Zinc Oxide Surface Research Articles

Investigating the Antibacterial Properties of ZnO-NPs

The size range of several hundred nanometers to several of micrometers contains a lot of microorganisms. The aim of the current report was to study the antibacterial properties of ZnO-NPs through a theoretical review of the most important findings in previous studies. The study found the most important antibacterial properties of ZnO-NPs, including: Strong antibacterial results can be achieved by enhancing variables such as UV light, zinc oxide particle size, concentration, shape, and surface modification, which affect many different toxicological processes. One of the main properties of ZnO-NPs is the production of intracellular ROS formation, as well as the mechanical damage of the cell wall due to the release of Zn2+ ion and its attachment to the cell membrane.

Selective detection of ammonia by rGO decorated nanostructured ZnO for poultry and farm field applications

Nanostructured Zinc Oxide (ZnO) was deposited by the spray pyrolysis technique. The ZnO was further functionalized by reduced Graphene Oxide (rGO) using the doctor blade method. The X-ray Diffraction (XRD) studies of bare and rGO functionalized ZnO showed multiple peaks and polycrystalline in nature. The morphological studies confirmed rGO distribution over the ZnO surface. The ammonia sensing studies of the bare and functionalized ZnO were analyzed by varying the temperature from room temperature (RT) to 450 °C. The rGO/ZnO exhibited increased sensitivity towards ammonia at a lower temperature (300 °C) compared with bare ZnO. The range of detection was found to be 0.5 ppm to 100 ppm. The selectivity studies towards 20 ppm ammonia in a mixed gas environment were also investigated.

Self-aligned liquid crystals and enhanced electro-optical properties on solution-processed aluminum gallium tin zinc oxide surfaces

An aluminum gallium tin zinc oxide (AlGaSnZnO) film was fabricated by brush coating to create a directional micro/nano structure. Atomic force microscopy was used to observe the physical change in the film surface after brush coating, and the difference in the surface modification according to the curing temperature was analyzed through line profile and surface roughness studies. Changes in the chemical composition of the surface were analyzed through X-ray photoelectron spectroscopy. The liquid crystal (LC) alignment characteristics were analyzed through polarized optical microscopy, pretilt angle, and thermal stability tests. It was confirmed that the orientation direction of LC molecules changed from vertical to horizontal due to the difference in the surface modification at a curing temperature of 180 °C or higher, and stable LC orientation and excellent electro-optical properties were achieved. Brush-coated AlGaSnZnO film is an effective alignment film that controls the LC alignment characteristics with a simple process and can be applied in various fields.

The pH dependence of dissolution kinetics of zinc oxide

Zinc oxide (ZnO) powders are used as feed additives for supplementation in diet of animals. Because zinc dissolution rate strongly influences the digestibility of zinc by animals and their stomach has variable pH, the dissolution kinetics of ZnO are studied at the several pH of relevance between 2 and 4. The dissolution of ZnO has been investigated with the help of modeling the dissolution kinetics measured in vitro at various pH. Dissolution is faster in acidic medium. But the acceleration of dissolution at low pH is moderate compared to what would be expected on the basis of the strong pH dependence of ZnO solubility. The concentration of Zn2+ in the quiescent medium at the surface of ZnO particles is much lower than its solubility. It is proposed as a rationale, that hydroxide anions released during dissolution accumulate at the surface of the positively charged ZnO surface, and that the dissolution kinetics is mainly controlled by the diffusion of H+ ions from the bulk solution to the surface.

Sensing Characteristics of ZnO Nanoparticle Film towards Acetone

Over the past few decades, nanomaterials of metal oxide such as zinc oxide (ZnO) have been significantly researched for sensing various toxic gases like ethanol, acetone and ammonia. The sensing performance of semiconducting materials depends primarily on their surface structure and the interaction behavior with target gas molecules. The surface quality of ZnO is highly influenced by deposition methods. Although several ZnO surfaces have been rigorously studied for detecting gas leakages, it still possesses drawbacks such as high operating temperature, slow response and recovery times. Henceforth, this investigation was carried out to resolve these issues in the fabrication of future ZnO-based gas sensors. In this work, we report the major findings of the ZnO-based nanoparticle film gas sensor prepared by a doctor blade method to gain insight towards detecting various concentrations of acetone gas at different temperatures. The XRD and FTIR results confirmed the phase purity of ZnO. The results showed the highest response ratio of 25.697 0.012 at 285 oC with an exposure of 800 ppm of acetone along with the quick response and recovery times of 39 sec and 79 sec, respectively. This operating temperature was found to be lower than the reported value for a similar system than that prepared via different methods.

