Nano Arrays Research Articles

Hot Carrier Generation and Extraction from Slow Photons

Plasmonic nanostructures, characterized by localized surface plasmon resonance (LSPR), facilitate strong interactions with light and induce collective oscillations of conduction band electrons on metal nanoparticle surfaces. This process enhances light absorption and promotes the generation of hot carriers. However, their energy conversion efficiency is often limited by challenges such as rapid charge recombination and restricted light absorption. We integrated Ag nanoparticles (NPs) with periodically ordered SrTiO3/TiO2 nanoarrays (NAs). These NAs create photonic stopbands, that were precisely aligned to coincide with the LSPR band of the Ag NPs. This configuration confines light effectively within the structure, thereby enhancing the LSPR-induced electron generation. The stepwise structure of SrTiO3/TiO2 further facilitated the efficient collection of these energetic electrons. This synergistic combination of plasmonic and photonic elements resulted in a substantial improvement in non-equilibrium electron harvesting efficiency. Under LSPR excitation at 500 nm, a rate of 3.1 × 10⁻⁴ electrons per absorbed photon was achieved. The findings demonstrate a strategy for harnessing plasmon energy, with potential applications in fields such as photocatalysis and photovoltaics.

Target Recognition-Triggered Interfacial Electron Transfer Model: Toward Signal-On Photoelectrochemical Aptasensing for Efficient Detection of Staphylococcus aureus Using Ti3C2Tx-Au NBPs/ZnO NR Composites.

Staphylococcus aureus (S. aureus) is one of the most common foodborne pathogens worldwide, which poses a great threat to public health. It is of utmost importance to develop rapid, simple, and sensitive methods for the determination of S. aureus. A signal-on photoelectrochemical (PEC) aptasensor is constructed herein based on titanium carbide (Ti3C2Tx)-Au nanobipyramids (NBPs)/ZnO nanoarrays (NRs). The reliability and capability of the PEC aptasensor make it suitable for the sensitive and selective determination of S. aureus. First, the electrostatically self-assembled Ti3C2Tx-Au NBP nanomaterial was coated on the ZnO NR surface by a spin-coating method. On the one hand, Ti3C2Tx-Au NBPs can broaden the spectral absorption of ZnO NRs, resulting in Ti3C2Tx-Au NBPs/ZnO NR composites that exhibit a wide range of absorption from the ultraviolet to the infrared region. On the other hand, Ti3C2Tx can reduce the agglomeration of nanoparticles, while Au NBPs can effectively fix the aptamer through the Au-S bond. Specifically, the experimental results show that when S. aureus is present, the Au NBPs-aptamer-S. aureus complex is shed from the electrode surface, altering the interfacial electron transfer model and reducing the steric hindrance. Consequently, an amplified photocurrent signal for the quantitative determination of S. aureus is obtained. Under optimal experimental conditions, a linear correlation is observed between the current response of the aptasensor and the logarithm of the S. aureus concentration (ranging from 1.0 to 1.0 × 106 CFU/mL), with an impressive detection limit as low as 0.5 CFU/mL. Furthermore, the aptasensor has been successfully employed for the detection of S. aureus in milk, with the recovery of 93.0%-99.0%. Hence, this research offers a novel approach for the detection of foodborne pathogens and other noxious substances.

Surface Functionalization of 3D-Printed Scaffolds with Seed-Assisted Hydrothermally Grown ZnO Nanoarrays for Bone Tissue Engineering.

