Low-temperature Chemical Method Research Articles

Influence of phase transition with annealing temperature on structural, morphological, and supercapacitive characteristics of molybdenum oxide nanostructures

In this study, molybdenum oxide nanostructures (MoO3 NSs) were effectively synthesized through a simple, low-cost, surfactant-free, low-temperature, and scalable chemical co-precipitation method and investigated their synergistic effect with annealing temperature on energy storage applications for the first time. Herein, we have reported a phase transition of MoO3 NSs from hexagonal to orthorhombic after the annealing temperature varied from 100°C to 500°C at constant time. Additionally, the resultant NSs were thoroughly examined for their physio-chemical characteristics, which revealed the stable phase formation of the MoO3 NSs, respectively. Furthermore, the electroactive MoO3 NSs were pasted on Ni-foam substrate (M@NF), and electrochemical properties were evaluated using a three-electrode setup at room-air temperature in 1M KOH aqueous electrolyte across the potential range of 0V to 0.786V. As a result, the M@NF-5 electrode exhibited an impressive specific capacitance of 976.84Fg-1 at a scan rate of 1 Mv s-1, a higher energy density of 73.69Whkg-1, and a power density of 655Wkg-1 at 5mAg-1. The non-linear galvanostatic charge-discharge (GCD) profile aligns well with the cyclic voltammetry (CV) analysis. Both CV and GCD techniques confirm the pseudocapacitive behavior, with 83% capacitive retention observed after 2000 cycles. The fabricated symmetric device (M@NF-5//M@NF-5) exhibits enhanced electrochemical performance with a specific capacitance of 67.35Fg-1 at 5mAg-1 and with an energy density of 18Whkg-1, and a power density of 1750Wkg-1 at a specific current. These findings underscore the potential of chemically deposited α-MoO3 as an auspicious material for use in supercapacitor applications.

The GeSe/SnSe heterojunction photodetector with self-powered characteristics and high infrared response performance

We present a GeSe/SnSe van der Waals heterojunction fabricated using the wet transfer technique. GeSe and SnSe were synthesized via a low-temperature and atmospheric-pressure chemical vapor deposition method. The GeSe/SnSe heterostructure photodetector demonstrates remarkable rectification characteristics, boasting a rectification ratio of 102, along with an exceptionally low dark current, indicating minimal power consumption. Furthermore, it exhibits a broad optical response, spanning from the visible spectrum (450 nm) to the near-infrared (1064 nm). Under 808 nm laser illumination and reverse bias, the device achieves a responsivity of 19.82 A/W, a detectivity of 4.74 × 109 Jones, and an external quantum efficiency of 3048.32%. Notably, the GeSe/SnSe heterojunction photodetector also exhibits self-powered characteristics, with a responsivity of 0.11 mA/W and a detectivity of 5.44 × 106 Jones at zero bias voltage, accompanied by a fast response time of 23/61 ms (rise/fall). These findings underscore the effectiveness of the GeSe/SnSe heterojunction as a strategy for near-infrared photodetectors to simultaneously achieve low power consumption, high photoresponsivity, and self-powered photodetection, which is promising for optoelectronic device applications.

High-Entropy Alloy Al0.2Co1.5CrFeNi1.5Ti0.5 Prepared from High-Entropy Oxide (Al0.2Co1.5CrFeNi1.5Ti0.5)3O4 by a Deoxidation Process via a CaH2-Assisted Molten Salt Method

High-entropy alloys (HEAs) have attracted a great deal of research interest these days because of their attractive properties. Low-temperature chemical synthesis methods are being developed to obtain nanoscale HEAs with low energy consumption. In this study, we prepared HEA Al0.2Co1.5CrFeNi1.5Ti0.5 nanoparticles from high-entropy oxide (HEO) (Al0.2Co1.5CrFeNi1.5Ti0.5)3O4 by a deoxidation process via a CaH2-assisted molten salt method at 600 °C. X-ray diffraction measurements demonstrated that the oxide precursor and the reduced product have single-phases of spinel structure and face-centered cubic structures, indicating the formation of HEO and HEA, respectively. The HEA nanoparticles exhibited superior catalytic performance in the liquid-phase hydrogenation of p-nitrophenol at room temperature with little leaching of the component elements. Scanning electron microscopy (SEM) with energy-dispersive X-ray spectrometry (EDX) exhibited a good distribution of constituent elements over the HEA nanoparticles in a micro-sized range. However, transmission electron microscopy (TEM) with EDX revealed a slight deviation of elemental distributions of Al and Ti from those of Co, Cr, Fe, and Ni in a nano-sized range, probably due to the incomplete reduction of aluminum and titanium oxides. The elemental homogeneity in the HEA nanoparticles could be improved by taking advantage of the HEO precursor with homogeneous elemental distributions, but the experimental results suggested the importance of the total reduction of oxide precursors to prepare homogeneous HEAs from HEOs.

