Structure Of Oxide Research Articles

Simulation of high efficiency hybrid FTO/TiO2/CH3NH3SnI3/RGO based solar cell using SCAPS-1D

A hybrid structure of fluorine-doped tin oxide (FTO)/titanium dioxide (TiO2)/methylammonium tin triiodide (CH3NH3SnI3)/reduced graphene oxide (RGO) based solar cell has been designed and simulated using SCAPS-1D simulation tool. The three layers of the solar cell have been organized like TiO2 acting as an electron transporting layer (ETL), CH3NH3SnI3 serving as the photon absorption layer, and reduced graphene oxide (RGO) acting as the hole transporting layer (HTL). The thickness of the ETL and HTL layers are maintained at 300 nm each. The absorption layer thickness has been optimized and kept at 450 nm to get enhanced efficiency. The experimental absorption data from the referred articles of the materials are incorporated with the simulation to obtain convincing result. Simulated device parameters, such as efficiency, open-circuit voltage, short-circuit current density, and fill factor have been found to be 19.30 %, 1.070 V, 41.66 mA/cm2, and 43.27 %, respectively at 300 K temperature. Moreover, a study of the absorption layer defect density (109–1017 cm−2) has also been conducted for the device, revealing an almost inverse proportionality with the efficiency of the device. In addition, the device FTO/TiO2/CH3NH3SnI3/RGO has been examined with the various temperature range from 270 K to 400 K. The device, with a high offset band structure and high mobility ETL and HTL layers, shows promising candidate for solar cell applications.

Elusive supported surface M2Ox dimer active site (M = Re, W, Mo, Cr, V, Nb, and Ta)

Supported transition metal oxide catalysts are extensively used as heterogeneous catalysts for various energy, chemical, and environmental applications. The molecular structures of dehydrated surface metal oxide phases are crucial for understanding structure-activity/selectivity relationships that guide the design of enhanced catalysts. Some early studies suggested that dimeric (aka binuclear) surface metal oxide sites were more active/selective than monomeric (aka mononuclear) sites, prompting interest in synthesizing catalysts with supported dimeric metal oxide structures. This review examines the literature on dehydrated silica-based supported group 7-5 MOx catalysts (ReOx, WOx, MoOx, CrOx, VOx, NbOx, and TaOx on SiO2, MCM-41, AlOx/SiO2, and H-ZSM-5) for their surface metal oxide structures. In situ Raman, extended x-ray absorption fine structure, and ultraviolet-visible spectroscopy indicate that monomeric surface MOx structures predominate in all such catalysts. Therefore, the cursory use of dimeric surface M2Ox sites in catalytic mechanisms and reaction models in heterogeneous catalysis by supported metal oxides is questionable, and moving forward, the invoking of supporting dimeric surface M2Ox sites should be critically examined and backed up with direct spectroscopic methods.

Effect of Electron Irradiation on the Optical Properties of Zinc Oxide Powder Modified by Magnesium Oxide Nanoparticles

The effect of modifying ZnO powders with MgO nanoparticles (with a concentration of 0.1–10 wt. %) on their diffuse reflectance spectra in the region of 0.2–2.5 μm before and after irradiation with 30 keV electrons was studied. Modification of ZnO powder was carried out by MgO nanopowder with concentrations from 0.1 to 10 wt. % using a solid-state method at 650°C heating temperature. X-ray diffraction analysis showed that this method of modification there is no formation of additional phases. It has been established that zinc oxide structure symmetry belongs to the P63mc space group, magnesium oxide – to the Fm–3m space group. The spectral reflectance of such powders in the visible region is over 90%. Under irradiating by 30 keV electrons of initial and modified ZnO powders, as well as MgO nanopowder, a decrease in their reflectance recorded in the entire studied region of the spectrum. It has been established that modification with MgO nanoparticles at a concentration of 3 wt. % leads to an increase in radiation resistance by a factor of 1.32 compared to unmodified samples. This effect is determined by the sink of radiation defects on the large specific surface area of nanoparticles.

