Comparative investigation of zirconium oxide (ZrO2) nano and microstructures for structural, optical and photocatalytic properties

doi:10.1016/j.jcis.2012.09.014

Journal of Colloid and Interface Science

Volume 389, Issue 1, 1 January 2013, Pages 91-98

https://doi.org/10.1016/j.jcis.2012.09.014 Get rights and content

Abstract

ZrO₂ nanocrystals were synthesized by the microwave combustion method (MCM) using urea as the fuel without using any template, catalyst or surfactant. For the purpose of comparison, it was also prepared using the conventional combustion method (CCM). The as-synthesized ZrO₂ was characterized by powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), high resolution scanning electron microscopy (HR-SEM), transmission electron microscopy (TEM), energy dispersive X-ray analysis (EDX), diffuse reflectance spectroscopy (DRS) and photoluminescence (PL) spectroscopy. The results indicated that the ZrO₂ nanocrystals obtained by MCM show high crystallinity and uniform size distribution than the ones prepared by CCM. Hence, the influence of the preparation methods on the structure, morphology and optical activity of ZrO₂ was investigated systematically. Photocatalytic degradation (PCD) of 4-Chlorophenol (4-CP), a potent endocrine disrupting chemical in aqueous medium was investigated by ZrO₂ nanocrystals obtained by MCM. The kinetics of PCD was found to follow pseudo first-order. Having established that ZrO₂ was photo catalytically active, the mixed oxide catalysts of ZrO₂–TiO₂ were also tested for the PCD of 4-CP.

Graphical abstract

Highlights

► Synthesis of ZrO₂ nano and microstructures was achieved by simple combustion method. ► Microwave combustion method was found to be highly facile, efficient and novel. ► The ZrO₂ content has enhanced the photocatalytic activity of TiO_2.

Introduction

Recently, nanomaterials have sparked a worldwide interest due to their unique physical and chemical properties in comparison with those of their bulky counterparts. Nowadays, many techniques, such as co-precipitation, electrodeposition, sol–gel chemistry and solvothermal route, have been developed to synthesize materials in nanoscale, but these strategies are always high-energy consuming and require rather long reaction times. Conventional combustion method (CCM) is self-sustained by its own exothermic reaction, which is an effective method for the mass production of various metal oxides [1], [2], [3], [4]. However, microwave assisted combustion synthesis of materials has recently gained importance over the conventional heating methods, due to the reason that microwaves interact with the reactants at the molecular level, where this electromagnetic energy is transferred and converted to heat by rapid kinetics through the motion of the molecules [5]. This results in the formation of nanoparticles, early phase formation and different morphologies within a few minutes of time [6], [7]. Zirconium oxide, ZrO₂, has been widely investigated due to its potential applications in many fields such as catalysis, restorative dentistry, high temperature ceramics, polymer nanocomposites and sensor, either in pure or its modified state with other metal oxides [8], [9], [10], [11]. It is now well recognized that the mechanical, electrical, chemical, as well as catalytic properties of ZrO₂ can be improved by using nanocrystalline instead of conventional micrometer-sized ZrO₂ due to the unusual surface phenomena at the nanoscale [12], [13], [14]. Nanocrystalline ZrO₂ powders and colloids have been prepared by quite a few methods, including the sol–gel process, combustion, hydrothermal method, microwave irradiation, etc. [15], [16], [17], [18], [19]. However, it is a challenge to find an efficient way to prepare nanocrystalline ZrO₂ with particle size in about several nanometers. Thus, we made an attempt to prepare ZrO₂ by two methods namely, microwave combustion method (MCM), and conventional combustion method (CCM) for comparative investigation of their properties. In combustion experiments, rapid combustion and crystallization using urea as a fuel could generate various structural defects. It is, therefore interesting to examine the defect energy levels and surface states of ZrO₂. Based on the obtained fundamental knowledge, for the first time in the literature, we have prepared ZrO₂ nanostructures with well-crystalline structures and high defect concentration using a MCM approach, while simultaneously avoiding additional calcination procedures. From the results, it is found that MCM is an attractive methodology to control the particle size and properties than CCM. The as-prepared ZrO₂ nanostructures were investigated for optical properties.

