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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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Highly Efficient Photoelectrochemical Water Splitting: Surface Modification of Cobalt-Phosphate-Loaded Co <sub/>3</sub> O <sub/>4</sub> /Fe <sub/>2</sub> O <sub/>3</sub> p-n Heterojunction Nanorod Arrays
摘要： Hematite (α-Fe2O3) as a photoanode material for photoelectrochemical (PEC) water splitting suffers from the two problems of poor charge separation and slow water oxidation kinetics. The construction of p–n junction nanostructures by coupling of highly stable Co3O4 in aqueous alkaline environment to Fe2O3 nanorod arrays with delicate energy band positions may be a challenging strategy for efficient PEC water oxidation. It is demonstrated that the designed p-Co3O4/n-Fe2O3 junction exhibits superior photocurrent density, fast water oxidation kinetics, and remarkable charge injection and bulk separation efficiency (ηinj and ηsep), attributing to the high catalytic behavior of Co3O4 for the oxygen evolution reaction as well as the induced interfacial electric field that facilitates separation and transportation of charge carriers. In addition, a cocatalyst of cobalt phosphate (Co-Pi) is introduced, which brings the PEC performance to a high level. The resultant Co-Pi/Co3O4/Ti:Fe2O3 photoanode shows a photocurrent density of 2.7 mA cm?2 at 1.23 VRHE (V vs reversible hydrogen electrode), 125% higher than that of the Ti:Fe2O3 photoanode. The optimized ηinj and ηsep of 91.6 and 23.0% at 1.23 VRHE are achieved on Co-Pi/Co3O4/Ti:Fe2O3, respectively, corresponding to the 70 and 43% improvements compared with those of Ti:Fe2O3. Furthermore, Co-Pi/Co3O4/Ti:Fe2O3 shows a low onset potential of 0.64 VRHE and long-time PEC stability.
关键词： photoanode,Co3O4,Fe2O3,p–n heterojunctions,Co-Pi
更新于2025-09-19 17:15:36
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Tailoring the surface morphology and nanoparticle distribution of laser-induced graphene/Co3O4 for high-performance flexible microsupercapacitors
摘要： Recent trends have witnessed laser induced graphene (LIG) syntheses on various materials from synthetic polymers to natural precursors. Herein, porcine skin derived gelatin was used as a medium to modify the surface morphology and nanoparticle distribution of in situ synthesized Co3O4/LIG on polyimide (PI) film. By varying the applied laser fluence, the surface morphology of LIG transitions from a 3D porous structure to a multilayered structure, Co3O4 progressively distributes from the surface to the inside of the LIG structure, and the structure changes from a sphere to a whisker-like shape. These altered attributes contribute to distinct differences in the double layer capacitance and pseudocapacitance behaviors of Co3O4/LIG, as reflected in its associated electrochemical performance. Additionally, a facile fabrication strategy including simple casting and peeling steps was used to generate stretchable microsupercapacitors (MSCs) on a waterborne polyurethane (WPU) substrate. The as-prepared stretchable MSCs present outstanding areal capacitance and excellent mechanical flexibility, whereas their electrochemical differences are significantly minimized and dominated by their inner structures.
关键词： Co3O4,morphology transition,supercapacitor,laser-induced graphene,gelatin
更新于2025-09-12 10:27:22
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Carbon supported oxygen vacancy-rich Co3O4 for robust photocatalytic H2O2 production via coupled water oxidation and oxygen reduction reaction
摘要： Photocatalytic H2O2 production is a promising strategy to alleviate energy crisis since H2O2 is an important liquidus chemical and fuel. However, the following problems severely restrict the development of this technique: (1) low selectivity; (2) low stability (normally less than 5 short-time cycles); (3) fast charge recombination; (4) assistance of hole scavengers and (5) demand of O2 saturation. Herein, carbon supported oxygen vacancy-rich Co3O4 nanoplate (C-ovCo) is reported as an efficient photocatalyst for scavenger-free H2O2 production by coupled 2e– water oxidation (WOR) and 2e? oxygen reduction reaction (ORR) with low energy barrier of 1.1 eV. In this system, the oxygen vacancies can reduce the band gap, enhance the donor density, improve the charge separation and migration and work as WOR sites, while the carbon support accepts electrons and works as ORR sites. The photocatalysts exhibit an optimal H2O2 production rate of 3.78 mmol h–1 g–1 under visible light (λ ≥ 420 nm), an apparent quantum efficiency (AQE) of 16.7% at 420 nm, and a solar-to-chemical efficiency (SCC) of 0.4%. Moreover, the stability of over 720 h (30 long-time cycles) is also superior to the state-of-the-art photocatalytic systems.
