A simple hydrothermal process involving thermal diffusion has been developed to synthesize almost vertical doped titanium dioxide (TiO2) nanorod arrays on a silicon (Si) surface. The enhanced ultraviolet-visible (UV-vis) light photodetectors with a TiO2/Si heterojunction were fabricated using band engineering, by doping indium (In) or nitrogen (N) in TiO2 nanorod arrays. The photodiodes showed high quantum efficiencies of 200–400% under visible light illumination (e.g., 565 nm), and ∼16% with UV light (365 nm). Additionally, the N-doped TiO2/Si devices, with a unilateral linearly graded junction, had greater rectification characteristics, lower dark current, better quantum efficiency and response to UV detection, and the In-doped TiO2/Si heterojunction had a better multiplication factor for weak visible light detection, with a decreased electronic barrier and increased carrier concentration. These excellent results mean that doped TiO2/Si heterojunctions will be useful for new UV-vis light detection enhanced photodiodes which do not require expensive auxiliary equipment, thus making them easy to use in applications involving portable and wearable equipment.

A self-powered high-performance broadband photodetector was fabricated, based on n-Si(111)/p-NiO heterojunctions consisting of single-crystal NiO nanosheets, via a facile hydrothermal method. The device exhibited broadband detection capabilities (350–600 nm) and excellent self-powered performance, with an external quantum efficiency (EQE) as high as ∼20% under zero bias. Under a low reverse bias of −0.2 V, the highest photosensitivity (photo-dark current ratio) values of 938% and 2249% were achieved under illumination from 350 nm and 600 nm light (0.5 mW cm−2), respectively, which was several orders of magnitude higher than for previously reported Si/NiO heterojunction photodetectors. Under a high reverse bias of −2 V, the excellent EQE of the device was found to be between 62.5% and 89.5% upon illumination from 350–600 nm light. In addition, the fast response speed of the as-fabricated device was less than 30 ms. The results indicate that n-Si(111)/p-NiO heterojunction photodetectors made of single-crystal NiO nanosheets have obvious advantages for application in high-performance and energy-saving optoelectronic devices.

•The MoO3/MnO2 core-shell materials were prepared by a facile two-step process.•The morphology and corresponding properties of the MoO3/MnO2 were studied.•The MoO3/MnO2 exhibit high specific capacitance and good rate capability.Hierarchical MoO3/MnO2 core-shell nanostructures were prepared by a hydrothermal process followed by in-situ oxidative polymerization as an integrated electrode material for supercapacitors. The core-shell MoO3/MnO2 nanocomposites exhibited excellent electrochemical properties with high specific capacitance of 352.4 F g−1 at 1 A g−1 and desirable rate capability in 1 M NaOH solution. The superior electrochemical performances could be ascribed to the MoO3/MnO2 core-shell nanostructures which make two types of pseudocapacitive materials connected physically and significantly improve electrolyte diffusion efficiency and electron transport. These MoO3/MnO2 core-shell nanostructures with remarkable electrochemical performances could be considered as a prospective candidate for the application of supercapacitors.

Herein, a simple and an environmentally friendly approach is developed to fabricate the novel MnO@C hierarchical structure, derived from Mn-based metal organic frameworks, which is explored as an anode material for lithium ion batteries. Remarkably, the MnO@C microsphere electrode delivers an outstanding, long cycling capacity of 596.3 mA h g−1 at 5C (1C = 765 mA g−1) after 1000 cycles, and an excellent rate performance of 380.1 mA h g−1 at 10C. The overall outstanding properties of the hierarchical MnO@C composite can be attributed to the success of a new strategy for dual structure design, which provides two pathways for effectively alleviating volume changes and enhancing conductivity based on in situ TEM electrochemical experiments and electrochemical impedance spectra. Both the poor conductivity and great volume changes of the MnO electrode material can be effectively improved in two ways: the porous carbon matrix confining the MnO nanoparticles, and the hierarchical nanorod-assembled architecture. The structures herein suggest new design concepts for metal oxide nanoarchitectures for high performance electrode materials in lithium ion batteries.

