Drop-coating Method Research Articles

Study of a fluorine-free silane-based film on an aluminum alloy via drop-coating method with the purpose of providing hydrophobic and corrosion protection properties

This work sought to developed a fluorine-free, water-repellent silane-based film on 5052 aluminum alloy by studying the incorporation of Hexadecyltrimethoxysilane (HDTMS) into or over the silica gel film to protect against corrosion in a saline environment. Additionally, the interface of the silane-based film was studied using liquids such as soybean oil, diesel oil, and lubricating oil. Silica gel particles were deposited by dripping a solution of silica gel using design of experiment approach. The porosity of the silica gel film was assessed employing the potentiodynamic polarization technique. The condition of the more cohesive silica gel film was chemically modified by dripping a low concentration solution of HDTMS. The functionalized film on the aluminum alloy exhibited a contact angle of 136°, oleophilic behavior for soybean oil and lubricating oil, and superoleophilic character for diesel oil. Notably, hydrophobic film exhibited chemical (acid, alkaline, saline) and thermal stabilities (50–150 °C). The protective effect of the functionalized film against corrosion ions was confirmed by Electrochemical Impedance Spectroscopy in a saline solution over 7 days. These results suggest a fluorine-free alternative approach for thin film development and the study of its multifunctionality, including enhanced corrosion resistance, water-diesel oil separation, and potential applications in anti-fouling.

Superhydrophobic/superoleophilic polyurethane /reduced graphene oxide/ sponge for efficient oil-water separation and photothermal remediation

Due to the rapid development of global industrialization, the frequent occurrence of organic matter leakage and oil leakage accidents has led to increasingly serious environmental pollution. Therefore, this paper has proposed a facile and affordable method for creating oil water separation materials, and successful creating a super hydrophobic/super oleophilic functional porous polyurethane sponge modified by reduced graphene oxide and polydopamine (PDA-rGO-PU). Dopamine undergoes a self-polymerization event that creates polydopamine, which is subsequently coated on a polyurethane framework to create a sponge structure with several active sites. The surface of the modified sponge structure was coated with graphene oxide by a simple drop-coating method, and graphene oxide coated on the surface of polydopamine was reduced to create the superhydrophobic/superoleophilic material. The PDA-rGO-PU demonstrated strong anti-adhesion properties and a high oil-water separation efficiency of 99.8 % while having high water contact angles of 155 ° ± 3 ° and oil contact angles (OCA) of 0 °. It has a strong ability to adsorb various oils and organic solvents, the excellent photothermal effect allows PDA-rGO-PU to raise temperature by 37.9 % in the presence of light. PDA-rGO-PU has good continuous oil sorption performance after installing the pump. When under simulated lighting conditions, the sorption time of modified sponge on crude oil was shortened by 2.3 times.

Enhancing the performance of self-powered heterojunctional ZnO/Cs3Bi2I9 photodetectors through pyroelectric-photovoltaic coupling effect

Bismuth (Bi)-based perovskites are promising materials for near-ultraviolet-to-visible light (NUV–vis) detection. However, their practical application has been limited by relatively weak responsivity and detectivity. In this study, we developed a large-area, low-cost, environmentally friendly self-powered NUV–vis photodetector based on a ZnO/Cs3Bi2I9 heterojunction through a simple drop-coating method. Leveraging the pyroelectric effect, the device demonstrates a high responsivity of 10.48 mA/W, specific detectivity of 7.69 × 1010 Jones, and a fast rise time of 0.9 ms. Moreover, we elucidated the physical mechanism of the self-powered NUV–vis photodetector and systematically analyzed the influence of light power density on photoresponse and response time. This study introduces an effective strategy to enhance the performance of Bi-based perovskite photodetectors under zero voltage bias, leveraging the pyroelectric effect induced in ZnO under ultraviolet illumination and the photovoltaic effect of the Cs3Bi2I9 perovskite. The newly designed ultra-fast self-powered NUV–vis photodetector holds significant promise for diverse research and commercial applications.

