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Keywords = Pd-decorated ZnO

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28 pages, 7293 KiB  
Article
Integration of p-Type PdPc and n-Type SnZnO into Hybrid Nanofibers Using Simple Chemical Route for Enhancement of Schottky Diode Efficiency
by A. Al-Sayed, Miad Ali Siddiq and Elsayed Elgazzar
Physics 2025, 7(1), 4; https://doi.org/10.3390/physics7010004 - 23 Jan 2025
Viewed by 2436
Abstract
Palladium phthalocyanine (PdPc) and palladium phthalocyanine integrated with tin–zinc oxide (PdPc:SnZnO) were prepared using a simple chemical approach, and their structural and morphological properties were identified using X-ray diffraction, energy dispersive X-ray analysis, scanning electron microscopy, and transmission electron microscopy techniques. The PdPc:SnZnO [...] Read more.
Palladium phthalocyanine (PdPc) and palladium phthalocyanine integrated with tin–zinc oxide (PdPc:SnZnO) were prepared using a simple chemical approach, and their structural and morphological properties were identified using X-ray diffraction, energy dispersive X-ray analysis, scanning electron microscopy, and transmission electron microscopy techniques. The PdPc:SnZnO nanohybrid revealed a polycrystalline structure combining n-type metal oxide SnZnO nanoparticles with p-type organic PdPc molecules. The surface morphology exhibited wrinkled nanofibers decorated with tiny spheres and had a large aspect ratio. The thin film revealed significant optical absorption within the ultraviolet and visible spectra, with narrow band gaps measured at 1.52 eV and 2.60 eV. The electronic characteristics of Al/n-Si/PdPc/Ag and Al/n-Si/PdPc:SnZnO/Ag Schottky diodes were investigated using the current–voltage dependence in both the dark conditions and under illumination. The photodiodes displayed non-ideal behavior with an ideality factor greater than unity. The hybrid diode showed considerably high rectification ratio of 899, quite a low potential barrier, substantial specific photodetectivity, and high enough quantum efficiency, found to be influenced by dopant atoms and the unique topological architecture of the nanohybrid. The capacitance/conductance–voltage dependence measurements revealed the influence of alternative current signals on trapped centers at the interface state, leading to an increase in charge carrier density. Full article
(This article belongs to the Section Applied Physics)
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16 pages, 4813 KiB  
Article
Enhancement of H2 Gas Sensing Using Pd Decoration on ZnO Nanoparticles
by Jin-Young Kim, Kyeonggon Choi, Seung-Wook Kim, Cheol-Woo Park, Sung-Il Kim, Ali Mirzaei, Jae-Hyoung Lee and Dae-Yong Jeong
Chemosensors 2024, 12(6), 90; https://doi.org/10.3390/chemosensors12060090 - 27 May 2024
Cited by 8 | Viewed by 1991
Abstract
Hydrogen (H2) gas, with its high calorimetric combustion energy and cleanness, is a green source of energy and an alternative to fossil fuels. However, it has a small kinetic diameter, with high diffusivity and a highly explosive nature. Hence, the reliable [...] Read more.
