Despite one-dimensional (1D) semiconductor nanostructure arrays attracting increasing attention due to their many advantages, highly ordered TiO2 nanorod arrays (TiO2 NR) are rarely grown in situ on Ti substrates. Herein, a feasible method to fabricate TiO2 NRs on Ti substrates by using a through-mask anodization process is reported. Self-ordered anodic aluminum oxide (AAO) overlaid on Ti substrate was used as a nanotemplate to induce the growth of TiO2 NRs. The NR length and diameter could be controlled by adjusting anodization parameters such as electrochemical anodization voltage, anodization time and temperature, and electrolyte composition. Furthermore, according to the proposed NR formation mechanism, the anodized Ti ions migrate and deposit in the AAO nanochannels to form Ti(OH)4 or amorphous TiO2 NRs under electric field, owing to the confinement effect of the template. Photoelectrochemical tests indicated that, after hydrogenation, the TiO2 NRs presented higher photocurrent density under simulated sunlight and visible light illuminations, suggesting their potential use in photoelectrochemical water splitting, photocatalysis, solar cells, and sensors.

Hollow mesoporous silica nanospheres were prepared using different types of templates such as iron oxide nanoparticles (magnetite and hematite) and polymer nanospheres (polystyrene and resorcinol formaldehyde resin). The process involves a first step of coating silica on templates along with surfactants and then removal of both templates and surfactants to produce hollow mesoporous silica nanospheres in the second step. TEM, XRD, FTIR, TGA, and N2-adsorption–desorption analysis were used to characterize the samples and indicated the hollow and mesoporous structure of silica nanospheres. Ibuprofen as a drug model was used to investigate the drug adsorption behavior of the silica nanospheres which also showed sustained release properties.

Hematite (α-Fe2O3) is a red material with a band gap of about 2.0 eV, which indicates that it can absorb more solar light. It is a promising photocatalyst applied in many fields. In this paper, α-Fe2O3 single crystal hollow hexagonal bipyramids were synthesized by a simple one-pot hydrothermal method. The morphology and structure of the prepared α-Fe2O3 hollow hexagonal bipyramids were studied using scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD). The hollow single crystals show a good light absorption and performance in photodegradation of methylene blue (MB). Due to the strategy of depositing ultra-thin layers of Al2O3 by atomic layer deposition (ALD), the photoelectrochemical (PEC) performance of α-Fe2O3 under the simulated solar light irradiation is also improved.

•The output of PVDF and Nylon based TENG was highly enhanced by adding an PI transition layer.•The thickness, morphology, polarity and charge decay property of transition layer play important roles in TENG's output.•The TENG with PI transition layer achieves a peak Vo of 1010 V and Isc of 65 μA.A new structured triboelectric nanogenerators (TENG) was designed by adding a transition layer between the friction layer and the conduct layer, which could significantly improve the output performance by one order of magnitude. The material of transition layer, such as polyimide, has high ability to store the triboelectrification charges, resulting in more induced charges and higher external current. After adding a polyimide charge storage layer with the thickness of 25 µm, the short-circuit current and output voltage of polyvinylidene fluoride (PVDF) and nylon (NY) based TENG (Cu-PI-PVDF@NY-Cu) increased from 9.2 μA to 65 μA, and 110 V to 1010 V, respectively. The maximum charge density can reach approximately 105 μC/m2 with the maximum value of the output power of 5.87 mW under 4 MΩ loading resistance, which can instantaneous light up 992 commercial LEDs and charge a capacitor with the speed increased by 10 times. Moreover, the mechanism and influence factors including the surface structure, composition and thickness of the charge keeping layer to enhance the output of TENGs were discussed in detail. The charge decay tests of the transition layers showed that polyimide layer has very good charge keeping ability with a decay rate of only about 20% in 4 h, while the charge of PVDF decrease about 97% in 4 h, which is a key factor for its lower output.A new protocol toward high output triboelectric nanogenerator was introduced by adding a transition layer as the charge storage layer. Due to the charge retention property, the TENG with PI charge storage layer obtains a high short-circuit current and output voltage values of 65 μA and 1010 V, respectively. This study gives some guidance for choosing materials as charge storage layer to improve the output of TENGs, which paves a route to drive the practical applications of TENGs in energy harvesting, self-powered sensors, and so on.Download high-res image (194KB)Download full-size image