Bioactive metal-based nanostructures, particularly zinc oxide (ZnO), are promising materials for bone tissue engineering. However, integrating them into 3D-printed polymers using traditional blending methods reduces the cell performance. Alternative surface deposition techniques often require extreme conditions that are unsuitable for polymers. To address these issues, we propose a metal-assisted hydrothermal synthesis method to modify 3D printed polycaprolactone (PCL) scaffolds with ZnO nanoparticles (NPs), facilitating the growth of ZnO nanoarrays (NAs) at a low-temperature (55 °C). Physicochemical characterizations revealed that the ZnO NPs form both physical and chemical bonds with the PCL surface; chemical bonding occurs between the carboxylate groups of PCL and Zn(OH)2 during seed deposition and hydrothermal synthesis. The ZnO NPs and NAs grown for a longer time (18 h) on the surface of PCL scaffolds exhibit significant proliferation and early differentiation of osteoblast-like cells. The proposed method is suitable for the surface modification of thermally degradable polymers, opening up new possibilities for the deposition of diverse metals.

ZnO nanoarrays/Cu nanowires composite films with high haze value

In this work, we worked on compositing Cu nanowires (NWs) with ZnO nanoarrays (NAs) to enhance the light trapping abilities of transparent conductive films. A well-dispersed, crosslinked network of Cu NWs with appropriate light trapping ability was formed on the surface of the ZnO NAs, and the ZnO NAs/Cu NWs composite structures were obtained ultimately. The Cu NWs on the surface of the composite structures maintained excellent transparency and conductivity while preventing agglomeration phenomena. The ZnO NAs/Cu NWs composite films exhibited low average sheet resistance (59 Ω/sq) and high haze value (0.53) at 550 nm with uniform conductivity and exceptional light trapping performance. The composite films not only demonstrate enhanced light trapping abilities, but also exhibit improved electrical properties, making it an outstanding candidate for transparent front electrode materials in solar cell applications.

In-situ synthesis of MEMS compatible Al/Cu2HIO6/PVDF Metastable composites film with high combustion performance

To address the challenges related to significant pressure loss and weakened combustion performance of energetic materials when ignited on Micro-Electro-Mechanical Systems (MEMS), periodate-based MICs (Metastable Intermolecular Composites) have emerged as promising candidates due to their high energy density and combustion pressure. However, the integration of periodate-based MICs onto MEMS has not been effectively achieved thus far. Herein, we propose a simple, environmentally friendly, and cost-effective approach to fabricate a MEMS-compatible Al/Cu2HIO6/PVDF (polyvinylidene difluoride) energetic composite film. Our method involves utilizing a Cu(OH)2 array as a template and employing an in-situ and spin-coating process. The resulting Al/Cu2HIO6/PVDF film was characterized using various techniques including SEM, TEM, XRD, and XPS. These analyses reveal a tightly packed nano array morphology with a porous structure. DSC-TG analysis was conducted to investigate the thermal reaction of the Al/Cu2HIO6/PVDF composite film. The results demonstrate that the thermal reaction involved a complex multi-step process, with higher heat release (1121 J g-1), a faster reaction rate, and a lower initial reaction temperature (294.5 °C) compared to the Al/CuO/PVDF composite film. the reaction process of Al/Cu2HIO6/PVDF film was also been proposed by analyzing the products at different temperatures. combustion diagnostic tests were carried out to evaluate the combustion performance of the Al/Cu2HIO6/PVDF composite film. The results indicate that as CuO transformed into Cu2HIO6, the film exhibits a reduced ignition delay (8 ms) and combustion duration (50 ms), higher combustion temperature (3710 K), and stronger flame intensity (8630 a.u.).

Ni/WS2/WC Composite Nanosheets as an Efficient Catalyst for Photoelectrochemical Hydrogen Peroxide Sensing and Hydrogen Evolution.