Nanoarchitecturing of Mo2C nanospheres on carbon cloth as an electrochemical sensing platform for determination of caffeic acid in tea samples

In the present paper, carbon cloth (CC) as a flexible substrate was modified by molybdenum carbide nanospheres (Mo2C NSs @CC) by the drop-coating method to develop a sensitive electrochemical platform for detecting caffeic acid. The uniform Mo2C NSs were prepared via an easy route followed by pyrolyzing the precursor of the Mo-polydopamine (Mo-PDA) NSs. The Mo2C NSs were characterized and analyzed by X-ray diffraction (XRD), field emission scanning electron microscopy/energy dispersive X-ray spectroscopy (FE-SEM/EDS), Raman spectroscopy (RS), and electrochemical methods. CC not only gave a flexible feature to the sensor but also provided a larger surface area for Mo2C NSs. Meanwhile, the excellent conductivity and large electroactive specific surface area of Mo2C NSs exhibited excellent electrocatalytic performance for caffeic acid determination. The developed sensor showed high sensitivity and selectivity, good reproducibility, and long-term stability with a limit of detection (LOD) and a wide linear range of 0.001 μM (S/N = 3) and 0.01–50 μM, respectively. In addition, the Mo2C NSs @CC sensor showed a promising application prospect for the detection of caffeic acid in green and black tea samples, indicating its importance in food safety and the food industry.

Toluene sensing properties of YSZ-based gas sensors attached with Au-based electrodes prepared by a drop-coating method

Toluene sensing properties of YSZ-based gas sensors attached with Au-based electrodes prepared by a drop-coating method

One-step construction of MWCNTs@MoS2@Chitosan film for ciprofloxacin sensing and its oxidation mechanism

Ciprofloxacin (CIP), extensively used in medical, agricultural, and forestry sectors as an antibiotic, poses risks of water contamination due to misuse or improper disposal, highlighting the pressing necessity for accelerated detection methods. Hydrophilic multi-walled carbon nanotubes (MWCNTs) and molybdenum disulfide (MoS2) were co-dispersed in a chitosan (CS) solution, which facilitates film formation. The high specific surface area of MWCNTs, coupled with the excellent semiconducting properties of MoS2 and the overall hydrophilicity of the composite nanomaterial film, markedly increases the active sites and reaction contact area. Subsequently, a drop-coating method was used to fabricate a MWCNTs@MoS2@Chitosan film onto the surface of a glassy carbon electrode (GCE) for CIP detection spanning from 0.50 to 1200.00 µmol/L using Differential Pulse Voltammetry (DPV), achieving a limit of detection (LOD) of 0.16 µmol/L. Simultaneously, the sensor demonstrates excellent reproducibility, stability, and selectivity. In several real water samples, the sensor performance was verified using a spiked recovery method. And in three water samples the recoveries ranged from 98.38 to 113.53 %, with a relative standard deviation (RSD) of less than 4.80 %. Meanwhile, the accuracy of these result was verified using UV–visible (UV–vis) spectroscopy. Furthermore, we proposed an electrooxidation mechanism for CIP that involves a reaction with two electrons and two protons.

Differential detection of NH3 and NO2 by polymer non-covalently encapsulated semiconducting single-walled carbon nanotubes