•A new smart U-shaped TENG based on liquid-solid contact electrification is proposed.•The complicated mechanical motions can be transmitted into liquid pressure and electricity signal by U-shaped TENG.•The U-shaped TENG can be working as smart multifunctional sensors to detect the displacement, pressure, torsion, and so on.A new smart U-shaped triboelectric nanogenerator (TENG) was reported basing on solid-liquid contact triboelectrification and the Pascal's law, in which the complicated mechanical motions can be transmitted into liquid pressure and electricity signal. The U-shaped TENG driven by inertial force and air flow is designed as an energy harvesting device to collect the mechanical energy with a stable peak output voltage and current of about 20 V and 400 nA, respectively. The relationship between the output performance and the water sliding conditions is investigated in detail with a stable peak output performance at the point of resonance. The U-shaped TENG can also be working as smart multifunctional sensors to detect the displacement, pressure, torsion, and so on. As a self-powered displacement sensor, the U-shaped TENG shows a high sensitivity of 0.91 V mm−1 and 8.50 nA mm−1. As a pressure sensor, it also exhibits a high sensitivity of 4.41 V kPa−1 and 72.94 nA kPa−1, respectively. This work expands the practical applications of the solid-liquid triboelectrification based TENGs for energy harvesting and smart sensors in wide fields with advantages of simple fabrication, low cost, portable and self-powered properties.A U-shaped triboelectric nanogenerator (TENG) is presented for energy harvesting and self-powered sensors. The design of the TENG incorporates the solid-liquid contact triboelectrification and the pascal's law. This device can transmit undiminished the complicated mechanical motions into liquid pressure to avoid direct contact of the external mechanical motion with the U-shaped TENG. The newly designed TENG is promising for smart multifunctional sensors to detect the displacement, pressure, torsion, and so on.Download high-res image (123KB)Download full-size image

•TiO2 nanotube was hydrogenated at 550 °C for 30 min in H2 atmosphere.•Hydrogenated TiO2 nanotube arrays express enhanced PEC performance under visible light.•The hydrogenated TiO2 nanotube was used for photocathodic protection under solar light.The hydrogenated TiO2 nanotube arrays (H-TiO2 NTs) were prepared by annealing anodized TiO2 NTs in hydrogen atmosphere, and then used as photoanodes for photocathodic protection of 304 stainless steel (304SS) under visible light and simulated solar light. The effects of hydrogenated temperature and time on the photoeletrochemical (PEC) performance of H-TiO2 NTs were studied in details. The PEC tests showed that the photocurrent density of H-TiO2 NTs was up to 270.8 μA/cm2 and 1.20 mA/cm2 under visible and simulated solar light with good stability, which is about 23 times and 4.5 times than that of pristine TiO2 NTs. Furthermore, photo-induced open circuit potential (OCP) and Tafel curves were measured to evaluate the photocathodic protection effect of H-TiO2 NTs. Salient visible light responses and sharp decline of the OCP made H-TiO2 NTs a promising photocathodic protection material and could be applied to protect the coupled 304 stainless steel from corrosion.The photocurrent density of hydrogenated TiO2 nanotube arrays (H-TiO2 NTs) have significant enhancement, which is about 23 times than that of pristine TiO2 NTs, owing to enlarged visible light response and the oxygen vacancies produced in the hydrogenation.