It is highly attractive to develop a photoelectrochemical (PEC) sensing platform based on a non-noble-metal nano array architecture. In this paper, a PEC hydrogen peroxide (H2O2) biosensor based on Ni/WS2/WC heterostructures was synthesized by a facile hydrothermal synthesis method and melamine carbonization process. The morphology, structural and composition and light absorption properties of the Ni/WS2/WC catalyst were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and UV-visible spectrophotometer. The average size of the Ni/WS2/WC nanosheets was about 200 nm. Additionally, the electrochemical properties toward H2O2 were studied using an electrochemical workstation. Benefiting from the Ni and C atoms, the optimized Ni/WS2/WC catalyst showed superior H2O2 sensing performance and a large photocurrent response. It was found that the detection sensitivity of the Ni/WS2/WC catalyst was 25.7 μA/cm2/mM, and the detection limit was 0.3 mmol/L in the linear range of 1-10 mM. Simultaneously, the synthesized Ni/WS2/WC electrode displayed excellent electrocatalytic properties in hydrogen evolution reaction (HER), with a relatively small overpotential of 126 mV at 10 mA/cm2 in 0.5 M H2SO4. This novel Ni/WS2/WC electrode may provide new insights into preparing other efficient hybrid photoelectrodes for PEC applications.

Thermoelectrically Driven Dual-Mechanism Regulation on SERS and Application Potential for Rapid Detection of SARS-CoV-2 Viruses and Microplastics.

Electric-induced surface-enhanced Raman scattering (E-SERS) has been widely studied for its flexible regulation of SERS after the substrate is prepared. However, the enhancement effect is not sufficiently high in the E-SERS technology reported thus far, and no suitable field of application exists. In this study, a highly sensitive thermoelectrically induced SERS substrate, Ag/graphene/ZnO (AGZ), was fabricated using ZnO nanoarrays (NRs), graphene, and Ag nanoparticles (NPs). Applying a temperature gradient to the ZnO NRs enhanced the SERS signals of the probe molecules by a factor of approximately 20. Theoretical and experimental results showed that the thermoelectric potential enables the simultaneous modulation of the Fermi energy level of graphene and the plasma resonance peak of Ag NPs, resulting in a double enhancement in terms of physical and chemical mechanisms. The AGZ substrate was then combined with a mask to create a wearable thermoelectrically enhanced SERS mask for collecting SARS-CoV-2 viruses and microplastics. Its SERS signal can be enhanced by the temperature gradient created between a body heat source (∼37 °C) and a cold environment. The suitability of this method for virus detection was also examined using a reverse transcription-polymerase chain reaction and SARS-CoV-2 virus antigen detection. This work offers new horizons for research of E-SERS, and its application potential for rapid detection of the SARS-CoV-2 virus and microplastics was also studied.

High performance self-powered ultraviolet photodetectors based on P(TTh-co-EDOT) copolymer sensitized TiO2 NRs

A self-powered ultraviolet photodetector (UV PD) effectively utilizes UV energy and has attracted greatly attention due to its no consuming of any external power. In this work, TiO2 nanoarrays (NRs) were synthesized by a one-step hydrothermal method, which was combined with P(TTh-co-EDOT) to realize a high-performance p-n heterojunction UV PD, and P(TTh-co-EDOT) was evaluated as the photosensitive layers in UV PDs for the first time. Furthermore, the working mechanism for the self-powered of UV PD was discussed in detail based on the energy band theory. Different electrochemical deposition cycles of TTh-co-EDOT on the surface of TiO2 NRs were applied to form p-n heterojunction for achieving the optimum photoelectric performance. Among them, it was found that the optimum UV PD based on face-to-face fabrication of TiO2 NRs and P(TTh-co-EDOT) from 3 deposition cycles exhibits an enhancement of photoelectric performance without applying any external voltage. Benefiting from the enhanced built-in electric field of the TiO2 NRs/P(TTh-co-EDOT) interface, balancing photogenerated carriers and the charge separation and transport in self-power mode, the responsivity and detectivity of TiO2 NRs/P(TTh-co-EDOT)-3C are 2.252 mA/W and 3.413 × 1010 Jones, with the rise and fall times are 0.256/0.427 s, which exhibited excellent photoelectric properties and stability. TiO2 NRs/P(TTh-co-EDOT)-1C has the lowest responsivity (0.0995 mA/W) and detectivity (6.035 × 109 Jones) and TiO2 NRs/P(TTh-co-EDOT)-4C has the longest rise and fall times (0.460/0.451 s). These results suggest that the great potential of the TiO2 NRs and P(TTh-co-EDOT) for high-performance UV PDs.

