ZnO nanorods (NRs) are promising components in a wide range of nanoscale devices for future applications in photocatalysis, solar cells, optical devices and biochemical sensing. The nanorods in the ...form of arrays vertically oriented to the substrate may be obtained by electrochemical deposition but morphology of the film is very sensitive to the synthesis conditions. This article provides a comprehensive review on various electrosynthesis procedures developed to obtain the nanorods of desired structure, diameter, density on the substrate.
We discuss the growth mechanisms and influence of different parameters such as the type and concentration of Zn2+ and OH− precursors, the value of applied potential or current density on the morphology of obtained ZnO films and the role of various structural modifiers on the shape of ZnO nanostructures. We present a brief analysis of the influence of electrosynthesis conditions and postannealing of the samples on optical and electrical properties of ZnO nanowires deposited on the conducting substrate. A short summary of the practical applications of ZnO nanorods is also provided.
This paper reports the synthesis and characterization of an efficient sunlight active photocatalyst, i.e. α-Bi2O3 nanorods for the photocatalytic degradation of Rhodamine B and 2,4,6-trichlorophenol. ...The α-Bi2O3 nanorods were synthesized by a simple surfactant free sono-chemical route at ambient conditions and characterized in detail in terms of their morphological, structural, compositional and optical properties. The detailed characterizations revealed that the prepared nanorods exhibited high purity, well-crystalline monoclinic α-Bi2O3 structure and excellent optical properties. The catalytic behaviour of α-Bi2O3 was investigated for the degradation of a cationic dye (Rhodamine B), its simulated dye bath effluent and 2,4,6-trichlorophenol under solar light irradiation. The as-synthesized α-Bi2O3 nanorods catalyst exhibited excellent solar-light driven photocatalysis towards Rhodamine B (97% dye degradation in 45min) and 2,4,6-trichlorophenol (88% dye degradation in 180min). The presented results demonstrate that α-Bi2O3 nanorods are excellent solar-light driven photocatalyst for the photocatalyst degradation of organic dyes and pollutants.
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•The tree-branch-like Fe2P@NixP/NF nanoarrays architecture was constructed.•Simultaneousenhancementoftheelectronandmasstransportcanberealized.•The Fe2P@NixP/NF electrode exhibits ...superior electrocatalytic HER and UOR activity.
It’s highly desirable but still challenging, through the structure construction strategy, to design brilliant bifunctional electrocatalysts for the urea oxidation reaction (UOR) and hydrogen evolution reaction (HER) with both fast electron and mass transport, especially under high current densities. Herein, a novel tree-branch-like Fe2P@NixP heterostructure nanoarrays on NF (denoted as Fe2P@NixP/NF) were fabricated as bifunctional catalysts to realize urea-rich-water electrolysis at large current density. Benefiting from the tree-branch-like hierarchical architectures with rich exposed heterointerfaces between Fe2P and NixP that can simultaneously achieve facilitated mass and electron transfer, the elaborated Fe2P@NixP/NF electrode shows brilliant electrocatalytic UOR and HER performance. The assembled Fe2P@NixP/NF|| Fe2P@NixP/NF couple could yield the current density of as high as 500 mA cm−2 at super low cell voltage of 1.604 V for urea electrolysis. We believe our work can chart a brand-new-path in developing an industrial electrolyzer to promise an energy-saving H2 generation along with urea-rich wastewater treatment.
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•Successfully synthesized Fe3O4 nanorods coated PPy/rGO by chemical reflux method.•Fe3O4@PPy/rGO/GCE effectively sensing dopamine molecules.•Fe3O4@PPy/rGO/GCE shows better ...repeatability, reproducibility and stability.•Photocatalytic studies reveal 84% ACP degradation by Fe3O4@PPy/rGO with persulfate.•ACP photodegradation studies shows rate constant of 9.13 × 10−4 M−1 s−1.
The increase in the world’s population has exerted tremendous pressure on the research community to solve the related health and environmental issues. Hence, it is an important and challenging task to design a multifunctional catalyst that both aids medical diagnostics and removes organic pollutants from aqueous environments. Herein, we developed iron oxide nanorods uniformly coated on the polypyrrole/reduced graphene oxide (Fe3O4@PPy/rGO) nanohybrids by the chemical reflux method. The optimized Fe3O4@PPy/rGO nanohybrids show better electrochemical detection of dopamine (DA) with a low detection limit (0.063 µM) and a better linearity range (0 to 100 µM), with a coefficient of determination of 0.994. The Fe3O4@PPy/rGO nanohybrids reveal an excellent DA recovery rate of 97– 98% during real sample analysis. In addition, photocatalytic studies reveal that 84% acetaminophen (ACP) degradation by Fe3O4@PPy/rGO nanohybrids was noticed with the persulfate. The effect of co-existing photocatalytic studies affirms that the higher ACP photodegradation rate constant of 9.13 × 10−4 M−1 s−1 was obtained in the presence of the Cl− ion. The present work provides a new pathway for the development of a metal oxide with a conducting polymer and graphene-based catalyst for multi-functional applications for the electrochemical sensing and photodegradation of organic pollutants.