关键词： Carbon supported oxygen vacancy-rich Co3O4,Coupled reaction,Photocatalytic H2O2 production,Oxygen reduction reaction,Water oxidation reaction
更新于2025-09-11 14:15:04
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Co3O4/TiO2 hetero-structure for methyl orange dye degradation
摘要： Advanced oxidation processes based on sulphate radical generated by peroxymonosulphate (PMS) activation is a promising area for environmental remediation. One of the biggest drawbacks of heterogeneous PMS activation is catalyst instability and metal ion leaching. In this study, a simple organic binder mediated route was explored to substitute Ti4t ions into the Co3O4 host lattice structure to create a Co-O-Ti bond to minimise cobalt leaching during methyl orange degradation. The catalyst was characterised by X-ray diffraction, and scanning and transmission electron microscopy. The as-prepared catalysts with Co3O4:TiO2 ratio of 70:30 exhibited minimal leaching (0.9 mg/L) compared to other ratios studied. However, the pristine Co3O4 exhibited highest catalytic activity (rate constant ? 0.41 min(cid:2)1) and leaching (26.7 mg/L) compared to composite material (70:30 Co3O4:TiO2). Interestingly, the morphology of the composite and leaching of Co2t ions were found to be temperature dependent, as an optimum temperature ensured strong Co-O-Ti bond for prevention of Co2t leaching. The classical quenching test was utilised to determine the presence and role of radical species on methyl orange degradation. The fabricated catalyst also exhibited good catalytic activity in degrading mixed dyes and good recyclability, making it a potential candidate for commercial application.
关键词： advanced oxidation processes (AOPs),leaching,TiO2,heterogeneous reaction,Co3O4,PMS
更新于2025-09-10 09:29:36
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Dual Fabry–Pérot Interferometric Carbon Monoxide Sensor Based on the PANI/Co3O4 Sensitive Membrane-Coated Fibre Tip
摘要： A novel dual Fabry–Pérot (F-P) interferometric carbon monoxide gas sensor based on polyaniline/Co3O4 (PANI/Co3O4) sensing film coated on the optical fibre end face is proposed and fabricated. Its structure is composed of standard single-mode-fibre (SMF), endlessly photonic crystal fibre (EPCF), and PANI/Co3O4 sensing membrane (PCSM). Therefore, they form three F-P reflectors, the reflector between SMF and EPCF, that between EPCF and PCSM, and interface between PCSM and air. So, the dual F-P interferometer is achieved. The results show that in the range of 0–70 ppm, the interference spectra appear red shift with the increasing carbon monoxide concentration. In addition, the high sensitivity of 21.61 pm/ppm, the excellent linear relationship 2 = 0.98476), and high selectivity for carbon monoxide (R are achieved. The response and recovery time are 35 and 84 s, respectively. The sensor has the advantages of high sensitivity, strong selectivity, low cost, and simple structure and is suitable for sensitive detection of trace carbon monoxide gas.
关键词： Photonic Crystal Fibre,Polyaniline,Dual Fabry–Pérot Interferometer,Co3O4,Gas Sensor,Carbon Monoxide
更新于2025-09-09 09:28:46
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Petal-biotemplated synthesis of two-dimensional Co3O4 nanosheets as photocatalyst with enhanced photocatalytic activity
摘要： A biomorphic Co3O4 nanosheet was fabricated by using China rose petal as biotemplate. Ultraviolet-visible diffuse reflectance spectroscopy, nitrogen adsorption, Fourier-transform infrared spectroscopy, thermogravimetric analysis-differential scanning calorimetric analysis, scanning electron microscopy, transmission electron microscopy and powder X-ray diffraction were utilized to characterize the samples. The results revealed that the synthesized Co3O4 sample exhibited the special 2D nanosheet morphology with the thickness of around 100 nm similar to the original petal. The 2D nanosheet structure and multiple-porous feature of the sample not only increased its specific surface area and more active sites for photodegradation reaction, but also facilitated mass transfer, light scattering and harvesting as well as inhibition of the photogenerated carrier recombination. Moreover, compared with the commercial Co3O4, the as-prepared Co3O4 nanosheet showed a superior photocatalytic activity due to its 2D multiple-porous nanosheet structure and high specific surface area (51.36 m2 g?1).