3D integrated non-noble metal oxides nano arrays for enhanced nitrate electroreduction to ammonia

The electrochemical nitrate reduction reaction (eNO3RR) to ammonia (NH3) is a promising alternative method to the Haber-Bosch process that requires high temperature and pressure. In this contribution, the integrated Co3O4 nanowire arrays on Ni foam (Co3O4/NF) are reported to exhibit the outstanding performance with a high NH3 yield rate of 117.01 mg h−1cm−2, a superior NH3 Faradaic efficiency of 99.28 %, a high effective current density of 1475.71 mA cm−2, and a good operation durability during 40 consecutive recycling tests (40 h) in 1.0 M NaOH (0.1 M NaNO3). The high-valence metal cations as electron-deficient centers can act as Lewis-acid sites, favorably interacting with the Lewis base NO3−, and accordingly boosting the NO3− adsorption and activation. Moreover, the in-situ growth array configuration provides the substantial active sites and constructs a fast electron-transport channel, thus facilitating the conversion of NO3−-to-NH3. Density functional theory (DFT) calculations also reveal that the Co atoms as the active sites are preferred to adsorb NO3−, implying that the NO3− electroreduction dominates the cathodic reaction rather than hydrogen evolution reaction. This study provides a viable method to design integrated electrodes with enhanced eNO3RR activity and selectivity, which might have broad prospects in the application of renewable energy.

Self‐Powered Piezo‐Supercapacitors Based on ZnO@Mo‐Fe‐MnO2 Nanoarrays

The development of self‐charging supercapacitor power cells (SCSPCs) has profound implications for smart electronic devices used in different fields. Here, we epitaxially electrodeposited Mo‐ and Fe‐codoped MnO2 films on piezoelectric ZnO nanoarrays (NAs) grown on the flexible carbon cloth (denoted ZnO@Mo‐Fe‐MnO2 NAs). A self‐charging supercapacitor power cell device was assembled with the Mo‐ and Fe‐codoped MnO2 nanoarray electrode and poly(vinylidenefluoride‐co‐trifluoroethylene) (PVDF‐Trfe) piezoelectric film doped with BaTiO3 (BTO) and carbon nanotubes (CNTs) (denoted PVDF‐Trfe/CNTs/BTO). The self‐charging supercapacitor power cell device exhibited an energy density of 30 μWh cm−2 with a high power density of 40 mW cm−2 and delivered an excellent self‐charging performance of 363 mV (10 N) driven by both the piezoelectric ZnO nanoarrays and the poly(vinylidenefluoride‐co‐trifluoroethylene) piezoelectric film doped with BaTiO3 and carbon nanotubes. More intriguingly, the device could also be self‐charged by 184 mV due to residual stress alone and showed excellent energy conversion efficiency and low self‐discharge rate. This work illustrates for the first time the self‐charging mechanism involving electrolyte ion migration driven by both electrodes and films. A comprehensive analysis strongly confirmed the important contribution of the piezoelectric ZnO nanoarrays in the self‐charging process of the self‐charging supercapacitor power cell device. This work provides novel directions and insights for the development of self‐charging supercapacitor power cells.

Light absorption by a planar array of spherical particles and a matrix in which they are embedded: statistical approach.

The fractions of light energy absorbed by a 2D array of spherical particles and the matrix in which they are embedded are determined. The solution is based on a volume integral equation and a statistical approach. The absorption coefficient of the array is found via the internal fields of the particles. The absorption coefficient of a matrix is found as the difference between the absorption coefficients of the composite structure and the particles. Numerical results are presented for arrays of metal, semiconductor, and dielectric nano- and microparticles of short-range order and imperfect long-range order in the absorbing media at normal and oblique incidence of a plane wave.