Semiconductor single-walled carbon nanotubes (sc-SWCNTs) exhibit exceptional optoelectronic properties and possess a substantial specific surface area, rendering them highly promising materials for the development of gas sensors with increasing the sensitivity and portability. In this study, we synthesized polymer bearing two Schiff base side chains (PF2L) via the Suzuki coupling reaction with enhanced polymer solubility. The sc-SWCNTs were selectively sorted using PF2L from commercially available SWCNTs to prepare PF2L/sc-SWCNTs composites. The incorporation of side chains enhanced the π-π interactions within the polymers and facilitated the interactions between the polymers and SWCNTs, thereby promoting superior dispersion of sc-SWCNTs. The PF2L/sc-SWCNTs-based sensors were fabricated using the drop-coating method, and their gas sensing performance was evaluated for gases with distinct properties (reducing: NH3 and oxidizing: NO2). The sensor exhibits a response of 2.415 % and 14.85 % for 1 ppm NH3 vapor and 1 ppm NO2, respectively. The sensor shows response and recovery times of 50 s and 220 s, respectively, for the detection of 1 ppm NH3 vapor, while it demonstrated response and recovery times of 59 s and 733 s for the detection of 1 ppm NO2. Subsequently, we developed an LED-based detection device for the selective discrimination of NH3 vapor and NO2, thereby offering valuable insights into the potential practical applications of a single material for dual gas sensing.

Femtosecond laser-textured superhydrophilic coral-like structures spread AgNWs enable strong thermal camouflage and anti-counterfeiting

Modulating the thermal emission of a material in the infrared (IR) range can be essential for various practical applications such as smart textiles, camouflage, and anti-counterfeiting. Although many different materials or structures have been proposed, the complex manufacturing processes are still hindering their widespread use. Herein, a facile femtosecond laser processing technology and a drop-coating method are introduced to form a patternable low emissivity film. Laser-treated polyimide films resulted in superhydrophilic structured surfaces that are uniformly coated with silver-nanowires (AgNWs) in aqueous solutions for low emissivity surfaces. Furthermore, the emissivity of the samples is as low as ∼0.2 without deterioration over 800 bending-releasing cycles. The as-prepared films also display good thermal camouflage properties, namely, the films reduced the thermal radiation temperature of an object by 35.8 °C when the object temperature was ∼69.1 °C. Additionally, this IR camouflage effect of the AgNWs coated samples shows excellent stability even in harsh environments such as immersion in water, acid, alkali, and salt solution and applied voltage. We also show that information encryption was possible by adjusting the amount of AgNWs. The design of this programmable patterned low emissivity film indicates an idea for the thermal camouflage and anti-counterfeiting technology, which can carry more abundant application scenario and disguise them more complex and sophisticated.

Ag nanofilm enhanced S-type Ag@AgCl/tubular g-C3N4/Ti photoanode visible light response photocatalytic fuel cell

In this study, based on Ag@AgCl/tubular g-C3N4 (Ag@AgCl/TCN) composite, Ag nanoparticles were deposited on its surface to form Ag nanofilm enhanced composite through photoreduction of excessive silver nitrate solution to obtain Ag nanofilm Ag@AgCl/TCN photocatalyst. Finally, Ag nanofilm Ag@AgCl/TCN/Ti photoanode was successfully prepared by silica-sol drop-coating method, and assembled with Cu2O/Cu cathode to construct a photocatalytic fuel cell (PFC). Ag nanofilm can not only enhance the light absorption and utilization of Ag@AgCl/TCN/Ti, but also extend its light response wavelength to visible light, and be used as an electron transfer medium to reduce internal resistance. The photocurrent density and the photoconversion efficiency of the Ag nanofilm/Ag@AgCl/TCN/Ti are 8.01 mA·cm−2 and 1.24%, respectively, which are 2.49 and 2.54 times those of the Ag@AgCl/TCN/Ti photoanode, respectively. The first-order kinetic constant and the maximum power density of the Ag nanofilm-coated Ag@AgCl/TCN/Ti-Cu2O/Cu PFC system are 0.064 min−1 and 46.37 μW·cm−2, respectively, which are 1.39 and 1.94 times those of the Ag@AgCl/TCN-Cu2O/Cu PFC system, respectively. In addition, it degraded more than 95% of rhodamine B, 72.68% of tetracycline and 54.25% of bisphenol A within 60 min. The excellent performance of Ag nanofilm/Ag@AgCl/TCN/Ti-Cu2O/Cu is due to the strengthening of Ag nanofilm and the formation of S-type heterojunctions between AgCl and TCN. Free radicals (•Cl, h+, •OH, •O2-) and non-radicals (1O2) are involved in the degradation reaction of RhB degradation. It is worth noting that 6% Ag nanofilm/Ag@AgCl/TCN/Ti-Cu2O/Cu has a positive effect on the production of •O2-, and its output is approximately 1.89 times that of the Ag@AgCl/TCN/Ti-Cu2O/Cu. A series of material characterization experiments have been completed and possible mechanisms of operation have been proposed. This study provides a new scheme for the design and preparation of high-efficiency photoanode of PFC.