•We fabricated PP nanowire based TENG.•The output performance was adjusted by structural control and surface functionalization.•After modified by PFTS, the device achieved a peak Voc of 1900 V and Jsc of 19 mA/m2.•The PFTS modified TENG can light up 372 commercial LEDs.•The PFTS modified TENG can power a simple temperature sensor.We report a new method to fabricate a polypropylene (PP) nanowire array based triboelectric nanogenerator (TENG) with high output through structural control and surface functionalization for harvesting friction mechanical energy. Compared with the smooth PP film based TENG, the short circuit current (Isc) and open circuit voltage (Voc) of the PP nanowire based TENGs with the nanowire diameter of about 100 nm and length of about 14 μm increase by more than 4 times. More importantly, after surface functionalization with a modifier of 1H,1H,2H,2H-perfluorooctyltrichlorosilane, the output of the PP nanowire based TENG is further increased to a maximum Voc of 1900 V and a short circuit current density of 19 mA/m2, increased by more than 100 times than that of the flat PP film based TENG. This TENG can light up 372 commercial LEDs. Furthermore, a self-powered temperature sensor is designed, which shows great potential application in daily life. By taking this simple and effective surface modification strategy, we believe various materials could be used for energy harvesting by TENGs and other devices with high performance.PP nanowire based TENGs with high output were fabricated by structural control and surface functionalization. The PP nanowire based TENG achieved a peak voltage of 1900 V and current density of 19 mA/m2 after modification with PFTS, which can light up 372 commercial LEDs and power a simple temperature sensor from room temperature to 100 oC.

A simple method to improve the photoelectrochemical performance of TiO2 nanotube arrays (NTs) by simple air plasma post-treatment is reported. The air plasma treated sample shows higher photocurrent density and incident photo current efficiency with high stability, about 3–4 times that of the pristine TiO2 NTs even after six months.

•Aligned TiO2 NTs with Mo-doping and mixed phase are achieved by one step hydrothermal process.•Oxygen vacancies are increased and recombination of photo-excited charge is reduced.•The photocurrent density is doubled.•Mo-doped TiO2 NTs show visible-light absorption and high stability.Molybdenum-doped TiO2 nanotube arrays (Mo-doped TiO2 NTs) photoelectrodes with anatase/rutile mixed phase are successfully fabricated via two-step anodization of titanium followed by a hydrothermal doping treatment process. The Mo-doped TiO2 NT material shows higher photocurrent density and enhanced incident photon to current conversion efficiency (IPCE) compared with the pristine TiO2 NTs for photoelectrochemical (PEC) water-splitting. The improvement of PEC response results from not only the increasing of oxygen vacancies and reducing of the recombination of photoexcited charges by Mo-doping, but also the new formed heterojunctions of anatase/rutile mixed-phase by hydrothermal treatment. Moreover, the Mo-doped TiO2 NTs show high stability and obvious visible absorption with considerable photocurrent density under visible light (λ > 420 nm).

•A PPy NW/TiO2 NT coaxial heterojunction nanocomposite was prepared.•The nanocomposite showed obvious visible light responses.•The ordered structure enhanced the photocurrent density of the resultant nanocomposite.•Photogenerated cathodic protection for 304 stainless steel was observed.A new photoanode polypyrrole nanowire/TiO2 nanotube (PPy NW/TiO2 NT) nanocomposite material with a coaxial heterojunction structure is constructed by electrodeposting p-type polypyrrole nanowire into n-type TiO2 nanotubes. Photo-induced open circuit potential, photocurrent density, electrochemical impedance spectroscopy, and Tafel curves are measured under visible light to evaluate the photocathodic protection effect and anticorrosion properties of the nanocomposite. The results indicate that the synergistic effect between the photogenerated cathodic protection and the favorable corrosion resistance of the nanocomposite makes PPy NW/TiO2 NTs nanocomposite a promising material for protecting Ti substrate and the coupled 304 stainless steel from corrosion.