Photovoltaic–Pyroelectric coupled effect enhanced photo-responsivity of a p-n heterojunction Self-Powered ultraviolet photodetector

TiO2-based ultraviolet (UV) photodetectors (PDs) with broadband optical detection range are widely used in commercial and military applications. Nevertheless, the self-powered UV PDs of TiO2 nanoarrays (NRs) have relatively low response rates and slow response times. Here, a high responsivity self-powered p-n heterojunction UV PD based on TiO2 NRs: CQDs/FTO and PEDOS/FTO is fabricated by a simple face-to-face assembly process. The pyroelectric effect of TiO2 NRs is enhanced by sensitizing TiO2 NRs with CQDs, which would reduce the bandgap value of TiO2 NR, broaden the range of photoresponse, and reduce recombination of electron-hole. Furthermore, the pyro-phototronic effect of CQDs, the energy level matching from CQDs to PEDOS and the interaction between –OH in CQDs and ethylene oxide groups in PEDOS enhance the performance of the prepared UV PDs. The TiO2 NRs: CQDs//PEDOS UV PDs achieve a high photo-responsivity and photo-detectivity of 150.95 mA/W and 3.73 × 1011 Jones at 0 bias (365 nm), respectively, which are better than those at wavelengths of 380 nm. We also found that the photocurrent induced via the pyro-phototronic effect increases with the light power intensity. This work points the way for photovoltaic and photo-induced pyro-phototronic effects to improve the performance of TiO2 NRs-based UV PDs.

Arrays of nano and micro inverted silicon structures via copper catalyzed chemical etching for effective light trapping

Nano/micro structuring of silicon (Si) via chemical approaches have currently acquired a lot of research interests owing to their excellent light trapping abilities in broad spectral range. Here, a comprehensive study on the fabrication of nano/micro-inverted structures via one-step copper (Cu) catalyzed chemical etching (CuCCE) of solar grade n-Si wafers employing the aqueous solution of Cu(NO3)2/HF/H2O2 in various compositions and their light trapping ability are reported. Influence of etch parameters, namely, Cu2+ ions concentration, HF/H2O2 compositions and surface properties of the wafers are systematically investigated on the evolution of different inverted nano- and micro-structured Si surfaces. Arrays of micron-sized inverted pyramids (μ-IP) and nano-micro-hybrid inverted pyramids (n-μ-HIP) have been fabricated on partial polished and as-cut solar grade Si wafers respectively in an optimized compositions of the solution (Cu(NO3)2, HF and H2O2 at 5 mM, 4.6 M and 0.55 M respectively) at 50 °C after 15 min. The surfaces exhibit solar weighted reflection as low as <7% and <5% respectively for a broad spectral range (400–1000 nm; AM1.5G). The n-μ-HIP-Si arrays also exhibited ∼8 fold enhanced Raman signal. Isotropic thinning of Si wafers, nano-porous, and craters like Si structures could also be obtained under appropriate etch conditions. Mechanism of the formation of such inverted structures under different etch conditions have been explained based on the Cu catalyzed, self-controlled electrochemical redox reactions and balancing act of anisotropic-isotropic etching of Si in the CuCCE etch bath. The excellent light trapping properties of the nano/micro structures is also explained. Moreover, the ‘proof of concept’ of application of the inverted nano/micro light trapping structures in the PEDOT:PSS/n-Si hybrid heterojunction solar cells with enhanced performance has also been shown. The Si surfaces via simple yet effective CuCCE process may find applications in other photosensitive devices as well as surface enhanced Raman spectroscopy.