Although, TiO₂ is the most widely investigated photo-catalyst, improving its quantum efficiency is still a major challenge. The improvement of photocatalytic activity of TiO₂ can be achieved by doping with metals, the addition of electron donors to the reaction system, and the addition of other semiconductor metal oxides in order to reduce the charge carrier recombination [20]. It has been reported that the addition of ZrO₂ to TiO₂ can increase the surface area and hydroxyl groups in ZrO₂–TiO₂ mixed catalysts which, in turn, improves the quantum efficiency of TiO₂ [21]. Moreover, ZrO₂ and ZrO₂–TiO₂ binary oxide catalysts have been well investigated for their photocatalytic properties [21], [22], [23], [24], [25], [26], [27]. Such advanced ZrO₂–TiO₂ mixed oxides extend their application through the generation of new catalytic sites due to a strong interaction between them. Therefore, it is highly interesting and desirable to study the photocatalytic activity of ZrO₂–TiO₂ mixed oxide.

Section snippets

Preparation of ZrO₂ by simple microwave combustion method (MCM) and conventional combustion method (CCM)

All the reagents used were of analar grade obtained from Merck, India and were used as received without further purification. The combustion method takes advantage of fast and self-sustaining chemical reactions. This method uses the advantage of the propellant chemistry in making the redox mixtures, in which the metal nitrate acts as an oxidizing reactant and fuel as a reducing reactant. Stoichiometric amounts of zirconyl nitrate and urea as fuel are calculated based upon propellant chemistry.

Structural Investigations

ZrO₂ exists mainly in three phases, viz., monoclinic, tetragonal, and cubic. Crystallization of ZrO₂ in a particular phase depends upon the temperature conditions employed during the synthesis and the time of reaction. The XRD patterns were recorded twice on two batches of samples for reproducible results. As shown in Fig. 1a and b, the observed diffraction peaks at 2θ = 30.19°, 35.00°, 50.39°, 58.89°, and 62.85° are associated with [1 1 1], [2 0 0], [2 2 0], [3 1 1], and [2 2 2] plane, respectively. These

Conclusion

ZrO₂ nano-crystals have been successfully synthesized by simple and rapid MCM and ZrO₂ micro-crystals by CCM using urea as the fuel. In comparison with CCM, MCM is not only a quick processes, but also uniformly spreads the heat through the entire bulk of the reaction mixture, which result in the formation of a nanospherical structure with a narrow distribution of particle size. Both MCM and CCM rendered ZrO₂ to crystallize rapidly, assisting in the inclusion of crystal defects. However, MCM

Acknowledgment

The authors duly acknowledge the financial support rendered by the University Grants Commission (UGC) (Ref. F. No. 38-118/2009 (SR)), New Delhi.

References (46)

R.V. Mangalaraja et al.
Powder Technol.
(2009)
H. Mohebbi et al.
Powder Technol.
(2009)
J. Xi et al.
Chem. Phys. Lett.
(2004)
C. Santos et al.
J. Mater. Process. Technol.
(2008)
Y. Wu et al.
Mater. Sci. Eng. A
(2004)
N.T. Kalyana Sundaram et al.
J. Phys. Chem. Solids
(2007)
H. Yang et al.
J. Power Sources
(2006)
J.A. Navio et al.
J. Photochem. Photobiol. A
(1997)
B. Neppolian et al.
Appl. Catal. A
(2007)
S. Onsuratoom et al.
Int. J. Hydrogen Energy
(2011)

L.Y. Zhu et al.

Appl. Catal. B

(2011)

M. Hirano et al.

J. Solid State Chem.

(2003)

C. Shao et al.

J. Cryst. Growth

(2004)

E. Esmaeili et al.

J. Eur. Ceram. Soc.

(2009)

L. Gao et al.

Mater. Chem. Phys.

(2008)

Y. Cong et al.

J. Lumin.

(2007)

K. Smits et al.

J. Lumin.

(2011)

Y. Bessekhouad et al.

J. Photochem. Photobiol., A

(2004)

S.K. Pardeshi et al.

J. Mol. Catal. A

(2009)

N.C.S. Selvam et al.

Powder Technol.

(2011)

H. Chun et al.

Appl. Catal. B

(2001)

C. Xie et al.

Mater. Sci. Eng., B

(2004)

K. Deshpande et al.

Chem. Mater.

(2004)

Cited by (125)