Herein, we report a photocatalytic heterojunction device of rutile TiO2 nanorod arrays based on a p–n silicon junction (TiO2@PN) and its full absorption of ultraviolet and visible light for synergistic photodegradation. The fabricated TiO2@PN had excellent photocatalytic degradation of methyl orange (MO) under irradiation of a 300 W Xe lamp, and its pseudo-first-order rate constant k was 0.221 h−1, which was greatly higher than that for TiO2 nanorod arrays based on an n–p silicon junction (TiO2@NP, 0.078 h−1) and glass (TiO2@G, 0.032 h−1). The higher photocatalytic performance of TiO2@PN could be attributed to the fact that the photovoltage (PV) of the p–n junction promotes separation of the electron–hole pairs of the TiO2, and the holes are thus left within the TiO2 nanorods to produce a strong oxidant of hydroxyl radicals (˙OH). Moreover, this heterojunction device could be easily fabricated in a large size for easy recovery and recycling, which shows its promise in the solar-driven degradation of environmental pollution.

Herein, combining solverthermal route and electrodeposition, we grew unique hybrid nanosheet arrays consisting of Co3O4 nanosheet as a core, PPy as a shell. Benefiting from the PPy as conducting polymer improving an electron transport rate as well as synergistic effects from such a core/shell structure, a hybrid electrode made of the Co3O4@PPy core/shell nanosheet arrays exhibits a large areal capacitance of 2.11 F cm−2 at the current density of 2 mA cm−2, a ~4-fold enhancement compared with the pristine Co3O4 electrode; furthermore, this hybrid electrode also displays good rate capability (~65 % retention of the initial capacitance from 2 to 20 mA cm−2) and superior cycling performance (~85.5 % capacitance retention after 5000 cycles). In addition, the equivalent series resistance value of the Co3O4@PPy hybrid electrode (0.238 Ω) is significantly lower than that of the pristine Co3O4 electrode (0.319 Ω). These results imply that the Co3O4@PPy hybrid composites have a potential for fabricating next-generation energy storage and conversion devices.

We report on the development of 3D hierarchical NiCo2S4@MnO2 core–shell nanosheet arrays on Ni foam for supercapacitors. In our design, the highly conductive NiCo2S4 nanosheets can serve not only as a good pseudocapacitive material, which can be contributed to the capacitance of the whole electrode, but also as a 3D conductive scaffold for loading MnO2 materials, which can overcome the limited conductivity of MnO2 itself. Furthermore, the 3D NiCo2S4@MnO2 hybrid electrode can provide efficient and rapid pathways for ion and electron transport. These merits together with the elegant synergy between NiCo2S4 and MnO2 lead to a high areal capacitance of 2.6 F cm−2 at 3 mA cm−2 and good cyclic stability.

Design and fabrication of high performance pseudocapacitors from 3D hierarchical hybrid electrodes with large areal capacitance and excellent rate capability still remains a challenge. Here, 3D hierarchical hybrid mesoporous NiCo2O4@CoxNi1−x(OH)2 core–shell nanosheet arrays on Ni foam have been rationally designed and facilely synthesized via an electrodeposited routine for pseudocapacitor applications. Electrochemical measurements show that the NiCo2O4@Co0.33Ni0.67(OH)2 electrode material exhibits a large areal capacitance as high as 5.71 F cm−2 at a current density of ∼5.5 mA cm−2, as a result of our high mass loading up to ∼5.5 mg cm−2. Moreover, it exhibits an excellent rate capability (∼83.7% capacitance retention at 273 mA cm−2). Based on these excellent properties, an asymmetric supercapacitor based on 3D hierarchical hybrid mesoporous NiCo2O4@Co0.33Ni0.67(OH)2 nanosheet arrays as the positive electrode and CMK-3 as the negative electrode was successfully fabricated. The as-fabricated device achieved the maximum areal capacitance of 887.5 mF cm−2 (specific capacitance of 87.9 F g−1) at 5 mA cm−2 with a stable operational voltage of 1.6 V and a high energy density of 31.2 W h kg−1 at a power density of 396 W kg−1. Moreover, two asymmetric supercapacitors in series could power 5 mm diameter red round light-emitting diode (LED) indicators efficiently for more than 5 minutes. The present 3D hierarchical hybrid material electrode with remarkable electrochemical properties has significant potential applications in high energy density storage systems.