Fast inverse design of microwave and infrared Bi-stealth metamaterials based on equivalent circuit model

This work proposed a fast inverse design method for microwave and infrared (IR) bi-stealth metamaterials based on the equivalent circuit model (ECM). Using this method, we designed a microwave and IR bi-stealth metamaterial by deploying a multilayered structure of the indium tin oxide (ITO) film based metasurface. First, the IR emissivity of the ITO film was calculated in the framework of the ECM. Then, an ITO metasurface was proposed to implement low IR emission and high microwave transmission simultaneously. Based on the ECM of the square patch, the ECM of the whole metamaterial was established at the microwave band. An inverse design program was built by incorporating the ECM with genetic algorithm (GA). Structure parameters of the metamaterial were optimized by GA to achieve the broadest microwave stealth bandwidth for the given thickness. Finally, the sample of the optimized bi-stealth metamaterial was prepared and tested. The calculated, simulated, and measured results are in good agreement, showing that such a metamaterial has an IR emissivity of 0.18 in the band from 3 to 14 μm and an efficient microwave stealth band from 4.8 to 17 GHz with a thickness of 4.9 mm. The proposed method will benefit the design and application of microwave and IR bi-stealth metamaterials.

Investigating the Local Bonding Structure of Amorphous Zinc Tin Oxide to Elucidate the Effect of Altering the Intercation Ratio.

In this paper, the local bonding structure in amorphous zinc tin oxide (a-ZTO) is probed using a combination of XANES and EXAFS techniques at the Zn and Sn K-edges to gain insight into charge carrier generation in the material. a-ZTO is prepared using two growth methods; spray pyrolysis and magnetron sputtering. It is seen that a-ZTO grown by magnetron sputtering shows no changes in the chemical environment as the cation ratio is varied; meanwhile, XANES analysis of spray pyrolysis grown samples shows alterations to spectra likely due to the effects caused by different precursors. Although a slight shift in Sn-O bond length is visible between magnetron sputtered and spray grown samples, no correlation could be discerned between bond length and variation in cation ratio. It is concluded that a-ZTO, while amorphous over longer ranges, is locally composed of ZnO and SnO2 "building blocks". An alteration in the cation ratio changes the hybridization at the conduction band minimum, resulting in the observed variation in the mobility, charge carrier concentration, and bandgap.

Structure, Raman spectroscopy, and magnetic properties of new Al, Ga, and Mn-based high entropy oxides

Recent advancements in high entropy oxides (HEOs) have sparked significant interest as a promising frontier in materials research, revolutionizing the landscape of material design and properties. They exhibit outstanding stability, intriguing functional properties, and unparalleled design flexibility enabled by the inclusion of multiple cations in these materials. In this study, we successfully stabilized several new high entropy spinel oxides with compositions (Ni0.2(Mg/Mn)0.2Co0.2Cu0.2Zn0.2)B2O4 (B = Al, Ga, Mn). The room temperature X-ray diffraction (RT-XRD), field emission scanning electron microscopy (FE-SEM), and energy dispersive spectroscopy (EDS) measurements highlight the crystal structure of the materials with excellent chemical homogeneity at the micro-scale. RT-XRD and Raman spectroscopy confirmed the formation of single-phase cubic spinel structures. However, the Mn-based sample exhibited tetragonal distortion. Magnetic measurements show remarkable variation in the magnetic properties: (Ni0.2Mg0.2Co0.2Cu0.2Zn0.2)Mn2O4 shows complex ferrimagnetic behavior, Al and Ga based diamond lattice (Ni0.2Mg0.2Co0.2Cu0.2Zn0.2)B2O4 (B = Al and Ga) materials revealed extremely high magnetic frustration and absence of magnetic ordering down to 1.8 K, indicative of exotic frustrated state. Magnetic transitions (spin-glass like) are observed in (Ni0.2Mn0.2Co0.2Cu0.2Zn0.2)B2O4 (B = Al and Ga) materials. Our study highlights the potential to finely tune the magnetic responses through compositional engineering, thus paving the way for the development of tailored magnetic materials for various applications.

