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The synergistic effects study between metal oxides and graphene on far-infrared emission performance
摘要： Materials with high far-infrared (FIR) emissivity are quiet promising in modern medical care field, owing to its accelerating effects to blood circulation and metabolism. In this work, we synthesized two serials composites: MnO2/graphene nanoplate (GNPs) and Fe2O3/GNPs via in situ hydrothermal process. Positive synergistic effects on FIR emission were shown between either MnO2 or Fe2O3 and GNPs. In particular, MnO2/GNPs (2%) showed a super high FIR emissivity of 0.981 compared with pristine MnO2 (0.940) and GNPs (0.878) in the wavelength of 8–14 μm. The FIR emissivity of Fe2O3/GNPs (1%) was up to 0.953 that was much higher than those of pristine Fe2O3 (0.877) and GNPs as well. Benefiting from the characteristics of graphene such as large specific surface, lightweight and thin-layer, MnO2 and Fe2O3 nanocrystals grew on graphene surface and formed different morphologies. A coralloid-like morphology was formed to MnO2/GNPs (2%), suggesting a highly porous surface that meant more unstable atoms or molecules were exposed. The morphologies of metal oxide/GNPs were thought to relate with the good synergistic effects between GNPs and metal oxides. Therefore, this work provides that metal oxides/graphene composites have promising application for high FIR emission materials.
关键词： MnO2,Graphene,Far-infrared emission,Fe2O3
更新于2025-09-23 15:21:01
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Photoelectrochemical performances of Fe2O3 nanotube films decorated with cadmium sulfide nanoparticles via photo deposition method
摘要： Hematite is an appropriate compound for photoelectrochemical water splitting. However, passive surface state, high recombination rate of the photo induced electron-hole pairs and poor and slow charge transfer kinetics restrict the performance of hematite. In this work, CdS/Fe2O3NTs samples have been successfully prepared by coating of CdS nanoparticles on the surface of the self-organized Fe2O3NTs via photo deposition technique in order to enhance charge separation and charge transfer kinetics. FESEM (Field Emission Scanning Electron Microscopy), XRD (X-ray diffraction), DRS (Diffraction Reflection Spectroscopy) and XPS (X-ray Photoelectron Spectroscopy) analyses have been used to characterize the CdS/Fe2O3NTs photoelectrodes obtained. CdS/Fe2O3NTs has an intense visible light absorption and displays a red-shift of the band edge in comparison with the bare Fe2O3NTs, according to DRS test. The photocurrent density of Fe2O3NTs increased approximately 5 times upon coating with CdS, as shown by photoelectrochemical measurements, indicating the significant role of the introduction of CdS in the enhancement of photo catalytic activity. CdS/Fe2O3NTs may be promising and effective photoanodes in PEC water splitting given their simple preparation and good performance.
关键词： Cadmium sulfide,Photo deposition,Fe2O3 nanotube,Photoelectrochemical water splitting
更新于2025-09-23 15:21:01
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Semiconductor α-Fe <sub/>2</sub> O <sub/>3</sub> Hematite Fabricated Electrode for Sensitive Detection of Phenolic Pollutants
摘要： Hematite (α-Fe2O3) semiconductor is an abundant and non-toxic catalyst for different (photo)electrochemical reactions. In this work, a selective p-nitrophenol sensor was developed by fabricating a thin-layer of a glassy carbon electrode (GCE) with 5% nafion coating binders onto α-Fe2O3 thin film synthesized by a simple and inexpensive process. High sensitivity including long-term stability, and enhanced linear dynamic range, electrochemical performance towards p-nitrophenol were achieved by a reliable current-voltage method. A linear calibration curve was observed over a wide range of p-nitrophenol concentrations. Very low detection limit (0.6 ? 0.02 nM), good limit of quantification (2.0 nM) and high sensor sensitivity (K = 74.1 μA?cm(cid:0) 2) are calculated based on noise to signal ratio of ～ 3 N/S. Very importantly, the detection range covers over 7 orders of magnitude concentrations, from nM to mM. Figures of merits are comparable with best reported results whilst using a very simple device configuration. We show that hematite is an excellent material for the development of chemical sensors to detect hazardous compounds for environmental safety in a broad scale of concentrations.