We demonstrate the design and fabrication of hierarchical mesoporous NiCo2O4@MnO2 core–shell nanowire arrays on nickel foam via a facile hydrothermal and electrodeposition process for supercapacitor applications. In order to increase the energy density and voltage window, a high-voltage asymmetric supercapacitor based on hierarchical mesoporous NiCo2O4@MnO2 core–shell nanowire arrays on nickel foam as the positive electrode and activated carbon (AC) as the negative electrode was successfully fabricated. The as-fabricated asymmetric supercapacitor device achieved a specific capacitance of 112 F g−1 at a current density of 1 mA cm−2 with a stable operational voltage of 1.5 V and a maximum energy density of 35 W h kg−1. The present NiCo2O4@MnO2 core–shell nanowire arrays with remarkable electrochemical properties could be considered as potential electrode materials for next generation supercapacitors in high energy density storage systems.

We have reported a facile, template-free and effective electrochemical method to grow MnO2 ultrafine nanobelts on Ni foam. Electrochemical measurements showed that the MnO2 nanobelt electrode exhibited an enhanced specific capacitance of 509 F g−1 at 200 mA g−1 at 50 °C. More importantly, the specific capacitance of the MnO2 nanobelt electrode nearly has 91.3% retention after 5000 cycles with repeated heating and cooling in the temperature range of 0 to 50 °C, showing good high temperature-resistive long-term cycle stability.

We present a simple strategy for synthesizing sponge-like NiCo2O4/MnO2 ultrathin nanoflakes, which exhibit a high specific capacitance of 935 F g−1 at 1 A g−1, excellent rate performance (74.9% retention at 50 A g−1), and ultra-long cycling stability (103.1% of the initial capacitance after 25000 cycles).

The molybdenum oxide nanosheets have shown strong localized surface plasmon resonance (LSPR) absorption in the near-infrared (NIR) region. However, the long alky chains of ligands made them hydrophobic and less biocompatible. To meet the requirements of molybdenum based nanomaterials for use as a future photothermal therapy, a simple hydrothermal route has been developed for hydrophilic molybdenum oxide nanospheres and nanoribbons using a molybdenum precursor and poly(ethylene glycol) (PEG). First, molybdenum oxide nanomaterials prepared in the presence of PEG exhibit strong localized surface plasmon resonance (LSPR) absorption in near-infrared (NIR) region, compared with that of no PEG. Second, elevation of synthetic temperature leads to a gradual transformation of molybdenum oxide nanospheres into nanoribbons, entailing the evolution of an intense LSPR absorption in the NIR region. Third, as-prepared molybdenum oxide nanomaterials coated with PEG possess a hydrophilic property and thus can be directly used for biological applications without additional post treatments. Moreover, molybdenum oxide nanoribbons as a model of photothermal materials can efficiently convert the 980 nm wavelength laser energy into heat energy, and this localized hyperthermia produces the effective thermal ablation of cancer cells, meaning a potential photothermal material.Keywords: localized surface plasmon resonance; Molybdenum oxide; morphology-controlled; photothermal;

The semiconductor compounds have been proven to be promising candidates as a new type of photothermal therapy agent, but unsatisfactory photothermal conversion efficiencies limit their widespread application in photothermal therapy (PTT). Herein, we synthesized cysteine-coated CuS nanoparticles (Cys-CuS NPs) as highly efficient PTT agents by a simple aqueous solution method. The Cys-CuS NPs have a good biocompatibility owing to their biocompatible cysteine coating and exhibit a strong absorption in the near-infrared region due to the localized surface plasma resonances of valence-band free carriers. The photothermal conversion efficiency of Cys-CuS NPs reaches 38.0%, which is much higher than that of the recently reported Cu9S5 and Cu2−xSe nanocrystals. More importantly, tumor growth can be efficiently inhibited in vivo by the fatal heat arising from the excellent photothermal effect of Cys-CuS NPs at a low concentration under the irradiation of a 980 nm laser with a safe power density of 0.72 W cm−2. Therefore, the Cys-CuS NPs have great potential as ideal photothermal agents for cancer therapy.