Enhancement of peroxymonosulfate activation with nickel foam-supported CuCo2O4 for tetracycline degradation: Performance and mechanism insights

The modulation of bimetallic oxide structures and development of efficient, easily recoverable catalysts are expected to effectively overcome the limitations associated with powdered catalysts in activating peroxymonosulfate (PMS). In this study, CuCo2O4 was successfully immobilized on the surface of nickel foam (NF) via an electrodeposition-calcination procedure, with highly efficient activation of PMS for tetracycline (TC) degradation (0.55 min−1). Besides acting as a support carrier and providing ample active sites, NF mediated electron transport, prevented the leaching of metal ions and enhanced the efficiency of recycling. Density functional theory (DFT) calculations and experimental tests illustrated that Cu/Co dual-sites can efficiently adsorb PMS, enabling simultaneous reduction and oxidation reactions. The dual-site synergy substantially decreased the adsorption barrier and increased the electron transfer rate. Especially, the Cu+/Cu2+ redox couple acted as an electron donor and facilitated rapid charge transfer, leading to the conversion of Co3+ to Co2+. Moreover, the CuCo2O4@NF + PMS system effectively eliminated TC by employing radical pathways (SO4•−, •OH) and nonradical processes (1O2, e−). Therefore, this study introduces a new approach to overcome the limitations of powdered bimetallic oxides, providing a promising solution for practical applications.

Impact of Synthesis Method on the Structure and Function of High Entropy Oxides.

The term sample dependence describes the troublesome tendency of nominally equivalent samples to exhibit different physical properties. High entropy oxides (HEOs) are a class of materials where sample dependence has the potential to be particularly profound due to their inherent chemical complexity. In this work, we prepare a spinel HEO of identical nominal composition by five distinct methods, spanning a range of thermodynamic and kinetic conditions: solid state, high pressure, hydrothermal, molten salt, and combustion syntheses. By structurally characterizing these five samples across all length scales with a variety of X-ray methods, we find that while the average structure is unaltered, the samples vary significantly in their local structures and their microstructures. The most profound differences are observed at intermediate length scales, both in terms of crystallite morphology and cation homogeneity. As revealed by X-ray fluorescence microscopy ideal cation homogeneity is achieved only in the case of combustion synthesis. These structural differences in turn significantly alter the observed functional properties, which we demonstrate via characterization of their magnetic response. While ferrimagnetic order is retained across all five samples, the sharpness of the transition, the size of the saturated moment, and the coercivity all show marked variations with synthesis method. We conclude that the chemical flexibility inherent to HEOs is complemented by strong synthesis method dependence, providing another axis along which to optimize these materials for a wide range of applications.

Layered 3d Transition Metal‐Based Oxides for Sodium‐Ion and Lithium‐Ion Batteries: Differences, Links and Beyond

AbstractDue to their stable crystal framework, promising energy density, and structural versatility, layered 3d transition metal oxides have emerged as the preferred cathodes for lithium‐ion batteries (LIBs) and sodium‐ion batteries (SIBs). While extensive research has individually addressed the lithium and sodium 3d transition metal layered oxides, the differences and interconnections between the two types of materials have largely been overlooked. Effectively utilizing these summaries is essential for driving innovative structural designs and inspiring new insights into the structure‐property relationships. This review comprehensively bridges this gap by meticulously examining the disparities and links in the behavior of the layered oxides upon Li+ and Na+ storage and transfer. Key aspects, including atomic and electronic structure, phase transition mechanisms, charge compensation mechanisms and electrochemical kinetics, are carefully summarized. The implications of these aspects on the battery cycle life, energy density, and rate capability are thoroughly discussed. Additionally, by leveraging the unique characteristics of each oxide structure, this review explores the interconnection between lithium and sodium layered oxides in depth. Finally, a concise perspective on future targets and direction of 3d layered oxides is deduced and proposed.