Hydrogen (H2) gas, with its high calorimetric combustion energy and cleanness, is a green source of energy and an alternative to fossil fuels. However, it has a small kinetic diameter, with high diffusivity and a highly explosive nature. Hence, the reliable detection of H2 gas is essential in various fields such as fuel cells. Herein, we decorated ZnO nanoparticles (NPs) with Pd noble metal NPs, using UV irradiation to enhance their H2 gas-sensing performance. The synthesized materials were fully characterized in terms of their phases, morphologies, and chemical composition. Then, the sensing layer was deposited on the electrode-patterned glass substrate to make a transparent sensor. The fabricated transparent gas sensor was able to detect H2 gas at various temperatures and humidity levels. At 250 °C, the sensor exhibited the highest response to H2 gas. As a novelty of the present study, we successfully detected H2 gas in mixtures of H2/benzene and H2/toluene gases. The enhanced H2 gas response was related to the catalytic effect of Pd, the formation of heterojunctions between Pd and ZnO, the partial reduction of ZnO to Zn in the presence of H2 gas, and the formation of PdHx. With a high performance in a high response, good selectivity, and repeatability, we believe that the sensor developed in this study can be a good candidate for practical applications where the detection of H2 is necessary. Full article
(This article belongs to the Special Issue Gas Sensors and Electronic Noses for the Real Condition Sensing)
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12 pages, 5719 KiB  
Article
Enhanced Acetone Sensing Properties Based on Au-Pd Decorated ZnO Nanorod Gas Sensor
by Yinfeng Shen, Yiping Liu, Chao Fan, Qudong Wang, Ming Li, Zhi Yang and Liming Gao
Sensors 2024, 24(7), 2110; https://doi.org/10.3390/s24072110 - 26 Mar 2024
Cited by 10 | Viewed by 2586
Abstract
The mature processes of metal oxide semiconductors (MOS) have attracted considerable interest. However, the low sensitivity of metal oxide semiconductor gas sensors is still challenging, and constrains its practical applications. Bimetallic nanoparticles are of interest owing to their excellent catalytic properties. This excellent [...] Read more.
The mature processes of metal oxide semiconductors (MOS) have attracted considerable interest. However, the low sensitivity of metal oxide semiconductor gas sensors is still challenging, and constrains its practical applications. Bimetallic nanoparticles are of interest owing to their excellent catalytic properties. This excellent feature of bimetallic nanoparticles can solve the problems existing in MOS gas sensors, such as the low response, high operating temperature and slow response time. To enhance acetone sensing performance, we successfully synthesized Au-Pd/ZnO nanorods. In this work, we discovered that Au-Pd nanoparticles modified on ZnO nanorods can remarkably enhance sensor response. The Au-Pd/ZnO gas sensor has long-term stability and an excellent response/recovery process. This excellent sensing performance is attributed to the synergistic catalytic effect of bimetallic AuPd nanoparticles. Moreover, the electronic and chemical sensitization of noble metals also makes a great contribution. This work presents a simple method for preparing Au-Pd/ZnO nanorods and provides a new solution for the detection of acetone based on metal oxide semiconductor. Full article
(This article belongs to the Section Environmental Sensing)
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10 pages, 3624 KiB  
Communication
Pd-Decorated ZnO Hexagonal Microdiscs for NH3 Sensor
by Yi Li, Boyu Zhang, Juan Li, Zaihua Duan, Yajie Yang, Zhen Yuan, Yadong Jiang and Huiling Tai
Chemosensors 2024, 12(3), 43; https://doi.org/10.3390/chemosensors12030043 - 5 Mar 2024
Cited by 58 | Viewed by 3554
Abstract
The NH3 sensor is of great significance in preventing NH3 leakage and ensuring life safety. In this work, the Pd-decorated ZnO hexagonal microdiscs are synthesized using hydrothermal and annealing processes, and the gas sensor is fabricated based on Pd-decorated ZnO hexagonal [...] Read more.