One-step fabrication of self-cleaning superhydrophobic surfaces: A combined experimental and molecular dynamics study

A simple one-step approach was developed to fabricate self-cleaning superhydrophobic surfaces by soaking the copper substrates into a mixed solution containing zinc oxide, stearic acid and polyphenylene sulfide molecules. X-ray photoelectron spectra confirmed that the hybridization between organic polymers and inorganic molecules happened. Further scanning electron microscopy analyses revealed that hierarchical structure was formed. A synergy between modified surface chemistry and surface roughness provided copper substrates with superhydrophobic properties and good self-cleaning performance. The fabricated superhydrophobic surfaces exhibited a water contact angle as high as ∼164.7 ± 1.5° and a sliding angle as low as ∼4.0 ± 0.8°. Molecular dynamics simulations were applied to study the adsorption behavior of stearic acid molecules on the zinc oxide crystal surfaces and the wettability of water molecules on as-prepared surfaces at molecular level. Molecular dynamics simulation results illustrated that the hydrophilic interactions between water droplets and zinc oxide surfaces involved hydrogen-bond formation, whereas the hydrophobic interaction between water molecules and superhydrophobic surfaces involved Van der Waals's interaction between the alkyl chains.

Morphological and chemical evolution of transient interfaces during zinc oxide cold sintering process

Although zinc oxide has a high melting point of 1975 °C, the recent development of the cold sintering process has shown that highly dense polycrystalline ceramics can be obtained at 150 °C or below. As such unusual densification does not yet have fully elucidated underlying mechanisms, this study aims to provide a comprehensive investigation of transient morphological and chemical interfaces during isothermal dwell. The chemical “transient” interface involves the formation of a zinc carboxylate complex by reacting the host zinc oxide powder and acetic acid solution, which is later consumed for the recrystallization on the lattice of an adjacent grain with a decomposition of the complex. Hence, the final outcome can be a residual-free zinc oxide phase. Regarding the morphological evolution, gas physisorption studies were conducted to quantify the area of solid–vapor interfaces and the Schlaffer model was used to analyze the activation energy for specific surface area reduction. Moreover, transmission electron micrographs revealed that the recrystallization occurs at the interface between crystalline grain and carbon-rich amorphous phase. After 30 minutes of isothermal dwell, the area of the amorphous phase was significantly decreased while grain size was increased, potentially indicating the recrystallization-induced grain growth and pore closure. The chemical transition at the zinc oxide surface was further investigated using ReaxFF molecular dynamics simulation, observing that acetate molecule acts as a bridging complex to connect zinc ions to the surface. Overall, understanding the evolution of the transient interface is a crucial subject to obtaining a residual-free cold-sintered sample with desired grain size and properties for application developments.

Effect of proton irradiation temperature on persistent photoconductivity in zinc oxide metal-semiconductor-metal ultraviolet photodetectors

The electrical and structural characteristics of 50-nm-thick zinc oxide (ZnO) metal-semiconductor-metal ultraviolet (UV) photodetectors subjected to proton irradiation at different temperatures are reported and compared. The devices were irradiated with 200 keV protons to a fluence of 1016 cm−2. Examination of the x-ray diffraction (XRD) rocking curves indicates a preferred (100) orientation prior to irradiation, with decrease in crystal quality afterward. Additionally, peak shifts in XRD and Raman spectra of the control sample relative to well-known theoretical positions are indicative of tensile strain in the as-deposited ZnO films. Shifts toward theoretical unstrained positions are observed in the irradiated films, which indicates partial relaxation. Raman spectra also indicate increase in oxygen vacancies (VO) and zinc interstitial defects (Zni) compared to the control sample. Additionally, transient photocurrent measurements performed on each sample at different temperatures showed up to 2× increase in photocurrent decay time constants for irradiated samples vs the control. This persistent photoconductive behavior is linked to the activation of electron and hole traps near the surface, and to the desorption and reabsorption of O2 molecules on the ZnO surface under the influence of UV light. Using an Arrhenius model, trap activation energies were extracted and, by comparing with known energies from the literature, the dominant defects contributing to persistent photoconductivity for each irradiation condition were identified. The persistence of differences in photocurrent transients between different samples months after irradiation indicates that the defects introduced by the suppression of thermally activated dynamic annealing processes have a long-term deleterious effect on device performance.