TiO2 Passivated Zno Nanoarray Layer Based Fluoroalkylsilane Film for Photovoltaic Optical Glass: Achieving UV Shielding, Acid Rain Resistance, and Self‐Cleaning Properties

AbstractPhotovoltaic technology is a prominent source of renewable energy, but maintenance costs and efficiency attenuation of large photovoltaic devices are significant issues due to their vast energy conversion area. To reduce costs and facilitate maintenance, superhydrophobic surfaces with self‐cleaning properties have been developed for photovoltaic glass. In this study, transparent ZnO nanoarrays (NAs) are synthesized on photovoltaic glass, with Eu3+ doping enhancing the ultraviolet radiation resistance of photovoltaic devices and slightly increasing visible transmittance. A TiO2 passivation layer is introduced on the ZnO NAs surface to enhance acid resistance and mitigate corrosion caused by acidic rainwater. Fluoroalkylsilane (POTS) modification achieves superhydrophobicity with a water contact angle of 160.25°, as demonstrated by droplet rolling experiments. Micro‐interaction of superhydrophobic properties is further investigated by force curve measurement using atomic force microscope, showing almost no nanometer water moisture on the superhydrophobic surface, but conspicuous water moisture on the control glass surface. Finally, simulated models and practical silicon crystal solar cells fabricated using the self‐cleaning glass show excellent acid rain resistance, self‐cleaning, and long service life properties, with no power conversion efficiency degeneration during a 40‐day outdoor application test.

Electrospun Nanofibers as Chemosensors for Detecting Environmental Pollutants: A Review

Electrospun nanofibers have shown their advantages for applications in a wide variety of scientific fields thanks to their unique properties. Meanwhile, electrospinning is closely following the fast development of nano science and nanotechnology to move forward to smaller (pico-technology), more complicated nanostructures/nanodevices and more order (all kinds of nano arrays). Particularly, multiple-fluid electrospinning has the strong capability of creating nanostructures from a structural spinneret in a single-step and a straightforward “top-down” manner, holding great promise for creation on a large scale. This review is just to conclude the state-of-art studies on the related topics and also point out that the future directions of environmental detection require chemosensors, while the improvement of sensors requires new chemically synthesized functional substances, new nanostructured materials, application convenience, and functional integration or synergy. Based on the developments of electrospinning, more and more possibilities can be drawn out for detecting environmental pollutants with electrospun nanostructures as the strong support platform.

Two-dimensional polarization beam splitter based on cylindrical nano grating

In this paper, we report on a two-dimensional (2D) reflective grating with excellent polarization selectivity and high diffraction efficiency (DE). Based on silver cylindrical nano arrays, the grating is calculated by rigorous coupled wave analysis (RCWA). Optimized results show that the energy of transverse electric (TE) polarization is diffracted into (0, ±1) reflection orders and the energy of transverse magnetic (TM) polarization is diffracted into (±1, 0) reflection orders under normal incidence at 780 nm incident wavelength, with extinction ratio (ER) over 30 dB. To the best of our knowledge, this is the first time that a two-dimensional polarization beam splitter (2D-PBS) based on 2D grating is proposed, which opens up a new direction for the development of PBS. The holographic exposure technology, dry etching, and electron beam evaporation were used to fabricate the 2D-PBS. Preliminary experiments indicate that the 2D grating is sensitive to the polarization states of incident light and can be applied in the wide field of optical communication, high precision displacement measurement, and so on.

A Review on Fabrication and Application of Tunable Hybrid Micro–Nano Array Surfaces

AbstractThe wettability and adhesion of biological surfaces often depend on their periodically arranged hybrid micro–nano array structures. Various fabrication processes are designed to mimic biomimetic micro–nano array surfaces. This review summarizes the types of micro–nano array structures and analyzes fabrication methods based on top‐down and bottom‐up construction, including templating, etching, self‐assembly, and electrospinning/electrospraying. This review focuses on the shape reconfiguration of surface micro–nano array structures under physical stimuli, as well as the changes in material surface properties during the reconfiguration process. In addition, the applications of biomimetic micro–nano array composite surfaces in the fields of droplet transport, adhesion properties, sensors, and soft robotics are also discussed, and the current challenges and prospects in this field are identified.