The NH3 sensor is of great significance in preventing NH3 leakage and ensuring life safety. In this work, the Pd-decorated ZnO hexagonal microdiscs are synthesized using hydrothermal and annealing processes, and the gas sensor is fabricated based on Pd-decorated ZnO hexagonal microdiscs. The gas-sensing test results show that the Pd-ZnO gas sensor has a good response to NH3 gas. Specifically, it has a good linear response within 0.5–50 ppm NH3 at the optimal operating temperature of 230 °C. In addition, the Pd-ZnO gas sensor exhibits good repeatability, short response time (23.2 s) and good humidity resistance (10–90% relative humidity). This work provides a useful reference for developing an NH3 sensor. Full article
(This article belongs to the Special Issue The State-of-the-Art Gas Sensor)
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14 pages, 3218 KiB  
Article
Pain-Free Alpha-Synuclein Detection by Low-Cost Hierarchical Nanowire Based Electrode
by Gisella M. Di Mari, Mario Scuderi, Giuseppe Lanza, Maria Grazia Salluzzo, Michele Salemi, Filippo Caraci, Elena Bruno, Vincenzina Strano, Salvo Mirabella and Antonino Scandurra
Nanomaterials 2024, 14(2), 170; https://doi.org/10.3390/nano14020170 - 12 Jan 2024
Cited by 17 | Viewed by 2575
Abstract
Analytical methods for the early detection of the neurodegenerative biomarker for Parkinson’s disease (PD), α-synuclein, are time-consuming and invasive, and require skilled personnel and sophisticated and expensive equipment. Thus, a pain-free, prompt and simple α-synuclein biosensor for detection in plasma is highly demanded. [...] Read more.
Analytical methods for the early detection of the neurodegenerative biomarker for Parkinson’s disease (PD), α-synuclein, are time-consuming and invasive, and require skilled personnel and sophisticated and expensive equipment. Thus, a pain-free, prompt and simple α-synuclein biosensor for detection in plasma is highly demanded. In this paper, an α-synuclein electrochemical biosensor based on hierarchical polyglutamic acid/ZnO nanowires decorated by gold nanoparticles, assembled as nanostars (NSs), for the determination of α-synuclein in human plasma is proposed. ZnO NSs were prepared by chemical bath deposition (CBD) and decorated with electrodeposited Au nanoparticles (Au NPs). Then, electro-polymerized glutamic acid was grown and functionalized with anti-α-synuclein. A synergistic enhancement of electrode sensitivity was observed when Au NPs were embedded into ZnO NSs. The analytical performance of the biosensor was evaluated by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), using the Fe(II)(CN)64−/Fe(III)(CN)63− probe. The charge transfer resistance after α-synuclein recognition was found to be linear, with a concentration in the range of 0.5 pg·mL−1 to 10 pg·mL−1, a limit of detection of 0.08 pg·mL−1, and good reproducibility (5% variation) and stability (90%). The biosensor was also shown to reliably discriminate between healthy plasma and PD plasma. These results suggest that the proposed biosensor provides a rapid, quantitative and high-sensitivity result of the α-synuclein content in plasma, and represents a feasible tool capable of accelerating the early and non-invasive identification of Parkinson’s disease. Full article
(This article belongs to the Section Nanoelectronics, Nanosensors and Devices)
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19 pages, 5003 KiB  
Article
Surface-Catalyzed Zinc Oxide Nanorods and Interconnected Tetrapods as Efficient Methane Gas Sensing Platforms
by Abbey Knoepfel, Bed Poudel and Sanju Gupta
Chemosensors 2023, 11(9), 506; https://doi.org/10.3390/chemosensors11090506 - 17 Sep 2023
Cited by 3 | Viewed by 2122
Abstract
Nanostructured metal oxide semiconductors have proven to be promising for the gas sensing domain. However, there are challenges associated with the fabrication of high-performance, low-to-room-temperature operation sensors for methane and other gases, including hydrogen sulfide, carbon dioxide, and ammonia. The functional properties of [...] Read more.