Using MgO capping layer to enhance the performance of ZnO based metal-semiconductor-metal photodetectors

Magnesium oxide (MgO) was deposited on zinc oxide (ZnO) surface to achieve a visible-blind ultraviolet (UV) metal-semiconductor-metal photodetectors (MSM-PDs). ZnO and MgO were prepared using a radio-frequency (RF) magnetron sputtering system. As compared to the MSM-PDs without the MgO capping layer, the dark current is greatly subdued by approximately four orders of magnitude in the MSM-PDs with MgO capping layer, which in turn largely increases the photo/dark current ratio from 102 to 105 by three orders in the MSM-PDs. The MgO capping layer enhances the ultraviolet/visible rejection ratio and largely raised the detectivity from 8.3 × 1010 to 1.03 × 1012 Jones in the prepared MSM-PDs. X-ray photoelectron spectroscopy shows that the oxygen vacancies on ZnO surface were compensated by the introduced oxygen atoms from MgO, forming a stable film that passivated the ZnO surface. The MgO capping layer greatly increases the Schottky barrier height (SBH) of an Au/ZnO Schottky barrier diode (SBD) from 0.58 to 0.93 eV for the Au/MgO/ZnO SBD. The raised SBH and suppressed surface defects drastically reduced the dark current and visible response of the prepared MSM-PDs.

Revealing a Zinc Oxide/Perovskite Luminescence Quenching Mechanism Targeting Low-Roll-off Light-Emitting Diodes.

Balanced charge injection is key to achieving perovskite light-emitting diodes (PeLEDs) with a low efficiency roll-off at a high brightness. The use of zinc oxide (ZnO) with a high electron mobility as the charge transport layers is desirable; however, photoluminescence (PL) quenching of a perovskite on ZnO always occurs. Here, a quasi-two-dimensional perovskite on ZnO is explored to uncover the PL quenching mechanism, mainly ascribed to the deprotonation of ammonium cations on the ZnO film in association with the decomposition of low-dimensional perovskite phases. Surprisingly, crystal plane-dependent PL quenching results indicate that the deprotonation rate strongly correlates with the crystal orientation of the ZnO surface. We developed a strategy for suppressing perovskite PL quenching by incorporating an atomic layer deposited Al2O3 onto the ZnO film. Consequently, an efficient inverted PeLED was achieved with a maximum external quantum efficiency of 17.7% and a less discernible efficiency roll-off at a high current density.

Investigation of morphology, crystal structure and property of ZnO/poly (methylstyrene-co-chloromethyl styrene) nanocomposite

A nanocomposite composed of ZnO and poly (methyl styrene-co-chloro methyl styrene) P (MSt-co-CMSt) by in situ polymerization method were prepared successfully. For this purpose, firstly, the zinc oxide surface was treated with 3-(trimethoxysilyl) propyl methacrylate (TMSPMA), a silane coupling agent, and following that this functionalization nano-ZnO particle was reacted with PMSt to prepare PMSt-grafted TMSPMA-ZnO. The resulting PMSt-grafted TMSPMA-ZnO was brominated with N-bromosuccinimide and coupled with 1-hydroxy-2, 2, 6, 6-tetramethyl-1-piperidinyloxy (TEMPO-OH) to produce an NMRP macroinitiator (PMSt-TEMPO/nano-ZnO). The well-controlled graft polymerization of 4-chloromethyl styrene (CMSt) with macroinitiators were carried out to produce nanoparticles based-ZnO (PMSt-co-PCMSt)/zinc oxide nanocomposite). Properties, crystal structure, and the morphology of (PMSt-co-PCMSt)/zinc oxide nanocomposite was studied using 1H-NMR, FT-IR, XRD, TGA, DSC, TEM, and UV-Vis spectroscopy. The results of FT-IR investigation and observations of TEM images represented clear and strong evidence for the preparation of PMSt and PMSt-co-PCMSt with spherical morphology of ZnO nanoparticles. The synthesized nanocomposites can be utilized a compound to attenuate the UV irradiation in the range of pointed wavelength.

Sustainable Synthesis of Ionic Liquid-Functionalized Zinc Oxide Nanosheets (IL@ZnO): Evaluation of Antibacterial Potential Activity for Biomedical Applications.