Interlayer engineered bilayered V₂O₅ NPs as saturable absorbers for infrared ultrashort pulse generation

Interlayer engineering offers a promising approach to modifying the structure of layered vanadium-based oxides, enhancing their saturable absorption effect and making them a desirable choice for developing infrared wavelength-range photonics devices. This experimental work synthesizes interlayer vanadium pentoxide (V2O5) using hydrothermal techniques to produce an excellent saturable absorber (SA). The interlayer engineering strategy enhances strong saturable absorption and self-defocusing effects in V2O5-based SA, enabling the generation of ultrashort pulses in the infrared region. Their superior nonlinear optical characteristics are demonstrated by a modulation depth of 13.9 % and saturation intensity of 0.42 GW cm−1, respectively. By utilizing a transmission coupling fiber-based V2O5-SA inside an Er-doped fiber laser cavity, a passively Q-switched (PQS) laser with a narrow pulse width of 2.78 μs and signal-to-noise ratio (SNR) ∼50 dB is realized for the first time. Furthermore, we explore a V2O5 NPs-SA long-term stability and high damage threshold. The results not only offer additional proof of the capable potential of interlayer V2O5 as a photo-bleaching absorber for realizing pulsed lasers in the NIR band but also cover the method for advancing their probable applications in optoelectronic devices.

Investigating the kinetics, thermodynamic properties, and mechanisms of high-temperature oxidation in ferrosilicon alloys

Ferrosilicon alloys are widely used as a deoxidizer in steelmaking due to their strong oxygen affinity and high deoxidizing ability. However, compared to other deoxidizers, relatively few studies have been conducted on its kinetics, thermodynamics, and reaction mechanisms. This study aims to investigate the oxidation characteristics of ferrosilicon alloys at different particle sizes, reaction temperatures, and reaction times, and to evaluate their oxidation structure and reaction characteristics. To achieve this, we used the response surface methodology (RSM) to establish a multi-factor model. The results show that reaction time and reaction temperature are the primary factors affecting the oxidation rates, followed by particle size. Wagner’s law was used to verify that the change in oxidation mass follows the parabolic rate law and was discussed in relation to other alloys. Additionally, the application of the volumetric model (VM) and the unreacted core model (URCM) in calculating the activation energy (E) was compared to understand the kinetic characteristics of ferrosilicon alloys more comprehensively. Specifically, when the particle size range increases from 0.075–––0.1 mm to 0.3–––0.5 mm, the estimated E of the VM model increases from 81.82 KJ·mol−1 to 87.84 KJ·mol−1. The URCM model’s result increases from 91.53 KJ·mol−1 to 97.21 KJ·mol−1. Additionally, we evaluated the thermodynamic feasibility of ferrosilicon alloys at temperatures ranging from 273.15 K to 1673.15 K using HSC Chemistry software. This paper describes in detail the oxide layer structure and oxidation reaction process of ferrosilicon alloys and proposes an oxidation reaction mechanism, providing a reliable theoretical basis for the application system of ferrosilicon alloys.