By introducing MoO2–C nanomaterials into Mn0·2Cd0·8S nanorods, the S-scheme heterojunction of MoO2–C/Mn0·2Cd0·8S with unique interface microstructure was successfully constructed. It is worth ...mentioning that there is a disorder region in MoO2–C nanocomposites, which provides the main active center for photocatalytic decomposition of water. Photoelectrochemical tests show that the existence of S-scheme heterojunction and carbon rod leads to the rapid separation of charge and the effectively decrease of hydrogen evolution potential. S-scheme heterojunction can promote the charge separation and transfer between MoO2–C and Mn0·2Cd0·8S quickly and effectively. Compared with pure Mn0·2Cd0·8S, MOCMCS has high hydrogen evolution activity, and its activity is about 13 times higher. The significant improvement of photocatalytic performance is due to the existence of S-scheme heterostructure between MoO2–C/MCS and small transfer resistance, coupled with the excellent conductivity of carbon rods, which effectively promote the charge separation and transfer between MoO2–C and Mn0·2Cd0·8S nanorods.
•There is a disorder zone on the interface between carbon material and MoO2 crystal plane.•S-scheme heterojunction composed of MoO2–C and Mn0·2Cd0·8S was formed.•The presence of carbon rods greatly inhibits the recombination of photogenerated electron-hole pairs.
Sodium ion batteries (SIBs) are a promising replacement for the widely prevalent Li-ion batteries (LIBs) as an efficient energy storage technology. Development of electrode materials with high energy ...density and high power density is the key to achieving high performance SIBs. Here, we demonstrate a high-capacity and high-rate SIB cathode which is made of one-dimensional FeS2 nanorods, where an extrinsic pseudocapacitance contribution is found and verified by cyclic voltammetry. The carbon coated FeS2 nanorods exhibit ultra-long lifespan (9000 cycles), high reversible capacity (506.9 mAh g−1 at 500 mA g−1), and outstanding rate capability (140 mAh g−1 at 20 A g−1).
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•A facile approach is proposed to fabricate FeS2@C nanorods for sodium ion battery.•The FeS2@C deliverers ultra-long cycling stability and notable rate performance.•Pseudocapacitance behavior of FeS2@C in SIBs was analyzed and quantified.
Nitrogen-vacancy crystalline g-C3N4 nanosheets with tunable band structures were successfully prepared by alkali-molten salt-assisted method. The excellent and stable photocatalytic overall water ...splitting activity with H2 and O2 evolution rate of 49.60 μmol g−1 h−1 and 24.71 μmol g−1 h−1 was obtained over g-C3N4-D2 which loaded Pt and Co3O4 nanorods as cocatalysts (Pt/g-C3N4-D2/3%Co3O4 NRs) under AM 1.5G simulated light irradiation. In the half-reaction experiments, the maximum H2 evolution rate of Pt/g-C3N4-D2/3%Co3O4 NRs is 3.78 mmol g−1 h−1 with a notable quantum efficiency of 11.94% at 400 nm, and the solar-hydrogen conversion efficiency (STH) is 1.48%.
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•Nitrogen-vacancy crystalline g-C3N4 was prepared via molten-salt-assisted method.•Vacancy and highly-crystalline can efficiently promote charge separation.•Matching of HER/OER via Pt and Co3O4 NRs further improve charge carrier separation.•g-C3N4-D2/3%Co3O4 has high H2 evolution rate with marked AQE (11.94 %) and STH (1.48 %).•Pt/g-C3N4-D2/3%Co3O4 possesses outstanding overall water splitting activity.