关键词： Environmental safety,Sensitivity,p-Nitrophenol sensor,Hematite α-Fe2O3,Glassy carbon electrode
更新于2025-09-23 15:21:01
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Ti-MOF derived TixFe1-xOy Shells Boost Fe2O3 Nanorod Cores for Enhanced Photoelectrochemical Water Oxidation
摘要： TixFe1-xOy shells, in-situ formed from thermal treatment of a Ti-containing metal organic framework, NH2-MIL-125(Ti), significantly boost the photoelectrochemical water oxidation efficiency of Fe2O3 nanorod cores. The NH2-MIL-125(Ti) was coated on the surface of the Fe2O3 nanorods with a solvothermal process, followed by a two step calcination to afford the TixFe1-xOy shell/Fe2O3 core nanorod arrays. The TixFe1-xOy shell/Fe2O3 core nanorod array electrode exhibited much improved photoelectrochemical activities over the pristine Fe2O3 nanorod array electrode, boosting photo-current densities to 26.7 folds of that achieved by the pristine Fe2O3 nanorod array electrode at 1.23 V (vs. RHE) under illumination of simulated sun light of AM 1.5G. The success may be attributed to the much enhanced charge separation enabled by the hole trapping heterojunction of TixFe1-xOy shell/Fe2O3 core. The photoelectrochemical stability of the TixFe1-xOy shell/Fe2O3 core nanorod array electrode was excellent, retaining 98.9% of the initial photo-current density after a 5 hr continuous operation. This work is the first demonstration of MOF derived core-shell heterojunction for large improvements of PEC water splitting efficiencies, and can be readily extended to a wide range of catalyst design.
关键词： NH2-MIL-125(Ti),Fe2O3 nanorod,TixFe1-xOy shell/Fe2O3 core nanorod arrays,photoelectrochemical water oxidation,photoanode
更新于2025-09-23 15:19:57
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Boosting multiple interfaces by co-doped graphene quantum dots for high efficiency and durability perovskite solar cells
摘要： Organic-inorganic hybrid perovskite solar cells (PSCs), as the most rapidly developing next-generation thin-film photovoltaic technology, have attracted extensive research interests, yet their efficiency, scalability, and durability remain challenging. IH.(cid:8)2O3 could be served as electron transporting layer (ETL) of planar PSCs, which exhibited a much higher humidity and UV light-stability compared to TiO2-based planar PSCs. However, the photovoltaic conversion efficiency (PCE) of Fe2O3-based device was still below 15% because of poor interface contact between IH Fe2O3 and perovskite, and poor crystal quality of perovskite. In this work, we have engineered the interfaces throughout the entire solar cell via incorporating N, S co-doped graphene quantum dots (NSGQDs). The NSGQDs played remarkably multifunctional roles: i) facilitated the perovskite crystal growth; ii) eased charge extraction at both anode and cathode interfaces; iii) induced the defect passivation and suppressed the charge recombination. When assembled with a IH.(cid:8)2O3 ETL, the planar PSCs exhibited a significantly increased efficiency from 14% to 19.2%, with concomitant reductions in hysteresis, which created a new record of PCE for Fe2O3-based PSCs to date. In addition, PSCs with the entire device interfacial engineering showed an obviously improved durability, including prominent humidity, UV light and thermal-stabilities. Our interfacial engineering methodology via graphene quantum dots represents a versatile and effective way for building high efficiency as well as durability PSCs.
关键词： stability,Perovskite solar cells,interface engineering,PCE,graphene quantum dots,Fe2O3
更新于2025-09-23 15:19:57
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Influence of Precursor Concentration on Structural, Morphological and Optical Properties of Hematite (α-Fe <sub/>2</sub> O <sub/>3</sub> ) Nanoparticles
摘要： Background: We report for the first time that there is a considerable effect on the morphology and optical properties of hematite (α-Fe2O3) nanoparticles by varying the precursor concentrations from 1mmol to 3mmol. The nanoparticles were synthesized by combustion route using ferric nitrate, citric acid and ammonia as precursors at an annealing temperature range of 6000C. Phase purity, morphological studies and optical properties of the products were studied by powder X-ray diffraction (XRD), Field emission scanning electron microscopy (FESEM), Raman spectroscopy and UV Visible spectroscopy. The as-synthesized hematite nanoparticles have a mesoporous granular and somewhat spherical structure with a bulk density ranging from 0.11 to 0.59gmcm-3. Conclusion: The band gap of the as-synthesized α-Fe2O3 nanoparticles decreases from 1.96eV-1.77eV with the decrease in the precursor concentration. Raman spectroscopy confirmed the formation of a hematite phase of iron oxide nanoparticles. Practical percentage yield of the products increased from 47% to 65% with decrease in precursor concentrations.
关键词： α-Fe2O3 nanoparticles,band gap,Optical properties,morphological studies,bulk density,Combustion synthesis
更新于2025-09-23 15:19:57
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On the Theoretical and Experimental Control of Defect Chemistry, Electrical and Photoelectrochemical Properties of Hematite Nanostructures
摘要： Hematite (α-Fe2O3) is regarded as one of the most promising cost-effective and stable anode materials in photoelectrochemical applications, and its performance, like other transition metal oxides, depends strongly on its electrical and defect properties. In this work, the electrical and thermo-mechanical properties of undoped and Sn-doped α-Fe2O3 nanoscale powders were characterized in-situ under controlled temperatures (T = 250 to 400oC) and atmospheres (pO2 = 10-4 to 1 atm O2) to investigate their transport and defect properties. Frequency-dependent complex impedance spectra show that interfacial resistance between particles is negligible in comparison with particle resistance. Detailed defect models predicting the dependence of electron, hole, iron and oxygen vacancy concentrations on temperature and oxygen partial pressures for undoped and doped α-Fe2O3 were derived. Using these defect equilibria models, the operative defect regimes were established and the bandgap energy of undoped α-Fe2O3 and oxidation enthalpy of Sn-doped α-Fe2O3 were obtained from the analysis of the temperature and pO2 dependence of the electrical conductivity. Based on these results, we are able to explain the surprisingly weak impact of donor doping on the electrical conductivity of α-Fe2O3. Furthermore, experimental means based on the results of this study are given for successfully tuning hematite to enhance its photocatalytic activity for the water oxidation reaction.
