of 1:2. The effects of solvothermal temperature, time and concentration on the morphology and phase of the CIS films are investigated. Solvothermal temperature has no obvious effect on the morphology of the final films, but higher temperature is favorable for the growth of CIS films with higher crystallinity. Reactant concentration plays a significant role in controlling the morphology of CIS films; if InCl3·4H2O concentration is relatively low (≤0.042 M), single-layered CIS films can be produced, which are composed of high ordered potato chips shaped nanosheets, otherwise, it prefers to form a double-layered film, for which the lower layer is similar CIS ordered nanosheets while the upper layer is composed of flower shaped superstructures. A possible mechanism of the CIS films is also investigated. UV-vis measurements show that all these CIS films possess a direct bandgap energy of 1.48 eV, appropriate for the absorption of the solar spectrum. Finally, single-layered CIS films on Cu foil were employed for fabricating flexible solar cells with a structure of Cu foil/CuInS2/CdS/i–ZnO/ITO/Ni–Al, and the resulting cells yield a power conversion efficiency of 0.75%. Further improvement of the efficiencies of the solar cells can be expected by optimizing the morphology, structure and composition of the CIS films, as well as the fabrication technique.

Using Cu2ZnSnS4 (CZTS) nanocrystal-based ink (via a solvothermal route) and roll-to-roll printing, CZTS films are prepared on a Mo-coated Al foil, and then flexible solar cells with a structure of Al foil/Mo/CZTS/ZnS/i-ZnO/ITO/Al–Ni and a power conversion efficiency of 1.94% are constructed, in which all the materials are low-cost and environmentally friendly.

Rare earth nanoparticles (RENPs) have great superiority as luminescent materials for broad applications, and a prerequisite for most of their application is to obtain hydrophilic RENPs with efficient luminescence and small diameter (<10 nm). To address this problem, we report a facile one-pot sonochemical route with tetraethylene glycol as the solvent and tetrafluoroborate-based ionic liquid as the fluorine source for the synthesis of LaF3:Ce,Tb as the model of RENPs. LaF3:Ce,Tb nanoparticles with the diameter of about 6 nm were prepared in a very short ultrasound time (10 min). Fourier transform infrared spectrum reveals the presence of tetraethylene glycol ligands on their surface, which confers high solubility of LaF3:Ce,Tb nanoparticles in water. Under 254 nm UV excitation, the aqueous dispersion of LaF3:Ce,Tb nanoparticles exhibits strong green emission with luminescent quantum yield of ∼50%. This work probably contributes to not only the fundamental research of shape-controlled LaF3:Ce,Tb nanoparticles but also new methods of producing other RENPs for broad applications.

Fiber-shaped solar cells (FSCs) have attracted increasing interest in recent years due to their numerous advantages. Herein we report the first prototype of highly flexible all-solid-state single-wire FSCs by using CuInSe2 (CIS) as the model photoactive semiconductor. CIS layer is electrodeposited on a flexible Mo wire as the substrate. Subsequently, CdS, ZnO and ITO layers are orderly deposited on the Mo/CIS wire, and each upper layer ensures full contact with the underlying layer, resulting in an excellent structural uniformity along circumference of the FSC. This Mo/CIS/CdS/ZnO/ITO single-wire FSC exhibits a power conversion efficiency of 2.31%, which is one of the highest values in all reported FSCs. More importantly, the present all-solid-state single-wire FSC exhibits stable conversion efficiency (2.16–2.32%) during rotation (0∼360°), bending (0∼360°) and long-time aging (stored at 60 °C for 600 h) processes, which makes it possible to fabricate very long single-wire FSC with stable efficiency for weaving large-area devices and/or the stereoscopic cell textiles. Our method provides a new and general approach for fabricating flexible single-wire FSC with various kinds of photovoltaic semiconductor materials, and it also would be applicable to develop other flexible electronic circuits.Graphical AbstractSingle-wire-shaped flexible solar cell based on Mo/CIS/CdS/ZnO/ITO has been constructed and it exhibits a power conversion efficiency of 2.31%. Importantly, it has an excellent structural uniformity and stable conversion efficiency during rotation, bending and long-time aging process, which demonstrates the great potential application in fabricating very long single-wire solar cell for weaving large-area stereoscopic cell textiles.Highlights► We construct fiber-shaped solar cells with Mo/CuInSe2/CdS/ZnO/ITO single-wire-structure. ► This fiber-shaped solar cell has a photoelectric conversion efficiency of 2.31%. ► Its conversion efficiency remains stable during rotation, bending and long-time aging processes. ► This approach opens a reliable path for weaving the stereoscopic cell textiles.