Synthesis of nickel-copper layered double hydroxides for asymmetric supercapacitors by low-temperature chemical co-precipitation method

Synthesis of nickel-copper layered double hydroxides for asymmetric supercapacitors by low-temperature chemical co-precipitation method

Iron-doping-induced formation of Ni-Co-O nanotubes as efficient bifunctional electrodes.

The rational design of earth-abundant and efficient electrocatalysts to replace precious metal-based materials is highly anticipated for overall water splitting. Herein, NiCo2O4 electrocatalysts with different Fe doping amounts (Fex-NCO, x = 1, 2, 3) were synthesized by a low-temperature chemical method. It was interesting to find that the doping of Fe induced the formation of NiCo2O4 nanotube arrays by modulating the Fe content. The Fe3-NCO electrode with a nanotube structure and rich oxygen vacancies exhibited exceptional electrocatalytic activities for the hydrogen evolution reaction (97 mV, 10 mA cm-2) and oxygen evolution reaction (188.4 mV, 10 mA cm-2). DFT calculations revealed that Fe promoted the modulation of the electronic structure, which played a crucial role in optimizing the reaction intermediates and altered the energy level of the d band center, and as a result, enhanced the water dissociation ability. Additionally, a low cell voltage of 1.56 V (10 mA cm-2) was realized for water splitting based on an as-fabricated Fe-doped NiCo2O4 nanotube array bifunctional electrode.

Design of photocatalytic self-cleaning poly (arylene ether nitrile)/nitrogen-doped Bi2O2CO3 composite membrane for emulsified oily wastewater purification

Membrane separation technique offers unique advantages for treating the emulsified oily wastewater with the oil droplet diameter less than 20 µm. However, the complicated membrane fouling originating from oils and soluble matters pose the huge challenges to membrane separation technique, which has stimulated the development of advanced membrane materials. Herein, we reported the photocatalytic and super-wetting poly (arylene ether nitrile) (PEN) fibrous composite membrane with high permeability and enhanced anti-fouling ability. The nitrogen-doped Bi2O2CO3 (N-Bi2O2CO3) was prepared by low-temperature chemical modification method and modified by dopamine (DA)-polyethyleneimine (PEI), which was further self-assembled on porous PEN support backbone. The hydrophilicity provided by the cross-linking reaction between PDA and PEI and micro-/nano- rough surface constructed by the flower-like N-Bi2O2CO3 contributed to the super wetting properties (WCA=0°, UOCA>150°), which imparted the membrane with ultra-low oil adhesion. In particular, the arrangement of flower-like N-Bi2O2CO3 effectively regulated the water channel of membrane, further increasing the permeate flux. Therefore, the fibrous composite membranes showed superior separation flux (632.79–762.81 L·m−2·h−1) and separation efficiency (>99.16%) for various oil-in-water emulsions, even under harsh conditions (90 ℃ and 2 M NaCl solution). More importantly, the N-Bi2O2CO3 rendered the membrane excellent degradation rates for various dyes (MO: 95.53%, MeB: 96.40%, CV: 96.45%, CR: 87.14%), achieving favorable photocatalytic self-cleaning ability. This work opens an alternative strategy to fabricate fibrous composite membrane with synergistically enhanced anti-fouling for the treating complicated emulsified oily wastewater in petrochemical industry.