In this paper magnetic nanocomposite catalysts, with a single gold catalytic layer (Fe3O4@SiO2-Au and Fe3O4@SiO2-Au@mSiO2), double gold catalytic layers (Fe3O4@SiO2-Au@mSiO2-Au), and with one gold layer and one silver layer (Fe3O4@SiO2-Au@mSiO2-Ag), were prepared through simple steps. Different techniques were used for characterization of the as prepared nanocomposite catalysts, such as transmission electron microscopy (TEM), X-ray diffraction (XRD), a vibrating sample magnetometer (VSM), energy-dispersive X-ray spectroscopy (EDX) etc. The catalysts were used for the catalytic reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) in the presence of NaHB4. All the nanocomposite catalysts showed very good catalytic activity; however the nanocomposites with double catalytic layers (Fe3O4@SiO2-Au@mSiO2-Au and Fe3O4@SiO2-Au@mSiO2-Ag) showed excellent catalytic activity for the reduction reaction of 4-nitrophenol. Due to the magnetic core, the nanocomposite catalysts showed magnetic properties and can be easily separated and recycled many times without any loss in activity. In the case of nanocomposite catalysts with Au nanoparticles protected by silica (Fe3O4@SiO2-Au@mSiO2) indicated better recyclability compared to other nanocomposites.

This paper presents a facile method for preparing Ag nanoparticle (NP)-loaded superamphiphobic surfaces on an Al substrate with efficient anticorrosion and antibacterial properties. A hierarchical steplike microstructure with nanopores is fabricated on an Al surface through facile chemical etching and anodization; subsequent fluorination confers superhydrophobic and superoleophobic properties to this surface. Ag NPs are loaded on the surface nanopores and stabilized by a self-assembled aminopropyltriethoxysilane monolayer through amino-group bonding to prevent aggregation and loss of Ag NPs. Compared with Ag NP-loaded pristine Al substrates, the Ag NP-coated superamphiphobic surface can effectively prevent corrosion of the Al substrate and bacterial absorption, as confirmed by electrochemical impedance spectroscopy, Tafel plot measurement, and bactericidal tests. This study provides novel insights into functional superamphiphobic materials with anticorrosion and antibacterial properties.

The asymmetrical distribution of specific proteins on both sides the cell membrane, which is used to adjust the ion permeability, is magical inside the body of a living creature. These porous membrane materials with asymmetric micro/nanochannels are very common and important in both nature and artificial materials. Inspired by this, the construction of intelligent nanodevices with multifunctional properties is urgent and significant. Here a general strategy based on simultaneous chemical polymerization reactions in both sides of an anodic aluminum oxide (AAO) membrane is reported, combining with atom transfer radical polymerization (ATRP), dopamine self-polymerization (DOP-SP) and ring-opening metathesis polymerization (ROMP) technologies, to form various asymmetric membranes in the AAO nanochannels. By this method, double hydrophilic poly(3-sulfopropyl methacrylate potassium salt)@poly(2-(methacryloyloxy)ethyl-methylammonium chloride) (PSPMA@PMETAC), temperature and pH double responsive poly(N-isopropylacrylamide)@poly(dimethylamino)ethyl methacrylate (PNIPAM@PDMAEMA), and hydrophilic/hydrophobic poly(3-sulfopropyl methacrylate potassium salt)@poly(hydrophobic pentadecafluorooctyl-5-norbornene-2-carboxylate) (PSPMA@PNCA-F15) polymer brushes-modified asymmetrical AAO nanochannel array membranes were successfully prepared. Moreover, after the in situ ion exchange and reduction reaction of the double hydrophilic PSPMA@PMETAC membrane, we prepared polymer brushes-stabilized Au–Pd asymmetrically-modified AAO nanochannels, showing excellent flow-through catalysis.

A straightforward method is presented for the synthesis of onion like carbon nanoparticles from candle soot (CS) that can be used as an effective electrode material for supercapacitors. Based on well shaped candle soot, a pompom like core–shell MnO2@CS nanocomposite material was also developed to increase the specific capacitance as high as 309 F g−1.

•Polymers grafting from TiO2 nanotubes surface is synthesized.•The composite improves the TiO2 NTs storage capacity.•The composite allows Ag ions release in a controlled manner.•The in vitro experiments show the composite has a good cell proliferation.Bacterial infection has been identified as one of the major causes of titanium implant failures. In this study, a novel antibiotic vehicle composite, TiO2NT–PSPMA, was synthesized via atom transfer radical polymerization; this method improved the local antibiotic concentration and prolonged its sustainable release by loading larger amounts of antibiotic into titania nanotubes (TiO2 NTs) arrayed on Ti implants. Ag nanoparticles (NPs) were loaded into TiO2 NTs with the assistance of the ionic polymer 3-sulfopropyl methacrylate potassium salt (PSPMA). This composite increased the storage of Ag NPs by employing nanotubes and using PSPMA to trap larger amounts Ag NPs. The in vitro experiments showed that the composite had a dose-dependent cell proliferation by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), indicating that the composite has the potential to prevent the devastating consequences of implant infection.