The rational synthesis and design of three-dimensional organic–inorganic hybrids still remain a challenge. A new ZGO-based 3D architecture was successfully fabricated via a facial and controllable hydrothermal method. Influence factors, e.g., feeding ratios, reaction temperature, reaction time show an obvious effect on the morphology of the obtained product. A solvent-coordination molecular template (SCMT) mechanism was proposed to understand the formation of three-dimensional nanobundles based on time-dependent experiments. The composites display a strong and wide emission in 405 and 431 nm, potentially applied in optoelectronic devices and other nanodevices.

In this work, one-dimensional CoMoO4·0.9H2O nanorods grown on reduced graphene oxide hybrid composites (CoMoO4·0.9H2O–rGO) with good electrochemical properties have been synthesized by a simple and environmentally friendly hydrothermal synthesis procedure. The conductive graphene not only improves the electron conductivity of the overall electrode but also provides strong synergistic effects with Faradaic pseudo-capacitance (CoMoO4·0.9H2O). Meanwhile, rGO can act as a buffer for the volume change, which can provide an assurance for better cycling performance of the CoMoO4·0.9H2O–rGO hybrid composites. An exceptionally high specific capacitance of 802.2 F g−1 at a current density of 1 A g−1 and good cycle stability with capacitance retention of ∼86.3% after 5000 cycles is obtained for the CoMoO4·0.9H2O–rGO composites. The remarkable electrochemical performance can make the CoMoO4·0.9H2O–rGO composites one of the most competitive electrode materials for electrochemical energy storage.

Single-crystalline Cu2−xSe nanowires with high aspect ratio on copper substrate have been achieved by a simple hydrothermal route. Based on in situ TEM studies, while utilizing integrated STM holder measuring their electrical conductivities, it is confirmed that single-crystalline Cu2−xSe nanowire was very good match the semiconducting characteristic. An electron source device using as-prepared Cu2−xSe nanowires on the Cu substrate has been first fabricated, which shows excellent field emission (FE) properties: the emitting current density as high as 0.83 μA/cm2 at an applied field of 5.5 V/μm, suggesting that the Cu2−xSe nanowire may be potentially applied in the vacuum microelectronics industry.

•Well-crystallized α-MoO3 nanobelts were prepared by a hydrothermal method.•MoO3/PANI coaxial nanobelts were carried out via a simple and green approach.•The coaxial heterostructure nanobelt shows superior supercapacitor performance.•A high specific capacitance of 714 F g−1 at 1 mV s−1 in 1 M H2SO4 electrolyte.A large-scale of MoO3/PANI coaxial heterostructure nanobelts have been fabricated for high-performance supercapacitors via a simple and green approach without any surfactant. Herein, the assembly of PANI conductive layer on the surface of the well-crystallized α-MoO3 nanobelts was carried out using ammonium persulfate (APS) as oxidant by in-situ polymerization at room temperature. As-prepared MoO3/PANI coaxial heterostructure nanobelts have been successfully employed as supercapacitor electrodes. It was found that the as-synthesized MoO3/PANI coaxial heterostructure nanobelts exhibited excellent supercapacitor performance with high specific capacitances of 714 F g−1 at a scan rate of 1 mV s−1 and 632 F g−1 at a current density of 1 A g−1 in 1 M H2SO4 electrolyte, whereas the original α-MoO3 nanobelts just showed initial specific capacitances of 275 F g−1 and 267 F g−1 at 1 mV s−1 and 1 A g−1, respectively, which attributed to the synergic effect between the PANI coating and the original α-MoO3 nanobelts.Novel MoO3/PANI coaxial heterostructure nanobelts fabricated on a large-scale by a simple and green approach without any surfactant exhibits high specific capacitance of 714 F g−1 at a scan rate of 1 mV s−1 and 632 F g−1 at a current density of 1 A g−1, as well as good cycling stability (76.7% of capacity retention after 3000 cycles).