Zinc oxide (ZnO)-derived materials exhibit unique antibacterial, antifungal, and photochemical activities and are widely used in antibacterial formulations. In this work, ZnO nanosheets were prepared by green and cost-effective synthesis via a hydrothermal method, and the prepared ZnO nanosheets were further functionalized with an eco-friendly ionic liquid (IL). Thus, a sustainable approach was established to synthesize ZnO nanosheets. The functionalization of ZnO with the synthesized IL was fully characterized by advanced spectroscopic and microscopic techniques. The prepared ionic liquid-functionalized ZnO (IL@ZnO) showed self-organized layered-sheet arrangements caused by the intercalation of the IL onto the surface of ZnO nanosheets as revealed by scanning electron microscopy (SEM). The design of the IL comprised a carboxylic acid moiety for functionalization onto the surface of ZnO, whereas the hydrophobicity was tuned through the incorporation of a long alkyl chain. The developed IL@ZnO material was also tested against both Gram-positive and Gram-negative pathogenic bacteria for potential antibacterial activity by colony-forming unit (CFU) and minimum inhibitory concentration tests. The results revealed that the IL@ZnO exhibits significant antibacterial activity against tested strains. In particular, potent activity was observed against the Gram-positive skin-specific Staphylococcus aureus bacteria strain. The mechanism of bactericidal activity against bacteria was also explored along with the cytotoxicity toward mammalian cells, which reveals that the IL@ZnO is nontoxic in nature. To utilize the developed material owing to its bactericidal activity for practical applications, the IL@ZnO was fabricated onto the surface of cotton fabric, and its surface morphology was examined by SEM; the activity of IL@ZnO-treated cotton fabric was evaluated by the zone of inhibition assay. Additionally, the IL@ZnO-treated cotton fabric exhibited remarkable stability along with significant hydrophobicity and breathability and thus can be utilized as a biomaterial for biomedical applications, especially in medical masks, for reducing the risk of transmission of infectious diseases.

Improved anti-inflammatory and anticancer properties of celecoxib loaded zinc oxide and magnesium oxide nanoclusters: A molecular docking and density functional theory simulation

Present study offers great prospects for the adsorption of anti-inflammatory celecoxib molecule (CXB) over the surface of zinc oxide (Zn12O12) and magnesium oxide (Mg12O12) nanoclusters in several environments by performing robust theoretical calculations. Density functional theory (DFT), time-dependent density functional theory (TDDFT) and molecular docking calculations have been extensively carried out to predict the foremost optimum site of CXB adsorption. It has been observed that the CXB molecule prefers to be adsorbed by its SO2 site on the Zn-O and Mg-O bonds of the Zn12O12 and Mg12O12 nanoclusters instead of NH2 and NH sites, where electrostatic interactions dominate over the bonding characteristics of the conjugate complexes. Furthermore, the presence of interactions between the CXB molecule and nanoclusters has also been evidenced by the UV–Vis absorption spectra and IR spectra. Molecular docking analysis has revealed that both adsorption states including CXB/Zn12O12 and CXB/Mg12O12 have good inhibitory potential against protein tumor necrosis factor alpha (TNF-α) and Interleukin-1 (IL-1), and human epidermal growth factor receptor 2 (HER2). Hence they might be explored as efficient TNF-α, IL-1, and HER2 inhibitors. Hence from the study, it can be anticipated that these nanoclusters can behave as an appropriate biomedical carrier for the CXB drug delivery.

Electron localization of ZnO/Znln2S4 interface induced lattice relaxation for triggering photocatalytic uranium evolution

Designing a material that efficiently extracts uranium (U) from natural seawater and resists biofouling remains a critical challenge. Here, flake Znln2S4 grew in situ on the surface of black porous zinc oxide (B-ZnO), and finally a binary composite material (B-ZnO/ZnIn2S4) is synthesized. Based on the reduction process of U(VI), the chemical reaction of the U(VI) → U(IV) process occurred on the surface and interface of the composite material. The S-scheme heterojunction system constructed of ZnO and Znln2S4 with a matching band structure showed great potential for promoting the separation and transfer of photogenerated carriers and obtaining powerful photoredox capabilities. By generating biologically toxic free radical reactive oxygen species and Zn2+, the adsorbent had high antibiological fouling activity. After 120 min of extraction in simulated seawater, the light-induced reduction ability of B-ZnO/ZnIn2S4-45% (mass ratio) on U(VI) reached 99%, which was 6.2 times higher than that under dark conditions. The conversion path of U(VI) was calculated by density functional theory (DFT). In addition, ZnIn2S4 (007) exhibited the ability to localize to the surface of ZnO (002) and promote electron transfer. These results indicate that interface atomic structure engineering is crucial for the synthesis of efficient and durable seawater U(VI) extraction catalysts.