BaTiO3/Fe2O3/MoS2/Ti photoanode for visible light responsive photocatalytic fuel cell degradation of rhodamine B and electricity generation

In order to improve the performance of visible light-responsive photocatalytic fuel cell (PFC), BaTiO3/Fe2O3/MoS2/Ti photoanode was prepared by a secondary hydrothermal and silica sol drop-coating method in this study, and assembled with Cu cathode to construct PFC. The composition, morphology, surface elements and chemical states, light absorption characteristics, rhodamine B degradation, electrochemical performance and stability of 10 % BaTiO3/Fe2O3/MoS2/Ti photoanode were studied. The rhodamine B degradation rate, maximum photocurrent density, and maximum power density of the PFC with 10 % BaTiO3/Fe2O3/MoS2/Ti photoanode are 94.23 %, 0.20 mA•cm−2 and 10.46 μW·cm−2, respectively. The excellent performance of the PFC is due to the internal electric field formed by the spontaneous polarization of the ferroelectric BaTiO3, which significantly promotes the charge transfer between MoS2 and Fe2O3, and realizes the spatial separation of photogenerated electrons and holes, thereby reducing the recombination of e−-h+ pairs and ultimately improving the photoelectricity and photocatalytic performance. This study provides an important reference for ferroelectric materials to promote the separation of photogenerated carriers in visible light responsive PFC.

A label-free photoelectrochemical biosensor for silver ions based on Zn-Co doped C and CdS QD nanomaterials.

A sensitive photoelectrochemical (PEC) biosensor for silver ions (Ag+) was developed based on Zn-Co doped C and CdS quantum dot (CdS QD) nanomaterials. Hydrophobic modified sodium alginate (HMA), which could stabilize and improve the PEC performance of CdS QDs, was also used for the construction of PEC sensors. Especially, Zn-Co doped C, CdS QDs and HMA were sequentially modified onto an electrode surface via the drop-coating method, and a C base rich DNA strand was then immobilized onto the modified electrode. As the C base in DNA specifically recognized Ag+, it formed a C-Ag+-C complex in the presence of Ag+, which created a spatial steric hindrance, resulting in a reduced PEC response. The sensing platform is sensitive to Ag+ in the range of 10.0 fM to 0.10 μM, with a limit of detection of 3.99 fM. This work offers an ideal platform to determine trace heavy metal ions in environmental monitoring and bioanalysis.

CoCr2O4/Graphene modified glass carbon electrode for highly dual-sensing detection of hydrogen peroxide and glucose

The development of a non-enzymatic electrochemical sensor possessing well dual-sensing to H2O2 and glucose remains challenging due to less report. Herein, spinel CoCr2O4 nanoparticles with small size were synthesized by sol–gel reaction, which were then simply mixed with commercial graphene under ultrasonic to obtain uniformly dispersed CoCr2O4/Graphene composite. They were deposited onto the surface of bare glassy carbon electrode (GCE) through a common drop-coating method. The CoCr2O4/Graphene/GCE sensor firstly achieves highly dual-sensing to H2O2 and glucose in 0.1 M NaOH solution. At 0.4 and 0.55 V, its sensitivities to H2O2 and glucose can separately reach up to 1168.6 and 1722.5 μA mM−1 cm−2, and the corresponding detection limits are as low as 18 nM and 12 nM. These key indexes are the best among reported dual-functional spinel oxide-based electrodes. This excellent electrochemical sensing ability stems from its large electrode active area, good conductivity, and the synergism between graphene and CoCr2O4 nanoparticles with mixed redox couplings, which provides an efficient platform for dual-sensing detection. In addition, the modified electrode can accurately determine glucose in human tears, rat serum and orange juice, as well as H2O2 in milk whey, mouthwash and disinfectant, thus predicting its good application prospects.