Low-temperature resin embedding of the whole brain for various precise structures dissection

Resin embedding combined with ultra-thin sectioning has been widely used in microscopic and electron imaging to acquire precise structural information of biological tissues. However, the existing embedding method was detrimental to quenchable fluorescent signals of precise structures and pH-insensitive fluorescent dyes. Here, we developed a low-temperature chemical polymerization method named HM20-T to maintain weak signals of various precise structures and to decrease background fluorescence. The fluorescence preservation ratio of green fluorescent protein (GFP) tagged presynaptic elements and tdTomato labeled axons doubled. The HM20-T method was suitable for a variety of fluorescent dyes, such as DyLight 488 conjugated Lycopersicon esculentum lectin. Moreover, the brains also retained immunoreactivity after embedding. In summary, the HM20-T method was suitable for the characterization of multi-color labeled precise structures, which would contribute to the acquisition of complete morphology of various biological tissues and to the investigation of composition and circuit connection in the whole brain.

A comparative photocatalytic degradation study of cationic and anionic dyes using ZnIn2S4 photocatalyst

Semiconductor mediated photocatalysis has emerged as a promising solution for dye degradation and environmental remediation. Zinc Indium Sulfide (ZnIn2S4, ZIS) is a benign, eco-friendly, visible-light-responsive photocatalyst, exhibiting excellent optoelectronic properties. In this work, we present a scalable, low temperature and template-free chemical aqueous solution method for the synthesis of ZIS. The obtained powder sample was used for a comparative dye degradation study of cationic (Malachite green) and anionic (Congo red) dye. The higher photocatalytic efficiency of ZIS is due to the higher BET surface area (55.042 m2 g−1) and low band gap (2.3 eV). Under Sunlight, almost 80 percent degradation occurs within 20 min of the experiment for both Malachite green (MG) and anionic Congo red (CR) dye, outperforming previously reported results. Scavenger studies were used to figure out the radicals involved in photocatalytic mechanics and to come up with viable photocatalytic degradation routes. The reusability and stability of ZIS were carried out up to the 5th cycles. Our result revealed that ZIS possesses high stability, reusability, and efficient potential to be an effective dye degradation photocatalyst.

Significant enhancement in the cold emission characteristics of chemically synthesized super-hydrophobic zinc oxide rods by nickel doping.

The current article presents a huge enhancement in the field emission characteristics of zinc oxide (ZnO) micro/nanorods by nickel doping. The synthesis of pure and nickel-doped zinc oxide (ZnO) micro/nanorods was done by a simple low-temperature chemical method. Both the as-prepared pure and doped samples were analyzed by X-ray diffraction and electron microscopy to confirm the proper phase formation and the developed microstructure. UV-vis transmittance spectra helped in determining the band gap of the samples. Fourier-Transform Infrared Spectroscopy (FTIR) spectra showed the different bonds present in the sample, whereas X-ray Photoelectron Spectroscopy (XPS) confirmed the presence of nickel in the doped sample. Photoluminescence (PL) spectra showed that after doping, the band-to-band transition was affected, whereas defect-induced transition had increased significantly. After the nickel doping, contact angle measurement revealed a significant decrease in the sample's surface energy, leading to a remarkably high water contact angle (within the superhydrophobic region). Simulation through ANSYS suggested that the doped sample has the potential to function as an efficient cold emitter, which was also verified experimentally. The cold emission characteristics of the doped sample showed a significant improvement, with the turn-on field (corresponding to J = 1 μA cm-2) reduced from 5.34 to 2.84 V μm-1. The enhancement factor for the doped sample reached 3426, approximately 1.5 times higher compared to pure ZnO. Efforts have been made to explain the results, given the favorable band bending as well as the increased number of effective emission sites.

The effect of surface modification with Ag nanoparticles on 21 nm TiO2: anatase/rutile material for application in photocatalysis

The purpose of this article is to present a perspective, environmentally friendly, and cost-effective chemical approach for preparing photocatalysts that can be used in wastewater treatment. One nanometer-sized Ag nanoparticles (NPs) were deposited on the surface of a commercial titanium dioxide mixture of anatase and rutile. A novel low-temperature chemical method using an ultrasonication process without a reducing agent was applied to surface-modified TiO2 grains with Ag NPs. The materials were characterized by several complementary techniques, such as X-ray powder diffraction (XRD), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), UV–Vis diffuse reflectance (DRS), Raman spectroscopy, X-ray electron spectroscopy (XPS), Mott-Schottky analysis, and N2 adsorption-desorption measurements. The silver content in the prepared samples ranged from 0.1 to 0.5 wt% (low Ag content) and from 1 to 5 wt% (high Ag content). The photocatalytic performance of the pristine and Ag NPs modified TiO2 powders in photodegradation of the acid orange 7 model dye was studied under ultraviolet (UV), visible (Vis) and UV + Vis radiation. This study explores, for the first time, a photodegradation mechanism for all combinations of wavelengths and silver contents, which is of practical importance in selecting the best photocatalyst and irradiation conditions.