Environmentally friendly ZnO/Castor oil polyurethane composites for the gas-phase adsorption of acetic acid

HypothesisAcetic acid, a common pollutant present in museums and art galleries, can irreversibly damage works of art. Herein, a sustainable and scalable synthesis of zinc oxide-castor oil polyurethane hybrids (ZnO/COPs), to be used as acetic acid removers in the preventive conservation of Cultural Heritage, is reported. ExperimentsThe adsorption capacities of ZnO/COPs were studied in saturated acetic acid atmosphere, at low acetic acid gas concentration, and inside a wooden crate (naturally emitting acetic acid) representative of those used in the storage deposits of museums and art collections. FindingsUpon exposure, acetic acid interacts with the castor oil polyurethane and diffuses to the surface of ZnO particles where is stably fixed as zinc acetate crystals. Zinc acetate domains form homogeneously on the surface and are distributed evenly within the ZnO/COPs, thanks to weak interactions between the polyurethane matrix and acetic acid that favour the transport of the acid up to reach the zinc oxide surfaces, resulting in a synergistic effect. The ZnO/COPs composites showed significantly enhanced adsorption capacities of acetic acid surpassing those of the activated carbon benchmark, with the advantage of being easily handled and movable, without the health issues and risks associated to the use of non-confined micro/nano-powders.

Effects of Ambience on Thermal-Diffusion Type Ga-doping Process for ZnO Nanoparticles

Various annealing atmospheres were employed during our unique thermal-diffusion type Ga-doping process to investigate the surface, structural, optical, and electrical properties of Ga-doped zinc oxide (ZnO) nanoparticle (NP) layers. ZnO NPs were synthesized using an arc-discharge-mediated gas evaporation method, followed by Ga-doping under open-air, N2, O2, wet, and dry air atmospheric conditions at 800 °C to obtain the low resistive spray-coated NP layers. The I–V results revealed that the Ga-doped ZnO NP layer successfully reduced the sheet resistance in the open air (8.0 × 102 Ω/sq) and wet air atmosphere (8.8 × 102 Ω/sq) compared with un-doped ZnO (4.6 × 106 Ω/sq). Humidity plays a key role in the successful improvement of sheet resistance during Ga-doping. X-ray diffraction patterns demonstrated hexagonal wurtzite structures with increased crystallite sizes of 103 nm and 88 nm after doping in open air and wet air atmospheres, respectively. The red-shift of UV intensity indicates successful Ga-doping, and the atmospheric effects were confirmed through the analysis of the defect spectrum. Improved electrical conductivity was also confirmed using the thin-film-transistor-based structure. The current controllability by applying the gate electric-field was also confirmed, indicating the possibility of transistor channel application using the obtained ZnO NP layers.

Growth of ZnO/Bi2S3 electron transport layer films to improve the efficiency and stability of organic solar cells

Zinc oxide (ZnO) grown on indium tin oxide (ITO) glass substrates were decorated with bismuth sulfide (Bi2S3) nanorods by thermal decomposition of bismuth ethylxanthate precursor method. Different thicknesses of ZnO/Bi2S3 bilayer films were prepared by controlling the spin speed of bismuth xanthate precursors (5000, 6000 and 7000 rpm, respectively) and applied as the electron transport layer (ETL) in organic solar cells (OSCs) with the structure of ITO/ZnO/Bi2S3/PM6:Y6/MoO3/Ag. The effects of different thickness of ZnO/Bi2S3 as ETLs on device performance and stability were investigated in detail. Firstly, the device based on ZnO/Bi2S3 6000 rpm as ETL confirmed excellent performance with the power conversion efficiency (PCE) of 12.50%, which was improved by 28.60% of the reference device without Bi2S3 nanorods coated. XRD and SEM results showed that Bi2S3 nanorods covered the ZnO surface well. Electrical conductivity and the current density-voltage (J-V) curve results under dark conditions showed that when Bi2S3 nanorods were added between the active layer and ZnO, the interfacial conductivity can be effectively increased and improved the interfacial carrier transport efficiency. Secondly, the stability results of the ZnO/Bi2S3 6000 rpm device demonstrated that the PCE of ZnO/Bi2S3 6000 rpm device was maintained about 91.54%, while that of pure ZnO as ETL was maintained about 75.26% of the original value after 33 h in air. This means that the ZnO/Bi2S3 prepared by thermal decomposition of the bismuth xanthate precursor on ZnO is a promising electron transport material in OSCs.