The photocatalytic overall water splitting performance of graphitic carbon nitride (g-C3N4) has still been restricted by its inefficient charge separation efficiency. Herein, nitrogen-vacancy crystalline g-C3N4 nanosheets (g-C3N4-D) with tunable band structures were successfully prepared by the alkali-molten salt-assisted method for efficient photocatalytic overall water splitting. Among them, g-C3N4-D2 not only combines the advantages of the amorphous and crystalline state of two-dimensional g-C3N4 nanosheets, but also introduces nitrogen vacancy to adjust the bandgap structures of crystalline g-C3N4 by an alkali etching, thus improving the light energy utilization and charge separation efficiency. TEM and EPR spectrum prove the existence of N defects in the crystalline g-C3N4. The excellent and stable photocatalytic overall water splitting activity with H2 and O2 evolution rate of 49.60 μmol g−1 h−1 and 24.71 μmol g−1 h−1 was obtained over g-C3N4-D2 with Pt and Co3O4 nanorods as cocatalysts (Pt/g-C3N4-D2/3%Co3O4 NRs) under AM 1.5G simulated light irradiation. In the half-reaction experiments, the maximum H2 evolution rate of Pt/g-C3N4-D2/3%Co3O4 NRs is 3.78 mmol g−1 h−1 with a significant quantum efficiency of 11.94 % at 400 nm, and the solar-hydrogen conversion efficiency (STH) is 1.48 %. The photocatalytic water oxidation activity of Pt/g-C3N4-D2/5%Co3O4 NRs is 42.34 μmol g−1 h−1. Additionally, the potential mechanism of photocatalytic overall water splitting was testified by in-situ XPS. This work provides a simple strategy for further advancing the potential application of g-C3N4 by molten salt-assisted alkali etching to introduce N vacancies to regulate the band gap of crystalline g-C3N4 for photocatalytic overall water splitting.
In this work, we report the synthesis of TiO2 (core)/MnO2(shell) nanorods by a redox reaction and TiO2 nanorods generated in-site from H-titanate nanorods during hydrothermal process. The MnO2 ...nanoflakes were grown densely on TiO2 nanorods to form core-shell nanorods. Owing to the strong TiO2-MnO2 interfacial interaction and enriched oxygen vacancies, TiO2/MnO2 nanorods are highly active and stable as capacitive electrodes. The quantitative analysis of XPS shows more oxygen vacancies were generated in the TiO2/MnO2 materials. The specific capacitance of TiO2/MnO2 is 368.9 F/g, more than double of 140.8 F/g on the MnO2 materials. At 1.5 A/g, 92% of the initial capacitance of the TiO2/MnO2 was still retained after 3000 charge-discharge cycles. However, the specific capacitance on the pure MnO2 materials lost 39% after 3000 cycles. Our results suggest that the improved capacitive properties of TiO2/MnO2 are closely related to enriched oxygen vacancies, unique structure, higher surface area, as well as interfacial interaction between TiO2 and MnO2.
•MnO2 nanoflaks (shell) was grown successfully on TiO2 (core) nanorods as core-shell materials for supercapacitor.•Quantitative XPS analysis shows more Mn3+ ions and more oxygen vacancies were generated on the materials.•High surface area was achieved on TiO2/MnO2 nanorods.•The materials show better capacitance and improved cycling stability.
Herein, BiFeO3 nanorods (BFO NRs) was synthesized as the piezoelectric catalyst. The synergistic mechanism of sonolysis and sono-induced BFO-piezocatalysis in atenolol degradation was revealed and ...the effect of ultrasonic parameters on it was investigated for the first time. The results indicated that 100 kHz was the optimal frequency for the sonolytic and sono-piezocatalytic degradation of atenolol in ultrasound/BFO nanorods (US/BFO NRs) system, with the highest synergistic coefficient of 3.43. The piezoelectric potential differences of BFO NRs by COMSOL Multiphysics simulations further distinguishing that the impact of cavitation shock wave and ultrasonic vibration from sonochemistry reaction (i.e., 2.48, −2.48 and 6.60 V versus 0.008, −0.008 and 0.02 V under tensile, compressive and shear stress at 100 kHz). The latter piezoelectric potentials were insufficient for reactive-oxygen-species (ROS) generation, while the former contributed to 53.93% •OH yield in US/BFO NRs system. Sono-piezocatalysis was found more sensitive to ultrasonic power density than sonolysis. The quenching experiments and ESR tests indicated that the ROS contribution in atenolol degradation followed the order of •OH > 1O2 > h+ > O2•- in US/BFO NRs system and 1O2 generation is exclusively dissolved-oxygen dependent. Four degradation pathways for atenolol in US/BFO NRs system were proposed via products identification and DFT calculation. Toxicity assessment by ECOSAR suggested the toxicity of the degradation products could be controlled.
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•The effect of ultrasonic parameters on synergistic mechanism was investigated for the first time.•COMSOL simulation indicated sono-piezocatalysis is excited by sono-cavitation rather than sono-vibration.•Atenolol degradation-pathways were deduced by DFT calculations.