Enhancing charge extraction in BiVO4 photoanodes by ZrCl4 treatment of SnO2 hole-blocking layers

In the search for more efficient and sustainable photoelectrochemical devices, BiVO4 is nowadays one of the best-performing photoanode material, with favourable band structure for water oxidation. However, BiVO4 photoanodes face challenges such as poor charge transport and slow kinetics. To address these issues, SnO2 films are commonly used as hole blocking layers, reducing recombination rate and enhancing charge lifespan and overall productivity. Yet, this method encounters problems like high defect concentrations at the SnO2/BiVO4 interface and pinholes in the SnO2 layer, which lead to charge recombination. In this study, we explore a ZrCl4 treatment to improve the effectiveness of SnO2 as a hole-blocking layer in BiVO4 photoanodes. Our findings, supported by detailed optoelectronic characterization and continuous and modulated electrochemical analysis, reveal that ZrCl4 treatment significantly enhances the hole-blocking properties of SnO2. This treatment results in a 37 % increase in photocurrent density at 1.23 VRHE and a 40 mV shift in the onset voltage, demonstrating a substantial improvement in overall photoanode efficiency.

Optimizing methanol synthesis from CO2: Are bulk hexagonal indium oxide structures superior to cubic ones?

Recently, catalysts based on bulk indium oxide (In2O3) have been used in CO2 valorization; however, several studies correlate crystal phase with performance without considering possible changes during the reaction. In this context, we investigated different crystal phases of bulk In2O3 (pure cubic, hexagonal, or mixed-phased) in CO2 hydrogenation, where we observed variations in catalytic activity associated with phase transitions occurring under reaction conditions. We systematically compared the crystal phase and surface area before and after the reaction, showing that, at 350°C, independent from the initial In2O3 structure, there is a tendency to form the cubic phase accompanied by the loss of surface area. To reach these results, we employed various synthetic methods that tailored structural and textural characteristics to achieve desired properties; for the first time, we obtained a cubic major mixed-phase In2O3 structure at a 3-hour synthesis time by using a microwave-assisted method. Such material presented the best methanol productivity. Thus, as not previously reported, our results revealed that utilizing bulk hexagonal In2O3 may not be interesting under this temperature; also, a higher surface area does not necessarily provide improved conversion rates. XPS, XRD, EPR, MEV, N2 physisorption, CO2-TPD, and H2-TPR were performed and corroborated our investigations.

In-situ prepared co exsolution nano catalyst for efficient hydrogen generation via ammonia decomposition

Active and durable catalytic material for ammonia (NH3) decomposition reaction is attracting attentions for utilization of NH3 as an innovative hydrogen carrier. In this study, diverse single metal and alloy nano catalysts are prepared via in-situ exsolution method and their NH3 decomposition properties are evaluated. Transition metal cations (Ni, Co, Fe ions) are doped into the La0.43Ca0.37MxNyTi1-(x+y)O3-δ (LCMNT) perovskite oxide structure and exsolved on its surface as supported nano particles under reduction condition. The maximum doping level and chemical composition of exsolution catalysts are investigated to optimize their NH3 decomposition activity. The exsolution catalyst demonstrates improved NH3 decomposition characteristics compared to conventionally prepared infiltration catalysts, indicating higher conversion efficiency and H2 production rate. The exsolved nano catalysts also exhibit great thermochemical stability against catalyst agglomeration or surface nitriding. The results obtained in this study suggest the potential utilization of exsolution catalysts for on-site production of H2 through NH3 decomposition catalysis.

Putting error bars on density functional theory

Predicting the error in density functional theory (DFT) calculations due to the choice of exchange–correlation (XC) functional is crucial to the success of DFT, but currently, there are limited options to estimate this a priori. This is particularly important for high-throughput screening of new materials. In this work, the structure and elastic properties of binary and ternary oxides are computed using four XC functionals: LDA, PBE-GGA, PBEsol, and vdW-DF with C09 exchange. To analyze the systemic errors inherent to each XC functional, we employed materials informatics methods to predict the expected errors. The predicted errors were also used to better the DFT-predicted lattice parameters. Our results emphasize the link between the computed errors and the electron density and hybridization errors of a functional. In essence, these results provide “error bars” for choosing a functional for the creation of high-accuracy, high-throughput datasets as well as avenues for the development of XC functionals with enhanced performance, thereby enabling the accelerated discovery and design of new materials.