New Approaches to Increasing the Superhydrophobicity of Coatings Based on ZnO and TiO2

The work presented is devoted to new approaches to increasing the superhydrophobic properties of coatings based on zinc oxide (ZnO) and titanium dioxide (TiO2). There is an innovation in the use of inorganic coatings with a non-polar structure, high melting point, and good adhesion to ZnO, in contrast to the traditionally used polymer coatings with low performance characteristics. The maximum superhydrophobicity of the ZnO surface (contact angle of 173°) is achieved after coating with a layer of hematite (Fe2O3). The reason for the abnormally high hydrophobicity is a combination of factors: minimization of the area of contact with water (Cassie state) and the specific microstructure of a coating with a layer of non-polar Fe2O3. It was shown that the coating of ZnO structures with bimodal roughness with a gold (Au) layer that is 60-nm thick leads to an increase in the wetting contact angle from 145° to 168°. For clean surfaces of Au and hematite Fe2O3 films, the contact angle wets at no more than 70°. In the case of titanium oxide coatings, what is new lies in the method of controlled synthesis of a coating with a given crystal structure and a level of doping with nitrogen using plasma technologies. It has been shown that the use of nitrogen plasma in an open atmosphere with different compositions (molecular, atomic) makes it possible to obtain both a hydrophilic (contact angle of 73°) and a highly hydrophobic surface (contact angle of 150°).

Facile synthesis of silver modified zinc oxide nanocomposite: An efficient visible light active nanomaterial for bacterial inhibition and dye degradation

The present study reports the synthesis of silver (Ag) decorated zinc oxide (ZnO) nanocomposite via green synthesis method by using Acacia arabica plant leaves extract as both reducing and capping agent. The results clearly indicate a uniform distribution of Ag nanoparticles (NPs) over ZnO surface. Various analytical and spectroscopic techniques were used for investigating the formation and morphology of as-synthesized Ag/ZnO nanocomposites. Emergence of SPR at 424 and 378 nm confirmed the synthesis of AgNPs and ZnO respectively. The confirmation of elemental composition and crystal structure of prepared nanomaterials (NMs) was carried out via EDX and XRD analysis. Results obtained from HRTEM and SEM analysis indicated small sized spherically shaped NMs. The as-synthesized was checked for its photocatalytic activity towards degradation of MB in the presence as well as absence of light irradiation. Results of degradation study revealed that Ag/ZnO exhibits remarkable photocatalytic activity in the presence of light whereby removing 90% of MB within 80 min. Moreover, the antibacterial activity of synthesized nanocomposite was examined in both visible light and dark conditions. The experiment showed that nanomaterial depicts enhanced antibacterial activity in light in comparison to dark. The results showed that the inhibition diameter of Ag/ZnO nanocomposite in light was found to be 18 (±0.2), 22 (±0.3) against E. coli and S. aureus respectively. The inhibition zone of the said nanomaterial against E. coli and S. aureus in dark was 11 (±0.3), 14 (±0.5) respectively. These results conclude that activity is delivered both in the presence of visible light and dark but efficiency of antibacterial activity is found to be more in visible light in comparison.

Catalytic hydrogen evolution reaction on surfaces of metal-nanoparticle-coated zinc-based oxides by first-principles calculations

Using first-principles calculations, we investigate the hydrogen evolution reaction (HER) on the noble-metal-nanoparticle-coated zinc or zinc-tin oxide surfaces. Among the six catalytic structures, the adsorption free energy of Au/ZnO structure is closest to zero. The relative energy diagrams reveal that Volmer-Heyrovsky mechanism on the NP (oxide) reactive site dominants the HER process on NP/ZTO (Pt/ZnO and Au/ZnO) structures. However, comparing the adsorption free energy and primary energy barrier of the prefer path of each structure, the Pt/ZnO structure shows the best performance for the HER process.