•3D core/shell configuration of dense MnOOH ultrathin nanosheets grown on porous NiO nanosheets arrays via a facile synthetic route.•The core/shell configuration electrode material show superior supercapacitor performance.•A high specific capacitance of 1625.3 F/g, excellent energy density (80.0 Wh/kg), and good cycling stability (105.7 %).As the most promising electrode material for supercapacitors, core/shell hybrid material will enhance the electrochemical performance comparing with single component constituent, thus has recently drawn our research. Herein, we have designed and synthesized 3D hierarchical heterostructures of dense MnOOH ultrathin nanosheets grown on porous hierarchical NiO nanosheet arrays by facial and rational process. In this configuration, porous hierarchical NiO nanosheet arrays serve as fast ion and electron transport model and dense MnOOH ultrathin nanosheets enhance the contact surface area and assist ions penetrate into the core region to realize the release of potential electrochemical properties of NiO nanosheet arrays, and thus these heterostructures provide intense needed critical function for efficient use of metal oxide and hydroxide in energy storage. As an electrode, the as-fabricated 3D NiO@MnOOH core/shell nanosheet hierarchies exhibited favorable electrochemical performances, i.e., high specific capacitance of 1625.3 F/g at a current density of 4 A/g with a remarkable rate capability and excellent energy density (80.0 Wh/kg), as well as good cycling stability (105.7% of the initial capacitance after 5000 cycles). It suggests that they should have a promising potential for the next generation energy conversion–storage devices.A 3D core/shell configuration of dense MnOOH ultrathin nanosheets grown on porous NiO hierarchies as electrode material via a facile synthetic route exhibits high specific capacitance of 1625.3  F/g at a current density of 4 A/g with remarkable rate capability, excellent energy density (80.0  Wh/kg), as well as good cycling stability (105.7% of the initial capacitance after 5000 cycles).

A rational design has resulted in the large-scale synthesis of amorphous carbon coated mesoporous NiO (denoted as NiO@C) nanocomposites through a hydrothermal method. The mesoporous characteristics of as-synthesized NiO@C nanocomposites provide an ultrahigh active surface area and thus significantly enhance the intercalation of ions and the utilization rate of electrode materials, while the carbon shell within the nanocomposites improves greatly the electron conductivity of the overall electrode. Being beneficial for a strong synergistic effect between NiO and carbon materials, the mesoporous NiO@C nanocomposites as high-performance pseudocapacitors exhibited a high specific capacitance of 931 F g−1 at 2 A g−1 and a long-term cycling stability (∼7% loss after 6000 cycles), as compared with NiO (707 F g−1 at 2 A g−1 and ∼13% loss after 6000 cycles).

We demonstrate the design and fabrication of hierarchical mesoporous NiCo2O4@MnO2 core–shell nanowire arrays on nickel foam via a facile hydrothermal and electrodeposition process for supercapacitor applications. In order to increase the energy density and voltage window, a high-voltage asymmetric supercapacitor based on hierarchical mesoporous NiCo2O4@MnO2 core–shell nanowire arrays on nickel foam as the positive electrode and activated carbon (AC) as the negative electrode was successfully fabricated. The as-fabricated asymmetric supercapacitor device achieved a specific capacitance of 112 F g−1 at a current density of 1 mA cm−2 with a stable operational voltage of 1.5 V and a maximum energy density of 35 W h kg−1. The present NiCo2O4@MnO2 core–shell nanowire arrays with remarkable electrochemical properties could be considered as potential electrode materials for next generation supercapacitors in high energy density storage systems.