关键词： dilatometry,α-Fe2O3,defect chemistry,photoelectrochemistry,electrical conductivity
更新于2025-09-23 15:19:57
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<i>In situ</i> growth of α-Fe <sub/>2</sub> O <sub/>3</sub> @Co <sub/>3</sub> O <sub/>4</sub> core–shell wormlike nanoarrays for a highly efficient photoelectrochemical water oxidation reaction
摘要： Photoelectrochemical (PEC) water splitting represents a promising strategy to convert solar energy into chemical energy in the form of hydrogen, but its performance is severely limited by the sluggish water oxidation reaction. Herein, for the first time, we report the direct assembly of an ultrathin, uniform, and dense layer of Co3O4 on wormlike nanostructured hematite (WN-α-Fe2O3) to form a large-area and high-density WN-α-Fe2O3@Co3O4 core–shell nanoarray via in situ hydrothermal growth followed by calcination, in which the electrostatic force between WN-α-Fe2O3 and the reactants, pH- and temperature-controlled structures of WN-α-Fe2O3, and ultralow nucleation rate of Co3O4 precursors all play critical roles. The obtained heteronanostructure array shows a photocurrent density of 3.48 mA cm?2, which is 4.05 times higher than that of pristine WN-α-Fe2O3 (0.86 mA cm?2), an onset potential of ～0.62 V, 60 mV lower than that of α-Fe2O3 (～0.68 V), and a photoconversion efficiency of 0.55%, 3.93 times higher than that of WN-α-Fe2O3 (0.14%). This is among the highest performances reported for Fe2O3-based photoanodes for water splitting. It is discovered that the Co3O4 shells can significantly enhance the charge separation, accelerate the charge transport and transfer, and reduce the charge transfer resistance from the photoelectrode to the electrolyte for a fast water oxidation reaction, thereby greatly promoting the PEC water oxidation performance of pristine WN-α-Fe2O3. This work not only creates a novel low-cost and Earth-abundant WN-α-Fe2O3@Co3O4 photoelectrode with superior PEC water oxidation performance and provides scientific insights into the enhancement mechanism, but also offers a general strategy for the in situ growth of water oxidation catalysts on various photoelectrodes with 3-D complex geometries for PEC water splitting.
关键词： α-Fe2O3,water oxidation reaction,Co3O4,Photoelectrochemical water splitting,core–shell nanoarray
更新于2025-09-23 15:19:57
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[BestMasters] Topographic Organization of the Pectine Neuropils in Scorpions (An Analysis of Chemosensory Afferents and the Projection Pattern in the Central Nervous System) || High Performance VOCs Sensor Based on ?-Fe2O3/Al-ZnO Nanocomposites
摘要： In this study, ternary G-Fe2O3/Al-ZnO nanocomposites (NC) were prepared using the solvothermal sol-gel process and a successive supercritical drying in ethanol. SEM analysis of the ternary NC samples showed clearly that they are formed by very small nanoparticles in the nanometer range. XRD highlighted the presence of the characteristic diffraction peaks of G-Fe2O3 and ZnO phases in all samples. Conductometric sensors were fabricated and tested for the monitoring of acetone in air. Results obtained have demonstrated that the ternary composite-based sensors display higher response to acetone and ethanol compared to that obtained with Al-ZnO and G-Fe2O3 ones.
关键词： Sol-gel,Acetone Selectivity,G-Fe2O3,Al-ZnO,Composite nanoparticles
更新于2025-09-19 17:15:36
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Hematite films by aerosol pyrolysis: influence of substrate and photocorrosion suppression by TiO2 capping
摘要： Sn-doped hematite (Fe2O3) films were prepared by aerosol pyrolysis (AP) on fluorine doped tin oxide (FTO), titanium and stainless steel. Photoactive electrodes were obtained in all cases and the photosensitivity had an onset around 650 nm. Maximum incident photon to electron conversion efficiency (IPCE) was 0.3 at 300 nm for samples deposited on FTO. The Faradaic efficiency of the photocorrosion reaction was found to be 0.47 % for an unprotected FTO/hematite electrode in H2SO4. The Faradaic efficiency of this dissolution reaction decreased to 0.3 % for a hematite electrode covered with a 65 nm thick dip coated layer of TiO2, and to 0.17 % for a sample with a spray coated TiO2 layer, thus proving the beneficial role of TiO2 in protecting hematite against photocorrosion.
关键词： photocorrosion,aerosol pyrolysis,α-Fe2O3 / TiO2 electrodes
更新于2025-09-19 17:15:36