EFFECT OF SILVER DOPING ON IRON OXIDE ELECTRICAL PROPERTIES

Iron silver oxide (Agx[Formula: see text]O3; [Formula: see text]) structure for photoelectrochemical (PEC) water splitting was grown by RF–DC co-sputtering of an iron–silver target in argon/oxygen plasma mixtures at 300°C, followed by thermal annealing at 560°C. The chemical composition and structure of the deposited film can be tuned by controlling the metal doping and the annealing temperature. The thermal treatment extensively improves the PEC water-splitting performances of the films. XRD patterns of AgxFe[Formula: see text]O3 shown in the figure can be indexed to the hexagonal structure of silver oxide and the rhombohedral structure of hematite and new X-ray Diffraction (XRD) peaks of AgxFe[Formula: see text]O3 structure. The annealing and doping process seems to cause a serious change in the crystal structure of the thin film, it showed a serious change in its electrical properties. The electrical parameters of resistance for thin films were measured using the Hall measurement method at room temperature. With Hall measurements, the n-type carrier concentration of the Fe2O3 structure was calculated, and it was observed that its resistance was 1[Formula: see text]M[Formula: see text]. Likewise, it was observed that AgxFe[Formula: see text]O3 exhibited an n-type carrier concentration, and its resistance was calculated to be 0.5[Formula: see text]M[Formula: see text]. The conductivity change is based on silver doping. The doping process seems to cause a change in the bandgap of the thin film, it showed a change in its optical properties. The film’s optical absorption was measured by UV–Vis photo spectroscopy. Subsequently, the structural and topographic properties of AgxFe[Formula: see text]O3 structures were investigated by high-precision characterization devices.

Chemically Bonded Biphase Coating of Ni-Rich Layered Oxides with Enhanced High-Voltage Tolerance and Long-Cycle Stability.

Stabilizing the crystalline structure and surface chemistry of Ni-rich layered oxides is critical for enhancing their capacity output and cycle life at a high cutoff voltage. Herein, we adopted a simple one-step solid-state method by directly sintering the Ni0.9Co0.1(OH)2 precursor with LiOH and Ta2O5, to simultaneously achieve the bulk material synthesis of LiNi0.9Co0.1O2 and in situ construction of a rock-salt Ta-doped interphase and an amorphous LiTaO3 outer layer, forming a chemically bonded surface biphase coating on LiNi0.9Co0.1O2. Such a cathode architectural design has been demonstrated with superior advantages: (1) eliminating surface residual alkali, (2) strengthening the layered oxygen lattice, (3) suppressing bulk-phase transformation, and (4) facilitating Li-ion transport. The obtained cathode exhibits excellent electrochemical performance, including a high initial reversible capacity of 180.3 mAh g-1 at 1.0 C with 85.5% retention after 300 cycles (2.8-4.35 V) and a high initial reversible capacity of 182.5 mAh g-1 at 0.2 C with 87.6% retention after 100 cycles (2.8-4.5 V). Notably, this facile and scalable electrode engineering makes Ni-rich layered oxides promising for practical applications.

Intercalation of V2O5 and Polypyrrole into a Graphene Oxide Layer: A Hybrid Multifunctional Photothermal Structure for Efficient Solar Evaporation, Water Purification, Disinfection, and Power Production.