CO<inf>2</inf> hydrogenation to methanol over Zr- and Ce-doped indium oxide
2023, Catalysis Today
In recent decades, climate change has become a major issue that needs to be addressed. Many efforts have been made on the reduction of CO₂ emissions and its conversion in energy carriers and high value-added products such as methane, methanol, dimethyl-ether, and hydrocarbons. The present study focuses on the development of catalysts for hydrogenating CO₂ to methanol, which is a useful chemical and an alternative liquid fuel. According to the literature, In₂O₃-based catalysts are particularly selective in the hydrogenation of CO₂ to methanol, reducing the production of CO even at high space velocities compared to the more common ternary catalysts such as Cu/ZnO/Al₂O₃ or Cu/ZnO/ZrO₂. Therefore, the effects of CeO₂ and ZrO₂ on In₂O₃-based catalysts were investigated in the present study. The In_xCe_100−x and the In_xZr_100−x mixed oxides catalysts were synthesized via gel-oxalate coprecipitation by varying the atomic ratios between the elements. Subsequently, they were analysed with several characterisation techniques to rationalise the catalytic performances that were obtained by testing the samples in a fixed bed reactor under different reaction conditions. The addition of different amounts Ce or Zr modified the structure and morphology of the samples and promoted the adsorption of CO₂ from 1.8 mmol_CO2⋅g_cat⁻¹ up to 10.6 mmol_CO2⋅g_cat⁻¹. ZrO₂ stabilises the structure and the results suggests that the greater specific activity (168 mg_CH3OH⋅g_In2O3⁻¹⋅h⁻¹ at 300 °C and 2.5 MPa of In₄₀Zr₆₀) could be ascribed to the electronic promotion of Zr. On the contrary, the addition of CeO₂ did not reveal a beneficial effect on the activity. Concerning the stability, In₂O₃-ZrO₂ binary oxides seemed to be affected mainly by sintering; whereas In₂O₃-CeO₂ were affected by at least three deactivating phenomena: sintering, reduction of In₂O₃ to metallic indium and coking. Consequently, the deactivation rate of these binary oxides increased from 1.04 ⋅ 10⁻² h⁻¹ of the In₁₀₀ to 4.13 ⋅ 10⁻² h⁻¹ of the In₄₀Ce₆₀.
Enhancement of antibacterial and anticancer properties lanthanum insight into zinc oxide nanoparticles prepared via coprecipitation process
2023, Inorganic Chemistry Communications
The development of La-doped ZnO NPs exhibits potential to improve the biocidal properties of nanomaterials for medical applications to treat MDR bacteria and breast cancer activity. A co-precipitation process was used to make zinc oxide (ZnO) nanoparticles (NPs) and lanthanum dopedZnO (ZnLaO) NPs. XRD patterns revealed the hexagonal wurtzite structure of the ZnO and ZnLaO NPs. Zn-O stretching frequencies, ZnO, and ZnLaO were found in the FTIR spectra at 486 and 556 cm-1, respectively. SEM and EDAX spectra validated the shape and chemical composition of ZnO and ZnLaO NPs. Based on UV–Vis spectroscopic measurements, the excitonic peaks for the two samples were found to be about 367 nm and 364 nm, respectively. The PL experiments were conducted at room temperature, and green emission peaks were observed in the visible range for ZnO and ZnLaO NPs at 522 and 525 nm, respectively. ZnO and ZnLaO NPs were examined for antibacterial activity against gram-positive bacteria (S. aureus and B. subtilis) and gram-negative bacteria (E. coli and K. pneumonia) bacterial strains. The ZnLaO NPs potential antibacterial activity was higher than that of ZnO NPs alone, and increasing the concentration of ZnLaO NPs also increased the antibacterial activity. Furthermore, the ZnO and ZnLaO NPs were treated with human breast cancer (MCF-7) cell lines. The ZnLaO NPs exhibit more anticancer activity at a minimum concentration. As a result of these investigations, theZnLaO NPs can make antibacterial and anticancer agents and those employed in biomedical applications.
Effect of ZnO on sintering and microwave dielectric properties of 0.5CaTiO<inf>3</inf>-0.5 (Li<inf>0.5</inf>La<inf>0.5</inf>) TiO<inf>3</inf> ceramics
2023, Journal of the Indian Chemical Society
The novel calcium titanate-lithium lanthanum titanate doped with zinc oxide (0.10, 0.30, and 0.50 mol. %) ceramic samples were prepared by solid-state reaction route. The phase formation, microstructure, densification, and microwave dielectric properties were investigated. It was found that the doping with zinc oxide led to a decrease in sintering temperature by 25 ^oC as compared with pure calcium titanate lithium lanthanum titanate due to the liquid phase effect. Also, the calcium titanate lithium lanthanum titanate (10ZCTLLT&30ZCTLLT)) doped with lower zinc oxide (0.10 and 0.30 mol. %) led to higher densification parameter. This was followed by increasing the zinc oxide doping up to (0.50 mol. %) which resulted in a decrease in densification and microwave dielectric properties which may be attributed to increase in porosity and grain growth upon the evaporation of zinc and oxygen vacancy. This led to the increase in dielectric loss (≈10 × 10⁻⁴) value with 50ZCTLLT. Hence, the best result of microwave dielectric characteristics was obtained for 0.5CaTiO₃–0.5(Li_0.5La_0.5)TiO₃ with (0.10 and 0.30 mol. % ZnO) 10ZCTLLT and 30ZCTLLT ceramic samples sintered at 1175 ^oC/2h, with low dielectric constant (ε_r) = 4.4–10.5, very low dielectric loss = 1.07-2.23 × 10⁻⁴ and high quality factor (Q x ƒ) ≈59-55 × 10⁴ at 8 GHz. Consequently, they can be used not only in wireless satellite communications technology but also can be used in the fifth-generation telecommunication 5G technology construction.