Plasmonic and bi-piezoelectric enhanced photocatalysis using PVDF/ZnO/Au nanobrush

Abstract The photocatalytic degradation, as an environmental-friendly technology, has great significance for cost-effective and efficient catalysis processes, wherein piezo-photocatalysis can significantly increase the catalytic degradation rate using both solar and mechanical energy. Here, a ternary heterostructure PVDF/ZnO/Au (PZA) nanobrush photocatalyst with high piezo-photocatalytic efficiency was presented via low-temperature hydrothermal and chemical reduction methods. Under both solar and mechanical energy, the current response and degradation rate of the as-synthesized PZA nanobrush all increase significantly compared with that under solar alone and under mechanical energy alone, and the excellent recyclability is investigated. It is found that the PZA nanobrush with ultrasonic-assisted piezo-photocatalysis completely degrade MO of 20 mg/L in 60 min, which exhibits greater enhancement of photocatalytic activity than with stirring-assisted piezo-photocatalysis due to higher power. The high piezo-photocatalytic activity of PZA nanobrush is attributed to the surface plasmon resonance (SPR) coupling of Au and built-in electric field originating from the ZnO and PVDF, which can increase the absorption of visible light, promote the charge transfer and separation of photogenerated electrons/holes. This work introduces the SPR and bipiezotronic effect to improve plasmonic photocatalysis with PZA heterostructures, which offers a new solution in green technologies to design high-performance catalysts for the environmental remediation.

Ag2O@PANI nanocomposites for advanced functional applications: A sustainable experimental and theoretical approach

Separately metal nanoparticles and conducting polymers have applications in fields like adsorption, composite electrode material, dielectrics, photocatalytic, purification, separation, sensing, energy storage, highly conducting materials, etc. But together as a nanocomposite (NCs) very few applications were reported. The silver nanoparticles (NPs) were synthesized by inverse micelle and conducting polymer, polyaniline (PANI) by the low-temperature chemical oxidative method. TEM, photoluminescence, X-ray diffraction, UV–visible, and FTIR techniques were used for the characterization of Ag2O NPs, PANI, and Ag2O@PANI NCs. The computational (DFT) and ab-initio techniques were employed to verify the experimental results. The NCs were tested as an anticorrosive, photocatalytic and antibacterial agent. The maximum corrosion inhibition observed was 90.73% at 1000 ppm of NCs. The photocatalytic property of NCs was investigated against methyl-orange dye in UV light. The NCs degrades 92.53% of organic dye at 100 ppm concentration. The bactericidal activity of Ag2O@PANI NCs was tested against Gram +ve and Gram −ve bacteria and shows 18.2 mm and 20.2 mm zone of inhibition, respectively. The Ag2O@PANI NCs show significant anticorrosive, photocatalytic, and bactericidal properties and hence can be used as a broad-spectrum antibiotic, acid corrosion inhibitor, and for the purification of water by photodegradation of organic pollutants.

Effect of Mn substitution on structural and magnetic properties of cobalt ferrite

Manganese substituted Cobalt Ferrite Co1-xMnxFe2O4() nanoparticles were prepared using low temperature chemical co-precipitation method. All the samples were annealed at 900°C for 3 hours. The crystal lattice symmetry and phase purity were performed by X-ray diffraction (XRD). The varying dopent concentration affects the crystalline size, surface morphology and magnetic properties of the cobalt ferrite. The particle sizes are found to be in the range of 29-37 nm. SEM with EDAX examines the morphological and compositional analysis of the nanoparticles. EDAX confirms the presence of Co, Mn, Fe and O. Fourier transform infrared spectroscopy (FTIR) study confirms the formation of spinel ferrite. The saturation magnetization, magnetic remanence and coercive field of CoMn nanoparticles are obtained at room temperature. Saturation magnetization initially increases and then decreases for higher value of dopent, which shows applicability of these materials for recording media and magnetic data storage. Copyright © 2017 VBRI Press.