Development of a hybrid multifunctional photothermal structure with multifunctional capabilities is deliberated as an effective approach for harvesting abundant solar energy for sustainable environmental applications. Achieving enhanced solar to thermal conversion efficiency utilizing a suitably designed, environmentally compatible thermal management structure however remains a significant challenge. Herein, we report the intercalation of V2O5 and polypyrrole into a graphene oxide layer to design a hybrid photothermal assembly (PPy-V2O5-GO) and its multifunctional proficiencies. The hybrid photothermal structure demonstrated synergistic photothermal conversion, buoyant porous structure sustaining water transmission, and efficient steam release. V2O5 and polypyrrole-intercalated optimized graphene oxide structure attained an evaporation rate of 1.9 kg m-2 h-1 with a conversion efficiency of 92% under 1 sun solar radiation. At maximum, the assembly's surface temperature hit 64 ± 2 °C, suggesting its suitability as a solar water purifier. Outdoor experiments suggest the evaporator assembly's capability to accumulate a total output of 15 kg m-2 over a single day. Cell viability investigations revealed strong antimicrobial properties of PPy-V2O5-GO against both Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus bacteria, eliminating nearly all under 1 sun, making it a potential candidate for photothermal therapy. Furthermore, when combined with a commercial thermoelectric module, the framework displayed exceptional photothermal conversion efficiency, hinting at its potential for electrical power generation. The integration of PPy-V2O5-GO with a Bi2Te3-based thermoelectric module significantly boosted the thermoelectric generator's performance, offering an enhanced power output of 2.8 mW and a high power density of 1.24 mW/cm2, making them suitable for off-grid or remote-area application. Overall, the PPy-V2O5-GO photothermal assembly's stability, lack of leaching, effectiveness in producing pure water from seawater, antimicrobial efficacies, and recyclability make it an excellent choice for sustainable water treatment and power generation.

3D Porous Graphene Architecture Integrated with Cu2O for Enhanced Electrochemical Sensing Performance.

Construction and functionalization of a 3D graphene architecture are crucial to harness and extend the unique features of graphene and thus essential for its numerous conventional and novel applications. Herein, a 3D honeycomb-patterned porous graphene architecture is constructed through a facile and low-cost self-assembly process and then integrated with Cu2O nanoparticles via a simple electrodeposition procedure. The 3D porous graphene structure is prepared by the breath figure method using a graphene oxide (GO)-based complex in which GO is modified by a surfactant as the casting material. Benefiting from the intercalation of the surfactant between the GO nanosheets and the fabrication of a 3D porous structure, the aggregation inhibition of GO nanosheets and increases in accessible surface area are realized at both nano- and microscales, resulting in good electrochemical performance. Moreover, the deposition of Cu2O nanoparticles can further improve the electrochemical sensing performance of the porous reduced graphene oxide (rGO) structure. Extremely low detection limit (30.72 nM) with a linear range of 0 μM to 30 μM, excellent anti-interference, repeatability, reproducibility, stability, and high accuracy for actual sample testing are shown when the 3D porous Cu2O/rGO film is applied as an electrochemical sensor for DA detection. This work provides not only a superior electrochemical biosensor but also a simple, yet effective and general strategy for the construction and functionalization of a 3D graphene structure.

Contributions of Surface Oxidizing Species and Cu+ to the Antibacterial Activities of Cu2O with Different Crystalline Structures.

Although precise regulation of the crystalline structures of metal oxides is an effective method to improve their antibacterial activities, the corresponding mechanisms involved in this process are still unclear. In this study, three kinds of cuprous oxide (Cu2O) samples with different structures of cubes, octahedra, and rhombic dodecahedra (c-Cu2O, o-Cu2O, and r-Cu2O) have been successfully synthesized and their antibacterial activities are compared. The antibacterial activities follow the order of r-Cu2O > o-Cu2O > c-Cu2O, revealing the significant dependence of the antibacterial activities on the crystalline structures of Cu2O. Quenching experiments, as well as the NBT and DPD experiments indicate that ≡CuII─OO• superoxo and ≡CuII─OOH peroxo, instead of •OH, O2•-, and H2O2, are the primary oxidizing species in the oxidative damage to E. coli. Raman analysis further confirms the presence of both ≡CuII─OO• superoxo and ≡CuII─OOH peroxo on the surface of r-Cu2O. On the other hand, the NCP experiment reveals that Cu+, instead of Cu2+, also contributes to the antibacterial process. This study provides new insight into the antibacterial mechanisms of Cu2O.