Rare-earth up-converting nano-phosphors (RUNPs) have wide applications, and most of these applications require hydrophilic RUNPs with high up-converting luminescence efficiency. In this work, we report a simultaneous control of the phase and luminescent intensity of hydrophilic Gd3+ doped NaYF4:Yb/Er nanoparticles with diameters of 40–100 nm, which were prepared by a facile one-pot solvothermal synthesis with ethylene glycol as the solvent and poly(vinylpyrrolidone) as the ligands at 220 °C for different time. When reaction time is 3 h, the increase of Gd3+ dopant concentration from 0 to 30 mol% results in the transformation from cubic to hexagonal phase, and pure hexagonal phase NaYF4:Yb/Er nanoparticles can be obtained with Gd3+ dopant concentration up to 30 mol%. Gd3+ dopant concentration at 15 mol% leads to a maximal luminescent intensity in a wide dopant range of 0–80 mol%. Furthermore, the increase of reaction time from 3 to 24 h favors the formation of hexagonal phase samples and therefore improves greatly luminescence intensity. 15 mol% Gd3+ doped NaYF4:Yb/Er nanoparticles prepared for 24 h exhibit the highest upconverting luminescence intensity which is almost 11 times as strong as that of ones prepared for 3 h and almost 28 times as strong as that of hexagonal phase NaGdF4:Yb/Er (namely NaYF4:Yb/Er sample with 80 mol% Gd3+ prepared for 3 h). Due to its small size, high hydrophilicity and excellent up-converting luminescence, this 15 mol% doped NaYF4:Yb/Er sample has great superiority for biological applications.Graphical abstractHighlights► Hydrophilic Gd3+ doped NaYF4:Yb,Er nanoparticles have been prepared by a facile one-pot solvothermal synthesis. ► The control of their phase and upconverting luminescent intensity can be realized by tuning Gd3+ dopant concentration and solvothermal time. ► Due to its small size, high hydrophilicity and excellent up-converting luminescence, the 15 mol% doped NaYF4:Yb/Er sample has great superiority for biological applications.

In this work, we report a facile solvothermal synthesis of NaYF4:Yb/Er nano-structured materials with controlled shapes by tuning the solvents. Ethylene glycol as the solvent results in the preparation of NaYF4:Yb/Er nanoparticles with diameter of about 10 nm, while polyethylene glycol (MW = 400, abbreviated as PEG-400) as the solvent facilitates the formation of NaYF4 superstructures with the particle size of about 160 nm. These NaYF4 superstructures are built from nanoparticles with diameter of about 10 nm. Their compositions have been confirmed by energy-dispersive X-ray analysis, and they have simultaneously cubic and hexagonal phase structures. Fourier transform infrared (FT-IR) spectrum reveals the presence of PEG-400 ligands on their surface, which confers high solubility of NaYF4 superstructures in water. Under continuous-wave excitation of 980 nm laser, NaYF4 superstructure aqueous solution exhibits efficient up-converting luminescence which is almost twice as strong as that of the building blocks (nanoparticles). This improvement may result from the fact that these NaYF4:Yb,Er superstructures can serve as 980 nm laser-cavity mirrors. Therefore, these superstructures have great superiority as luminescent labeling materials for biological applications.