Preparation and Performance Study of Photoconductive Detector Based on Bi2O2Se Film

Bi2O2Se, as a novel two-dimensional semiconductor material, has been prepared and used in the field of photodetection. Herein, Bi2O2Se nanosheets were prepared using a hydrothermal method. Bi2O2Se films were also prepared using a drop-coating method. A photoconductive detector based on the Bi2O2Se film was constructed. The influence of nanosheet size was considered. Ultrasonic crashing treatments and different drying processes were used for the improvement of device performance. The obtained results demonstrate that the Bi2O2Se film based on treated nanosheets is denser and more continuous, leading to a higher photocurrent (1.4 nA). Drying in a vacuum can further increase the photocurrent of the device (3.0 nA). The photocurrent would increase with the increase in drying temperatures, while the dark current increases synchronously, leading to a decrease in the on/off ratio. The device based on Bi2O2Se film was dried in a vacuum at 180 °C and exhibited high responsivity (28 mA/W) and detectivity (~4 × 109 Jones) under 780 nm light illumination. Together, these results provide a data foundation and vision for the further development of photodetectors based on Bi2O2Se material.

Anthracene electrochemical sensor at fMWCNTs/ZnO modified glassy carbon electrode

The development of efficient and sensitive methods for polycyclic aromatic hydrocarbon (PAH) determination is necessitated by their potential environmental and health hazards. This study explores the application of glassy carbon electrode (GCE) modified with a nanocomposite of zinc oxide nanoparticles (ZnO NPs) reinforced functionalized multi-walled carbon nanotubes (fMWCNTs) as electrochemical sensor in the determination of anthracene. The functional, structural, and morphological properties of the nanomaterials were examined using techniques such as X-ray powder diffraction (XRD), Fourier-transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM), which validated the authenticity of the synthesis. Fabrication of the glassy carbon electrode was done utilizing the drop-coating method and the electrochemical properties probed in 10 mM [Fe(CN)6]3-/4- redox probe via electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). The nanocomposite-modified electrode, GCE/fMWCNTs/ZnO NPs recorded the highest anodic current response in the redox probe towering well above the other electrodes - bare GCE, GCE/ZnO NPs and GCE/fMWCNTs. The synergy between ZnO NPs and the fMWCNTs suggests accelerated transport of electrons between the ferrocyanide - ferricyanide redox probe and the modified electrode. Thereafter, the nanocomposite was explored for anthracene determination using CV and square wave voltammetry. With a similar performance in 0.4 μM anthracene, the GCE/fMWCNTs/ZnO NPs generated a higher cyclic voltammetry anodic current response of (459.05 μA), in contrast to the other electrodes - GCE/fMWCNTs (288.82 μA) GCE/ZnO NPs (19.67 μA), and the bare GCE (16.41 μA) at a scan rate of 25 mV/s, revealing very good electrocatalytic activity. A linear correlation (over a range of 9–75 µM) between the anodic current response and anthracene concentration yielded a micromole limit of detection of 1.27 µM. The proposed electrode was successfully used for the quantitation of anthracene in wastewater.