Facile preparation of CuO nanoplate arrays film on Si substrate and their photoelectric characteristics

• A large scale CuO film is prepared on Si substrate tightly by ozone etching and annealing. • The film consists of a dense polycrystalline nanoplate array. • The film is fabricated into a schottky contacted diode with Al electrodes. • The diode performs a large rectifying ratio and a highly sensitive. Schottky contacted sensors are of promising photoelectric devices due to the intrinsic high selectivity and high sensitivity properties. However, it is still a challenge to construct a stable contacted semiconductor material in Schottky sensors. In this work, a CuO film was prepared by an ozone etching and annealing on a silicon wafer substrate. Material characteristic investigation shows that the film composed of a highly dense polycrystalline nanoplate arrays film. The film is also used to fabricate a schottky diode with aluminum electrode to test its photoelectric performance. The test results indicate that the diode has a large rectifying ratio and a highly sensitive photoreponse effect. This work provides a new facile CuO nano arrays material process for Schottky contacted sensor application.

High performance ultraviolet A/ultraviolet C detector based on amorphous Ga2O3/ZnO Nanoarrays/GaN structure

High-performance ultraviolet (UV) photodetector was fabricated based on amorphous Ga 2 O 3 /ZnO nanoarrays(NRs) on p-GaN film. The obtained detector displays excellent UV sensing properties which covers UV-A/UV-C region with fast response without external bias. The high photosensitivity can be ascribed to the geometry of the match-like Ga 2 O 3 /ZnO NRs and emergence of the built-in field between the amorphous Ga 2 O 3 and ZnO interface. The results will provide a new method to improve the ZnO/GaN heterostructure for applications in broadband ultraviolet sensing. High-performance ultraviolet (UV) photodetector was fabricated based on amorphous Ga 2 O 3 /ZnO nanoarrays(NRs) on p-GaN film. The obtained detector displays excellent UV sensing properties which covers UV-A/UV-C region with fast response without external bias. The high photosensitivity can be ascribed to the geometry of the match-like Ga 2 O 3 /ZnO NRs and emergence of the built-in field between the amorphous Ga 2 O 3 and ZnO interface. The results will provide a new method to improve the ZnO/GaN heterostructure for applications in broadband ultraviolet sensing. • Amorphous Ga2O3/ZnO NRs/GaN photodetector were fabricated by combining aqueous method and sputtering method. • The ZnO/GaN response performance is improved by depositing amorphous Ga2O3 layer. • The device has an excellent response in the ultraviolet A and ultraviolet C regions without external bias.

The effect of calcination temperature on the hydrogen evolution reaction performance of Co/NiCoP nano-heterojunction

The energy crisis makes it a challenge to develop cost-effective, efficient and stable electrocatalysts for hydrogen evolution reaction (HER). In this study, Co/NiCoP nano-heterojunctions grown on carbon cloth were reported for the first time through an electrochemical deposition - phosphatization strategy. Moreover, the effects of calcination temperature (300, 350, 400 and 450 °C) on the structure and morphology of the products were studied. The results reveal that: (a) Co/NiCoP with the morphology of nanoparticles (NPs) and nanoarrays (NAs) were fabricated under 300–350 °C and 450 °C, respectively; (b) increasing the calcination temperature lead to a decrease in the degree of crystallinity of Co/NiCoP catalysts, which was demonstrated by X-ray diffraction and X-ray photoelectron spectroscopy; (c) benefiting from structure and electronic state of electrocatalysts, the catalyst that is calcined at 350 °C ( Co/NiCoP-350 NPs) is optimal for HER in alkaline media, it required only 54 mV overpotential to achieve a current density of − 10 mA cm−2. Furthermore, the good stability of Co/NiCoP-350 NPs for HER in alkaline media.