Nanostructured metal oxide semiconductors have proven to be promising for the gas sensing domain. However, there are challenges associated with the fabrication of high-performance, low-to-room-temperature operation sensors for methane and other gases, including hydrogen sulfide, carbon dioxide, and ammonia. The functional properties of these semiconducting oxides can be improved by altering the morphology, crystal size, shape, and topology. Zinc oxide (ZnO) is an attractive option for gas sensing, but the need for elevated operating temperatures has limited its practical use as a commercial gas sensor. In this work, we prepared ZnO nanorod (ZnO-NR) arrays and interconnected tetrapod ZnO (T-ZnO) network sensing platforms as chemiresistive methane sensors on silicon substrates with platinum interdigitated electrodes and systematically characterized their methane sensing response in addition to their structural and physical properties. We also conducted surface modification by photochemical-catalyzed palladium, Pd, and Pd-Ag alloy nanoparticles and compared the uniformly distributed Pd decoration versus arrayed dots. The sensing performance was assessed in terms of target gas response magnitude (RM) and response percentage (R) recorded by changes in electrical resistance upon exposure to varying methane concentration (100–10,000 ppm) under thermal (operating temperatures = 175, 200, 230 °C) and optical (UV A, 365 nm illumination) excitations alongside response/recovery times, and limit of detection quantification. Thin film sensing platforms based on T-ZnO exhibited the highest response at 200 °C (RM = 2.98; R = 66.4%) compared to ZnO-NR thin films at 230 °C (RM = 1.34; R = 25.5%), attributed to the interconnected network and effective bandgap and barrier height reduction of the T-ZnO. The Pd-Ag-catalyzed and Pd dot-catalyzed T-ZnO films had the fastest response and recovery rates at 200 °C and room temperature under UV excitation, due to the localized Pd nanoparticles dots resulting in nano Schottky barrier formation, as opposed to the films coated with uniformly distributed Pd nanoparticles. The experimental findings present morphological differences, identify various mechanistic aspects, and discern chemical pathways for methane sensing. Full article
(This article belongs to the Special Issue The State-of-the-Art Gas Sensor)
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13 pages, 4324 KiB  
Article
Highly Sensitive Ethylene Sensors Based on Ultrafine Pd Nanoparticles-Decorated Porous ZnO Nanosheets and Their Application in Fruit Ripeness Detection
by Zhen Jin, De-Cai Wang, Wen-Jie Xie, Yi Ding and Jie Li
Processes 2023, 11(6), 1686; https://doi.org/10.3390/pr11061686 - 1 Jun 2023
Cited by 6 | Viewed by 2362
Abstract
Ethylene is the most common ripening phytohormone in fruits, and excess ethylene can overripen the fruit. However, the in-field detection of ethylene is still limited. In this work, ultrafine Pd nanoparticles-decorated porous ZnO nanosheets (UPNP ZnO nanosheets) were conveniently synthesized through a facile [...] Read more.
Ethylene is the most common ripening phytohormone in fruits, and excess ethylene can overripen the fruit. However, the in-field detection of ethylene is still limited. In this work, ultrafine Pd nanoparticles-decorated porous ZnO nanosheets (UPNP ZnO nanosheets) were conveniently synthesized through a facile solvent reduction method. The UPNP ZnO nanosheets were characterized using scanning electron microscopy, transmission electron microscopy, energy dispersive spectrum, X-ray diffraction and X-ray photoelectron spectroscopy. The ZnO nanosheets were uniformly coated with Pd nanoparticles. The size of the Pd nanoparticle was very small, with a diameter of approximately 2 nm. Due to the unique structure of the porous ZnO nanosheets and the excellent catalytic properties of the ultrafine Pd nanoparticles, the as-prepared samples showed very high sensing performance in ethylene detection. The lowest detection concentration was 10 ppb, which is the lowest detection limit to our knowledge. It has been proved that the decoration of ultrafine Pd nanoparticles can largely increase the relative percentage of chemisorbed oxygen and deficient oxygen, which are benefits for ethylene oxidation, and actually accelerate the process of the sensing reaction. Furthermore, the UPNP ZnO nanosheets can even be applied in fruit maturity detection. Using mangos as an example, our experiment revealed that the response of UPNP ZnO nanosheets to mangos at different maturity stages was quite different. This result suggests that our product has broad application prospects in monitoring fruit ripening stage. Full article
(This article belongs to the Special Issue Controllable Preparation and Application of Metal Compounds)
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20 pages, 6722 KiB  
Article
Optimal Icosahedral Copper-Based Bimetallic Clusters for the Selective Electrocatalytic CO2 Conversion to One Carbon Products
by Azeem Ghulam Nabi, Aman-ur-Rehman, Akhtar Hussain, Gregory A. Chass and Devis Di Tommaso
Nanomaterials 2023, 13(1), 87; https://doi.org/10.3390/nano13010087 - 24 Dec 2022
Cited by 10 | Viewed by 3611
Abstract
Electrochemical CO2 reduction reactions can lead to high value-added chemical and materials production while helping decrease anthropogenic CO2 emissions. Copper metal clusters can reduce CO2 to more than thirty different hydrocarbons and oxygenates yet they lack the required selectivity. We [...] Read more.