We have reported a non-injection one-pot synthesis of the alloyed ZnxCd1−xS semiconductor nanocrystals (SNCs) with controlled shapes and compositions. This non-injection approach involves heating two molecular precursors (cadmium ethylxanthate and zinc ethylxanthate) as metal and S sources in organic solvents at 320 °C for 30 min, which results in the thermal decompositions of the molecular precursors to produce ZnxCd1−xS. The effects of solvents and compositions on the shapes and structures of ZnxCd1−xS SNCs have been investigated. The mixture solvent containing oleic acid, paraffin oil and oleylamine (such as a volume ratio: 1/2/1) results in the preparation of uniform ZnxCd1−xS nanoparticles with diameters of 7–13 nm, while pure oleylamine or the mixture of oleylamine and paraffin oil as the solvent leads to the formation of uniform ZnxCd1−xS nanorods. Monodisperse wurtzite ZnxCd1−xS nanorods with different compositions have been prepared in pure oleylamine, and no obvious effects of the compositions on their shapes are found. Their alloying nature is consistently confirmed by the results of high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD) and optical measurements. These alloyed ZnxCd1−xS nanorods exhibit composition-dependent absorption and emission properties, and therefore they can be promising candidates as emitting materials.

Wireless nanobiodevices (such as nanorobots) have great potential to revolutionize the diagnosis and therapeutic system for human health, but their applications have been limited by difficulties in fabricating such nanobiodevices, and one of the difficulties is to obtain an in vivo energy source as their biopower component. To address this problem, we have developed a kind of 980 nm laser-driven photovoltaic cell (980LD-PVC) by introducing a NaYF4:Yb,Er nanophosphor layer in conventional dye-sensitized solar cells, and its performance has been optimized by improving the up-conversion luminescence intensity of NaYF4:Yb,Er nanophosphors and adopting a succinonitrile-based gel electrolyte. Under the direct irradiation of a 980 nm laser with an illumination area of 2 × 8 mm2 and a safe intensity of 720 mW cm−2 that is slightly lower than the conservative limit (726 mW cm−2) for human skin exposure, 980LD-PVC without a liquid component exhibits a maximum output power of 44.5 μW and an overall 980 nm laser-to-electrical energy conversion efficiency of 0.039%. In particular, after being covered with chicken skin (thickness: 1 mm) as a model of biological tissue, 980LD-PVC still possesses a maximum output power of 22.2 μW and an overall conversion efficiency of 0.019%, which is still excellent enough to satisfy the power requirements of in vivo nanorobots (at least 1 μW) and cardiac pacemakers (about 10 μW). This research paves the way for the development of novel electrical sources to power wireless nanobiodevices and many other biodevices implanted under the human skin.

Near-infrared (NIR) laser-induced photothermal ablation (PTA) therapy has great potential to revolutionize conventional therapeutic approaches for cancers, and a prerequisite is to obtain biocompatible and efficient photothermal agents. Herein, we have developed hydrophilic W18O49 nanowires with average lengths of about 800 nm (abbreviated as W18O49-800 NWs) as an efficient photothermal agent, which are prepared by the solvothermal synthesis—simultaneous PEGylation/exfoliation/breaking two-step route. These W18O49-800 NWs exhibit stronger NIR photoabsorption than short nanowires with average lengths of about 50 nm (abbreviated as W18O49-50 NWs) that are prepared via a solvothermal one-step route. Under irradiation of 980 nm with a safe intensity of 0.72 W cm−2, the aqueous dispersion of W18O49-800 NWs (1.0 mg mL−1) exhibits the temperature elevation by 35.2 °C in 5 min; which is a 37.5% increase compared to that (by 25.6 °C) from W18O49-50 NWs (1.0 mg mL−1). More importantly, under 980 nm laser irradiation (0.72 W cm−2) for 10 min, in vivo cancer cells can be efficiently ablated by the photothermal effects of W18O49-800 NWs. Therefore, these W18O49-800 NWs can be used as a more efficient and promising photothermal nanoagent for the ablation of cancer cells in vivo.