A Simple Strategy for the Simultaneous Determination of Dopamine, Uric Acid, L-Tryptophan and Theophylline Based on a Carbon Nano-Onions Modified Electrode

In this work, carbon nano-onions (CNOs) with particle sizes of 5–10 nm were prepared by the multi-potential step method. High-resolution transmission electron microscopy, infrared spectroscopy and Raman spectroscopy characterize the effective synthesis of CNOs. CNOs/GCEs were prepared by depositing the prepared CNOs onto glassy carbon electrodes (GCEs) by a drop-coating method. Examination of the electrocatalytic activity of the CNOs/GCE sensor by simultaneously detecting dopamine (DA), uric acid (UA), L-tryptophan (Trp) and theophylline (TP) using a differential pulse voltammetry technique. The results showed that the linear ranges of DA, UA, Trp and TP were DA 0.01–38.16 μM, UA 0.06–68.16 μM, Trp 1.00–108.25 μM, and TP 8.16–108.25 μM, and the detection limits (S/N = 3) were 0.0039 μM, 0.0087 μM, 0.18 μM and 0.35 μM, respectively. The CNOS/GCE sensor had good stability and could be used for the detection of actual samples.

An All-Fiber FLRD System for SO2 Detection Based on Graphene-Coated Microfiber

The accurate and effective detection of SF6 decomposition components inside a gas-insulated switchgear (GIS) is crucial for equipment fault diagnosis and condition assessment. The current method for detecting SF6 decomposition components involves gas extraction at the GIS inlet, which only provides limited information on the decomposition component content. Therefore, there is a need to explore more effective ways to obtain internal gas component information within GIS. In this study, we propose a graphene-coated microfiber gas detection method for SO2. We establish a physical simulation model of the microfiber and analyze the sensing mechanism of the microfiber diameter and cladding refractive index changes in its evanescent field. A graphene-coated microfiber gas sensor was prepared using a drop-coating method, and a fiber loop ring-down (FLRD) gas detection system was constructed for the experimental studies on SO2 gas detection. The results demonstrated that the graphene-coated microfiber exhibits an excellent gas-sensitive response to SO2 and achieves trace-level detection at room temperature. The concentration range of 0 to 200 ppm showed good linearity, with a maximum detection error of 4.76% and a sensitivity of 1.24 ns/ppm for SO2. This study introduces an all-fiber method for detecting SF6 decomposition components, offering a new approach for online monitoring of SF6 decomposition components in GIS equipment using built-in fiber-optic sensors.

In situ growth of Ag aerogels mediating effective electrocatalytic CO2 reduction and Zn-CO2 batteries

Metal aerogels have outshined themselves in electrocatalysis, however, the brittle property has constrained their intrinsic activity by the traditional drop-coating method of electrode preparation. Herein, a rapid in-situ growth strategy to obtain porous Ag aerogels on conductive carbon cloth (Ag As/CC) working as free-standing electrode was designed for electrocatalytic CO2 reduction to CO. The preserved porous network structure of Ag aerogels with hydrophobic surface effectively inhibits the competing reaction of hydrogen evolution. The CO Faraday efficiency of 99.6%, mass activityCO of 23.33 mA mg−1, and Energy efficiencyCO of 59.85% were achieved at −1.0 V vs. RHE. Ag As/CC exhibits quick charge response ability with relaxation time constant of 0.04 s, and high mass transfer with Tafel slope of 59 mV dec−1. It also worked as the cathode to drive Zn-CO2 rechargeable battery with a peak power density of 2.16mW cm−2, to achieve electrocatalytic CO2 fixation and energy storage.

Ag Nanoparticle-Thiolated Chitosan Composite Coating Reinforced by Ag-S Covalent Bonds with Excellent Electromagnetic Interference Shielding and Joule Heating Performances.