Electrochemical CO2 reduction reactions can lead to high value-added chemical and materials production while helping decrease anthropogenic CO2 emissions. Copper metal clusters can reduce CO2 to more than thirty different hydrocarbons and oxygenates yet they lack the required selectivity. We present a computational characterization of the role of nano-structuring and alloying in Cu-based catalysts on the activity and selectivity of CO2 reduction to generate the following one-carbon products: carbon monoxide (CO), formic acid (HCOOH), formaldehyde (H2C=O), methanol (CH3OH) and methane (CH4). The structures and energetics were determined for the adsorption, activation, and conversion of CO2 on monometallic and bimetallic (decorated and core@shell) 55-atom Cu-based clusters. The dopant metals considered were Ag, Cd, Pd, Pt, and Zn, located at different coordination sites. The relative binding strength of the intermediates were used to identify the optimal catalyst for the selective CO2 conversion to one-carbon products. It was discovered that single atom Cd or Zn doping is optimal for the conversion of CO2 to CO. The core@shell models with Ag, Pd and Pt provided higher selectivity for formic acid and formaldehyde. The Cu-Pt and Cu-Pd showed lowest overpotential for methane formation. Full article
(This article belongs to the Special Issue Nanocatalysts for Methanation Reaction)
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14 pages, 6233 KiB  
Article
Self-Powered Nitrogen Dioxide Sensor Based on Pd-Decorated ZnO/MoSe2 Nanocomposite Driven by Triboelectric Nanogenerator
by Weiwei Wang, Dongyue Wang, Xixi Zhang, Chunqing Yang and Dongzhi Zhang
Nanomaterials 2022, 12(23), 4274; https://doi.org/10.3390/nano12234274 - 1 Dec 2022
Cited by 15 | Viewed by 2538
Abstract
This paper introduces a high-performance self-powered nitrogen dioxide gas sensor based on Pd-modified ZnO/MoSe2 nanocomposites. Poly(vinyl alcohol) (PVA) nanofibers were prepared by high-voltage electrospinning and tribological nanogenerators (TENGs) were designed. The output voltage of TENG and the performance of the generator at [...] Read more.