关键词： Petal,Biotemplate,Co3O4 nanosheet,Photocatalysis,Multiple-porous structure
更新于2025-09-09 09:28:46
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A specifically-exposed cobalt oxide/carbon nitride 2D heterostructure for carbon dioxide photoreduction
摘要： Photocatalytic reduction of CO2 provides an opportunity to reach carbon neutrality, by which CO2 emissions from fuel consumption can be converted back to fuels. The challenge is to explore materials with high charge separation efficiency and effective CO2 adsorption capacity to boost the photoreduction of CO2. Here we report that 2D heterostructure comprised of Co3O4/2D g-C3N4 (COCN) can provide enhanced photocatalytic performance of reducing CO2 to CO, yielding a CO production rate of 419 μmol g-1 h-1 with selectivity of 89.4%, which is 13.5 and 2.6 times higher than that of pure 2D g-C3N4 and Co3O4. The enhanced photocatalytic performance arises from: (i) enhanced light absorption ability and charge separation efficiency originated from the unique 2D heterostructure connected through specifically-exposed facet interface and (ii) favorable CO2 adsorption capacity. The study may provide insight for the establishment of heterostructure-based photocatalytic system toward CO2 reduction.
关键词： g-C3N4,Co3O4,Composite photocatalysts,CO2 conversion
更新于2025-09-04 15:30:14
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MOFs-derived ultrathin holey Co3O4 nanosheets for enhanced visible light CO2 reduction
摘要： Reducing carbon dioxide (CO2) to various value-added chemical products by photocatalysis could effectively alleviate the serious problems of global warming and energy shortages. Currently, most commonly prepared photocatalysts present poor performance under visible light irradiation. In this study, we adopted a facile, scalable and controllable approach to prepare ultrathin two-dimensional (2D) porous Co3O4 catalysts (Co3O4-NS) by air calcining of the ultrathin metal-organic framework (MOFs) nanosheet templates to validly reduce CO2 with a Ru-based photosensitizer under visible light irradiation. Benefitting from the structural nature of MOFs precursors, the calcined Co3O4-NS inherit the morphology of 2D and well-developed porosity, which support the transport of electrons, enhance the adsorption of CO2 molecules, and render abundant catalytic sites for CO2 activation. As a result, the CO generation rate is approximately 4.52 μmol·h-1 with selectivity of 70.1%, which is superior to the Co3O4 bulk catalysts (Co3O4-BK). Additionally, density functional theory (DFT) calculations reveal that the model of Co3O4 monolayer has stronger CO2 adsorption energy than that of the Co3O4 bulk, which is beneficial for the CO2-to-CO conversion. This MOF-engaged strategy provides new insight into the controlled synthesis of advanced ultrathin holey nanosheets to improve the efficiency of photocatalytic CO2 reduction.
关键词： ultrathin nanosheets,Co3O4,photocatalysis,MOFs derived,CO2 reduction
更新于2025-09-04 15:30:14
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Co <sub/>3</sub> O <sub/>4</sub> nanoparticles decorated Ag <sub/>3</sub> PO <sub/>4</sub> as heterostructure for improving solar-light-driven photocatalysis
摘要： As a common photocatalytic material, Ag3PO4 still faces the challenge including the fast recombination of photo-generated electron-hole (e--h+) pairs. In this work, we prepared Co3O4/Ag3PO4 heterojunction with good optical properties by an in-situ precipitation method. Compared to pure Ag3PO4, the Co3O4/Ag3PO4 exhibited greatly improved photocatalytic activities for degradation methylene blue (MB) and bisphenol A (BPA) under the visible light irradiation. Here, the degradation rate of MB could reach up to 12% which is about 35% higher than that of pure Ag3PO4, after 18 min irradiation. The degradation rate of BPA could reach up to 33% which is about 45% higher than the pure Ag3PO4. This work may provide insight for finding a new Ag3PO4 photocatalyst for promoting the photocatalytic performance
关键词： solar-light-driven,degradation,heterostructure,Co3O4/Ag3PO4,photocatalysis
更新于2025-09-04 15:30:14