Conductive composite coatings are an important element in flexible electronics research and are widely used in energy transformation, artificial intelligence, and electronic skins. However, the comparatively low electrical conductivity limits their performance in many specific applications, such as electromagnetic interference (EMI) shielding and Joule heating devices. Therefore, the preparation of ultrahigh-electrical conductivity composite coatings with good flexibility and durability remains a great challenge. Herein, we fabricated multifunctional conductive composite coatings based on thiolated chitosan (TCS) and Ag nanoparticles (AgNPs) by an eco-friendly drop-coating method. The three-dimensional conductive network constructed by thermal sintering imparted the coating with an ultrahigh electrical conductivity of up to 67079.4 S/m. Moreover, the coating reinforced by Ag-S covalent bonding exhibits good stability, including heat resistance, chemical resistance, and mechanical stability. In addition, based on the ultrahigh electrical conductivity, the coating exhibits superior EMI shielding effectiveness and Joule heating capability. With 30 wt % of AgNPs in the coating, the EMI shielding effectiveness of the coating reaches 70.2 dB, far exceeding commercial standards. Additionally, the coating can quickly reach a saturation temperature (Ts) of 195.9 °C at a safe drive voltage of 3 V. These excellent performances demonstrate that the robust and flexible highly conductive composite coatings prepared by this method have attractive potential for EMI shielding and thermal management applications as well as in wearable electronics.

Study on Levodopa Sensor Modified by Ti3C2 MXene

The dosage management of levodopa is of great significance in the treatment of Parkinson’s disease. Measuring the patient’s levodopa concentration helps the physician to adjust the dose in time, so as to avoid complications. In this paper, we report an electrochemical sensor based on titanium carbide (Ti3C2) MXene nanomaterials, which can sensitively reflect the change of levodopa concentration. In the study, Ti3C2/GCE electrode was prepared by a simple drop-coating method, and then the Ti3C2/Pt/GCE electrode was prepared by modifying Pt nanoparticles on the electrode surface by impregnation adsorption method. After modification, the response of the GCE electrode to levodopa before and after Ti3C2 decoration was compared by cyclic voltammetry (CV), and the diffusion control process on the electrode surface was also investigated. Then, differential pulse voltammetry (DPV) was used to explore the relationship between the peak current of the oxidation anode and the concentration of levodopa. Finally, the relationship between current and concentration at a certain time point was explored by chronoamperometry (CA), and the time charge curves were plotted to explore the functional relationship between the amount of charge exchanged in the reaction and the concentration of levodopa (Coulomb analysis method). The research shows that the coulomb analysis method has a higher detection sensitivity and linear range, and this technology is expected to be applied to the in vivo monitoring of levodopa in our future research.

Enhanced Spectral Response of ZnO-Nanorod-Array-Based Ultraviolet Photodetectors by Alloying Non-Isovalent Cu-O with CuAlO2 P-Type Layer.

CuAlO2 was synthesized by a hydrothermal method, in which the Cu-O dimers were incorporated by simply altering the ratio of the reactants and the temperature. The incorporation process increases the grain size in CuAlO2, and modulates the work function and binding energies for CuAlO2 due to the partial substitution of Cu+ 3d10 with Cu2+ 3d9 orbitals in the valence band maximum by alloying non-isovalent Cu-O with a CuAlO2 host. Based on the ZnO nanorod arrays (NRs) ultraviolet photodetector, CuAlO2/Cu-O fabricated by the low-cost drop-coating method was used as the p-type hole transport layer. The incorporation of the Cu-O clusters into CuAlO2 lattice to enhance the conductivity of CuAlO2 is an effective way for improving ZnO NRs/CuAlO2 device performance. The photodetectors exhibit significant diode behavior, with a rectification ratio approaching 30 at ±1 V, and a dark saturation current density 0.81 mA cm-2. The responsivity of the ZnO-NRs-based UV photodetector increases from 13.2 to 91.3 mA/W at 0 V bias, with an increase in the detectivity from 2.35 × 1010 to 1.71 × 1011 Jones. Furthermore, the ZnO NRs/[CuAlO2/Cu-O] photodetector exhibits a maximum responsivity of 5002 mA/W at 1.5 V bias under 375 nm UV illumination.