Structural and optical characterization of MnFe2O4 nanoparticles

Manganese ferrite nanoparticles with chemical formula MnFe2O4 have been synthesized by low temperature chemical co-precipitation method. The structural and optical properties of the nanoparticles were studied by using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), fourier transform infra-red spectroscopy (FTIR) and UV-visible absorption spectroscopy. XRD confirm pure spinel phase formation of the prepared sample. All the observed peaks correspond to the standard diffraction pattern of manganese ferrite having JCPDS card number 74-2403. From the XRD data, the average crystallite size was calculated and found to be 27.40 nm. The FTIR spectrum shows the characteristic bands of the spinel ferrite. Morphology of the nanoferrites was given by SEM image revealing that the particles are approximately spherical in shape. The elemental composition along with their relative ratios was given by EDAX and was found to be in agreement with their initial calculated values. UV- visible absorption spectrum of the prepared sample shows characteristic absorption in visible range and from the UV-visible absorption data the band gap of the prepared sample was determined. MnFe2O4 nanoparticles were found to possess a narrow band gap of 1.4 eV which may find applications in photocatalytic degradation of pollutants. The simple co-precipitation method proves to be an effective method for synthesis of pure phase manganese ferrite nanoparticles. Copyright © 2017 VBRI Press.

Controlled preparation of Ni(OH)2/NiS nanosheet heterostructure as hybrid supercapacitor electrodes for high electrochemical performance

As a battery-type electrode material, Ni(OH)2 has been widely concerned for its ultra-high theoretical specific capacity, however, its poor conductivity and lack of effective active sites hinder its application. It is a great challenge to develop Ni(OH)2 based supercapacitors. It is critical to improve the electrical conductivity and effective active sites to make full use of the energy storage of Ni(OH)2-based materials. Therefore, Ni(OH)2/NiS composites are designed and prepared by controllable low temperature chemical deposition and ion exchange method. Ni(OH)2 nanosheets with various morphology are controllably prepared by low temperature chemical deposition, and then Ni(OH)2/NiS composites are controllably prepared on Ni(OH)2 substrate by ion exchange. Due to the doping of NiS into Ni(OH)2 nanosheets, the conductive network structure is formed, which makes the composite exhibit excellent electrochemical properties, such as high specific capacity, large specific surface area and good electrical conductivity. The as-fabricated Ni(OH)2/NiS indicates an outstanding specific capacity of 240.5 mAh g−1 at 1 A g−1. This paper detailed studies the practical application of hybrid supercapacitors, which may inspire future researchers to design Ni(OH)2-based materials with desired applications.

Green and sustainable carboxymethyl cellulose-chitosan composite hydrogels: Effect of crosslinker on microstructure

The toxicity level of conventional hydrogels is considerably high for most applications. To date, very few studies on hydrogels synthesized using only safe materials and simple, reproducible processes are available in the literature. Moreover, critical information on hydrogels hydrolytic behavior and stability—important parameters to determine microstructure—is missing. Herein, new composite hydrogel matrices are developed using green, sustainable materials through a simple, reproducible low-temperature chemical method. Natural polymers (carboxymethyl cellulose and chitosan), crosslinkers (fumaric acid, citric acid, tartaric acid and zinc ion), and solvent (water) are used. The hydrogels are characterized for degree of crosslinking and microstructure parameters calculated using Flory Rehner equation. Bonding strength and stability of the microstructure are further assessed. With respect to the hydrolytic properties, it was found that CMC~FU~CSN exhibits well-defined microstructure (155% swelling, 79% water absorbency and 82% gel fraction) superior to the other crosslinked hydrogels and the non-crosslinked composite, CMC~CSN. However, its gel fraction was within the same range as CMC~CSN (332% swelling, 91% water absorbency and 79% gel fraction). Other characterization results confirm that CMC~FU~CSN has the optimum microstructure (3 nm mesh size, 261 g/mol molecular weight between crosslinks and 0.01 μmol/cm3 effective crosslinking density), thermal stability (2% mass loss at 50 °C, 3% at 100 °C against 6% at 50 °C, 8% at 100 °C for CMC~CSN), semi-crystalline structure and chemical properties making it preferred over CMC~CSN as a promising green and sustainable hydrogel matrix.