This paper introduces a high-performance self-powered nitrogen dioxide gas sensor based on Pd-modified ZnO/MoSe2 nanocomposites. Poly(vinyl alcohol) (PVA) nanofibers were prepared by high-voltage electrospinning and tribological nanogenerators (TENGs) were designed. The output voltage of TENG and the performance of the generator at different frequencies were measured. The absolute value of the maximum positive and negative voltage exceeds 200 V. Then, the output voltage of a single ZnO thin-film sensor, Pd@ZnO thin-film sensor and Pd@ZnO/MoSe2 thin-film sensor was tested by using the energy generated by TENG at 5 Hz, when the thin-film sensor was exposed to 1–50 ppm NO2 gas. The experimental results showed that the sensing response of the Pd@ZnO/MoSe2 thin-film sensor was higher than that of the single ZnO film sensor and Pd@ZnO thin-film sensor. The TENG-driven response rate of the Pd@ZnO/MoSe2 sensor on exposure to 50 ppm NO2 gas was 13.8. At the same time, the sensor had good repeatability and selectivity. The synthetic Pd@ZnO/MoSe2 ternary nanocomposite was an ideal material for the NO2 sensor, with excellent structure and performance. Full article
(This article belongs to the Special Issue Advanced Nanomaterials and Nanotechnologies for Micro/Nano-Sensors)
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14 pages, 6864 KiB  
Article
Defective ZnO Nanoflowers Decorated by Ultra-Fine Pd Clusters for Low-Concentration CH4 Sensing: Controllable Preparation and Sensing Mechanism Analysis
by Yang Chen, Wenshuang Zhang, Na Luo, Wei Wang and Jiaqiang Xu
Coatings 2022, 12(5), 677; https://doi.org/10.3390/coatings12050677 - 15 May 2022
Cited by 6 | Viewed by 2245
Abstract
To detect low concentration of CH4 is indeed meaningful in industrial manufacturing, such as the petrochemical industry and natural gas catalysis, but it is not easy to detect low concentration of CH4 due to its high symmetrical and stable structure. In [...] Read more.
To detect low concentration of CH4 is indeed meaningful in industrial manufacturing, such as the petrochemical industry and natural gas catalysis, but it is not easy to detect low concentration of CH4 due to its high symmetrical and stable structure. In this work, defect-rich ZnO1−x nanoflowers (NFs) were synthesized by a two-step route so as to obtain defect-enhanced gas-sensing performance, namely hydrothermal synthesis followed by H2 treatment. In order to achieve low-concentration detection of CH4, the ultra-thin Pd clusters’ (Cs, diameter about 1–2 nm) sensitizer was synthesized and decorated onto the surface of ZnO1−x NFs. It is found that Pd Cs-2/ZnO1−x gas sensors show enhanced gas-sensing properties to CH4, even at ppm concentration level. At its optimal working temperature of 260 °C, the gas response to 50 ppm CH4 can reach 5.0 with good gas selectivity; the response and recovery time is only 16.2 and 13.8 s, respectively. In the Results, we discussed the CH4 gas-sensing mechanism deeply. Overall, it is very necessary to detect low-concentration methane safely. It is possible for further safe detection of low-concentration methane gas in the future. Full article
(This article belongs to the Special Issue Surface Modified Nanoparticles: For Gas and Chemical Sensors)
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10 pages, 3078 KiB  
Article
Influences of Work Function Changes in NO2 and H2S Adsorption on Pd-Doped ZnGa2O4(111) Thin Films: First-Principles Studies
by Jen-Chuan Tung, Ding-Yuan Wang, Yu-Hsuan Chen and Po-Liang Liu
Appl. Sci. 2021, 11(11), 5259; https://doi.org/10.3390/app11115259 - 5 Jun 2021
Cited by 9 | Viewed by 2887
Abstract
The work function variations of NO2 and H2S molecules on Pd-adsorbed ZnGa2O4(111) were calculated using first-principle calculations. For the bonding of a nitrogen atom from a single NO2 molecule to a Pd atom, the maximum [...] Read more.
The work function variations of NO2 and H2S molecules on Pd-adsorbed ZnGa2O4(111) were calculated using first-principle calculations. For the bonding of a nitrogen atom from a single NO2 molecule to a Pd atom, the maximum work function change was +1.37 eV, and for the bonding of two NO2 molecules to a Pd atom, the maximum work function change was +2.37 eV. For H2S adsorption, the maximum work function change was reduced from −0.90 eV to −1.82 eV for bonding sulfur atoms from a single and two H2S molecules to a Pd atom, respectively. Thus, for both NO2 and H2S, the work function change increased with an increase in gas concentration, showing that Pd-decorated ZnGa2O4(111) is a suitable material in NO2/H2S gas detectors. Full article
(This article belongs to the Special Issue Selected Papers from ISET 2020 and ISPE 2020)
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