The semiconductor compounds have been proven to be promising candidates as a new type of photothermal therapy agent, but unsatisfactory photothermal conversion efficiencies limit their widespread application in photothermal therapy (PTT). Herein, we synthesized cysteine-coated CuS nanoparticles (Cys-CuS NPs) as highly efficient PTT agents by a simple aqueous solution method. The Cys-CuS NPs have a good biocompatibility owing to their biocompatible cysteine coating and exhibit a strong absorption in the near-infrared region due to the localized surface plasma resonances of valence-band free carriers. The photothermal conversion efficiency of Cys-CuS NPs reaches 38.0%, which is much higher than that of the recently reported Cu9S5 and Cu2−xSe nanocrystals. More importantly, tumor growth can be efficiently inhibited in vivo by the fatal heat arising from the excellent photothermal effect of Cys-CuS NPs at a low concentration under the irradiation of a 980 nm laser with a safe power density of 0.72 W cm−2. Therefore, the Cys-CuS NPs have great potential as ideal photothermal agents for cancer therapy.

Design and fabrication of high performance pseudocapacitors from 3D hierarchical hybrid electrodes with large areal capacitance and excellent rate capability still remains a challenge. Here, 3D hierarchical hybrid mesoporous NiCo2O4@CoxNi1−x(OH)2 core–shell nanosheet arrays on Ni foam have been rationally designed and facilely synthesized via an electrodeposited routine for pseudocapacitor applications. Electrochemical measurements show that the NiCo2O4@Co0.33Ni0.67(OH)2 electrode material exhibits a large areal capacitance as high as 5.71 F cm−2 at a current density of ∼5.5 mA cm−2, as a result of our high mass loading up to ∼5.5 mg cm−2. Moreover, it exhibits an excellent rate capability (∼83.7% capacitance retention at 273 mA cm−2). Based on these excellent properties, an asymmetric supercapacitor based on 3D hierarchical hybrid mesoporous NiCo2O4@Co0.33Ni0.67(OH)2 nanosheet arrays as the positive electrode and CMK-3 as the negative electrode was successfully fabricated. The as-fabricated device achieved the maximum areal capacitance of 887.5 mF cm−2 (specific capacitance of 87.9 F g−1) at 5 mA cm−2 with a stable operational voltage of 1.6 V and a high energy density of 31.2 W h kg−1 at a power density of 396 W kg−1. Moreover, two asymmetric supercapacitors in series could power 5 mm diameter red round light-emitting diode (LED) indicators efficiently for more than 5 minutes. The present 3D hierarchical hybrid material electrode with remarkable electrochemical properties has significant potential applications in high energy density storage systems.

We have reported a facile, template-free and effective electrochemical method to grow MnO2 ultrafine nanobelts on Ni foam. Electrochemical measurements showed that the MnO2 nanobelt electrode exhibited an enhanced specific capacitance of 509 F g−1 at 200 mA g−1 at 50 °C. More importantly, the specific capacitance of the MnO2 nanobelt electrode nearly has 91.3% retention after 5000 cycles with repeated heating and cooling in the temperature range of 0 to 50 °C, showing good high temperature-resistive long-term cycle stability.

We present a simple strategy for synthesizing sponge-like NiCo2O4/MnO2 ultrathin nanoflakes, which exhibit a high specific capacitance of 935 F g−1 at 1 A g−1, excellent rate performance (74.9% retention at 50 A g−1), and ultra-long cycling stability (103.1% of the initial capacitance after 25000 cycles).

Herein, we report a photocatalytic heterojunction device of rutile TiO2 nanorod arrays based on a p–n silicon junction (TiO2@PN) and its full absorption of ultraviolet and visible light for synergistic photodegradation. The fabricated TiO2@PN had excellent photocatalytic degradation of methyl orange (MO) under irradiation of a 300 W Xe lamp, and its pseudo-first-order rate constant k was 0.221 h−1, which was greatly higher than that for TiO2 nanorod arrays based on an n–p silicon junction (TiO2@NP, 0.078 h−1) and glass (TiO2@G, 0.032 h−1). The higher photocatalytic performance of TiO2@PN could be attributed to the fact that the photovoltage (PV) of the p–n junction promotes separation of the electron–hole pairs of the TiO2, and the holes are thus left within the TiO2 nanorods to produce a strong oxidant of hydroxyl radicals (˙OH). Moreover, this heterojunction device could be easily fabricated in a large size for easy recovery and recycling, which shows its promise in the solar-driven degradation of environmental pollution.