Synthesis of rare earth metal oxide nanoparticle for simultaneous removal of fluoride and As(III) from aqueous solution

This study aims to investigate the sorption behavior of As(III) in presence of fluoride ion in an aqueous solution. Conventionally the As(III) is removed by converting it to As(V) with certain oxidants followed by sorption or precipitation. Limited information is available for As(III) sorption in presence of fluoride ions. The present study deals with single-step sorption of As(III) in the absence and presence of fluoride ion with rare earth metal oxide as adsorbent. The nanoparticles of CeO2 were synthesized by a low-temperature chemical precipitation method. The CeO2 as adsorbent is tested for sorption of As(III) and fluoride in a single system. The solution pH has a significant role in the sorption of fluoride ion however, negligible effect on As(III) sorption in the pH range of 4–8. The adsorbent showed the significant uptake capacity for arsenic and fluoride even in binary ion systems as 81.9 F mg/g and 3.3 As(III) mg/g respectively. The spent adsorbent is efficiently reused for ion sorption after regeneration and activation.

Tunable design of yolk-shell ZnFe2O4@C composites for enhancing electromagnetic wave absorption

This study shows a simple, layer-by-layer coating process and low-temperature chemical etching method for selective preparation of yolk-shell ZnFe2O4@C composites by using SiO2 as the template. Compared with core-shell ZnFe2O4@SiO2@C, the yolk-shell ZnFe2O4@C microspheres exhibited significantly enhanced electromagnetic wave (EMW) absorption performance in terms of effective bandwidth, coating thickness and minimum reflection loss. The void size can be adjusted just by changing volume of added TEOS, obtaining a series of yolk-shell ZnFe2O4@C composites. It was demonstrated that the Y-2 composite was second to none and its RLmin can drop as low as −37.1 dB at the thickness of 1.4 mm. Besides, its effective bandwidth (RL ≤ −10 dB, 90% absorption) can cover the whole frequency range of 3.8 GHz. Hence, changing void size can reach the best impedance match and tune the EMW absorption performance of samples, which makes yolk-shell ZnFe2O4@C composites be widely used in civil and military fields.

Synthesis and characterization of advanced hybrid titanium compounds/F-MWCNTs nanocomposites and their antibacterial activities

The main objective of this paper is to synthesize advanced hybrid titanium compounds/F-MWCNTs nanocomposites for biomedical applications using a low temperature chemical method followed by an annealing processing. The uniqueness of our approach consists of utilizing the raw materials namely titanium compounds with varying morphological shapes i.e., spherical and nanoflowers nanoparticles for developing advanced nanocomposites A & B having hybrid organic–inorganic titanium compounds namely titanium oxide and sodium titanium oxide, which are conformally impregnated on F-MWCNTs and are useful for biomedical applications. Various techniques such as X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), ThermoGravimetric Analysis (TGA), X-ray Photoelectron Spectroscopy (XPS), Atomic Force Microscopy (AFM), Transmission Scanning Electron Microscopy (TEM), and Energy Dispersive X-ray Analysis (EDX), were performed to study and confirm the structures of the developed advanced hybrid titanium compounds F-MWCNTS nanocomposite. The developed nanocomposite A has shown antibacterial potential against test microbes, gram positive, and gram negative bacteria namely Staphylococcus aureus, Escheria coli, Lactobacillus planetarum, Lactobacillus acidophilus, and Enterococcus faecalis using the disc diffusion method at different concentrations. The developed material is useful for various applications like antibacterial agents, sodium insertion material of sodium ion batteries, shielding radiations like UV, X-rays while performing dental radiographic examinations of the patients.

Understanding the role of uniformly coated carbon overlayers in hematite nanorod photoandes

As one of the most promising photoanode materials, the performance of hematite has been greatly hampered by poor conductivity and severe charge recombination. Here, we report a simple synthesis of N-doped carbon layer coated hematite via low temperature chemical vapor deposition method, where hydroxytyramine hydrochloride (abbreviated as DA) was used as the carbon precursor and hematite thin films as the substrate. The thickness of carbon layers can be adjusted by the amount of DA. The photocurrent densities of the carbon coated hematite nanorods reached up to 1.63 mA cm−2. Based on TEM, XPS, Mott-Schottky and EIS measurement, it was found that the carbon overlayers could simultaneously improve the conductivity in the bulk and passivate the surface state. The correlation between the thickness of carbon layers and the PEC properties were also discussed in detail.