Smart systems on the nanometer scale for continuous flow-through reaction present fascinating advantages in heterogeneous catalysis, in which a parallel array of straight nanochannels offers a platform with high surface area for assembling and stabilizing metallic nanoparticles working as catalysts. Herein we demonstrate a method for finely modifying the nanoporous anodic aluminum oxide (AAO), and further integration of nanoreactors. By using atomic transfer radical polymerization (ATRP), polymer brushes were successfully grafted on the inner wall of the nanochannels of the AAO membrane, followed by exchanging counter ions with a precursor for nanoparticles (NPs), and used as the template for deposition of well-defined Au NPs. The membrane was used as a functional nanochannel for novel flow-through catalysis. High catalytic performance and instantaneous separation of products from the reaction system was achieved in reduction of 4-nitrophenol.

The asymmetrical distribution of specific proteins on both sides the cell membrane, which is used to adjust the ion permeability, is magical inside the body of a living creature. These porous membrane materials with asymmetric micro/nanochannels are very common and important in both nature and artificial materials. Inspired by this, the construction of intelligent nanodevices with multifunctional properties is urgent and significant. Here a general strategy based on simultaneous chemical polymerization reactions in both sides of an anodic aluminum oxide (AAO) membrane is reported, combining with atom transfer radical polymerization (ATRP), dopamine self-polymerization (DOP-SP) and ring-opening metathesis polymerization (ROMP) technologies, to form various asymmetric membranes in the AAO nanochannels. By this method, double hydrophilic poly(3-sulfopropyl methacrylate potassium salt)@poly(2-(methacryloyloxy)ethyl-methylammonium chloride) (PSPMA@PMETAC), temperature and pH double responsive poly(N-isopropylacrylamide)@poly(dimethylamino)ethyl methacrylate (PNIPAM@PDMAEMA), and hydrophilic/hydrophobic poly(3-sulfopropyl methacrylate potassium salt)@poly(hydrophobic pentadecafluorooctyl-5-norbornene-2-carboxylate) (PSPMA@PNCA-F15) polymer brushes-modified asymmetrical AAO nanochannel array membranes were successfully prepared. Moreover, after the in situ ion exchange and reduction reaction of the double hydrophilic PSPMA@PMETAC membrane, we prepared polymer brushes-stabilized Au–Pd asymmetrically-modified AAO nanochannels, showing excellent flow-through catalysis.

A simple method to improve the photoelectrochemical performance of TiO2 nanotube arrays (NTs) by simple air plasma post-treatment is reported. The air plasma treated sample shows higher photocurrent density and incident photo current efficiency with high stability, about 3–4 times that of the pristine TiO2 NTs even after six months.

As a new type of energy harvesting device, the triboelectric nanogenerator (TENG) can convert almost all kinds of mechanical energy into electricity based on the coupling of triboelectrification and electrostatic induction. Here, a novel TENG is constructed with a conducting polymer polypyrrole nanowire (PPy NW) electrode, which is prepared by an electrochemical polymerization method with anodic aluminum oxide (AAO) as the template. The PPy NW-based TENG shows high output performance with a maximum short circuit current density of 23.4 mA m−2 and output voltage of 351 V, which can light 372 commercial red LEDs. Moreover, a self-powered anticorrosion system powered by the PPy NW-based TENG is designed, which can provide extra electrons to inject into the surface of the protected metals, forming effective impressed current cathodic protection by harvesting mechanical energy or wind energy. This smart device has potential applications for protecting metals from corrosion in daily life, industrial production and ocean exploration by harvesting the energies in the ambient environment.