Li<inf>2</inf>MnO<inf>3</inf>@ZrO<inf>2</inf> heterojunctions for highly efficient catalytic photodegradation of Atrazine herbicide
2022, Ceramics International
Atrazine is a herbicide broadly utilized in various agricultural and food-processing applications. For the first time, novel Li₂MnO₃@ZrO₂ (LMO@ZrO₂) heterostructures were synthesized by a self-assembly route in the presence of nonionic triblock copolymer with incorporating small doses (0.5–2.0 wt%) of LMO. The synthesized samples were characterized by different instruments, which confirmed the formation of nanostructured monoclinic LMO@ZrO₂ with average crystallite sizes of 25–36 nm and high specific areas of 171–235 m²/g without affecting the basic structural or surface features. The synthesized photocatalysts were evaluated for mineralization and removal of Atrazine in aqueous media under visible illumination. Light absorption, photogenerated mobility, and separation were enhanced upon appropriate doping trace amounts of LMO, which lowered the bandgap to 2.16 eV and hence making them promising candidates for herbicide removal. Composite with only 1.5 wt % LMO content exhibited a full Atrazine photoelimination compared to pristine ZrO₂ (66%) after 1 h of visible light illumination. The kinetic rate constant is greatly improved over LMO@ZrO₂ heterostructures, the 1.5% LMO@ZrO₂ composite yielding a high kinetic rate constant of 0.0434 min⁻¹, which was increased by 2.25-fold over pristine ZrO₂ (0.0193 min⁻¹). Furthermore, the LMO@ZrO₂ heterojunctions also demonstrated stellar recyclability regarding the photodegradation of Atrazine. A probable mechanism for carrier charges separation through mesoporous LMO@ZrO₂ heterostructures was suggested. This study supports the application of nanoheterojunction oxides for green herbicide treatments.
Hollow structured Cu@ZrO<inf>2</inf> derived from Zr-MOF for selective hydrogenation of CO<inf>2</inf> to methanol
2022, Journal of Energy Chemistry
The development of a highly efficient catalyst for CO₂ activation and selective conversion to methanol is critical to address the issues associated with the high thermal stability of CO₂ and controllable synthesis of methanol. Cu-based catalysts have been widely studied because of the low cost and excellent performance in mild conditions. However, the improvement of catalytic activity and selectivity remains challenging. Herein, we prepared hollow Cu@ZrO₂ catalysts through pyrolysis of Cu-loaded Zr-MOF for CO₂ hydrogenation to methanol. Low-temperature pyrolysis generated highly dispersed Cu nanoparticles with balanced Cu⁰/Cu⁺ sites, larger amounts of surface basic sites and abundant Cu-ZrO₂ interface in the hollow structure, contributing to enhanced catalytic capacity for adsorption/activation of CO₂ and selective hydrogenation to methanol. In situ Fourier Transform Infrared Spectroscopy revealed the methanol formation followed the formate-intermediated pathway. This work would provide a guideline for the design of high-performance catalysts and the understanding of the mechanism and active sites for CO₂ hydrogenation to methanol.
Horizontally aligned BN nanosheet array for nanometer-thick ZrO<inf>2</inf> coating with greatly enhanced anticorrosion and hydrogen isotope resistance property
2022, Chemical Engineering Journal
Monolayer graphene and hexagonal boron nitride (h-BN), as representative of two-dimensional crystals, are surprisingly impenetrable to all gases and small ions. This essential characteristic boosts them as superior materials for developing novel separation and coating technologies. However, whether graphene is an effective filler in anti-corrosion coatings is controversial for its high electrical conductivity. Compared with graphene, h-BN nanosheet is almost insulative, but bad dispersibility of BN nanosheet seriously hinders its application as coating fillers. Herein we show that few-layer h-BN nanosheets fabricated by one-step mechano-chemical process are highly water-dispersible, thanks to the hydroxyl groups contained in h-BN. These water-dispersible h-BN nanosheets were horizontally aligned in nanometer-thick ZrO₂ coating by a simple sol–gel method, serving as ideal blocks for hindering ions and hydrogen isotope from transfer across the coating. With h-BN nanosheets incorporated, the 50 nm thick hybrid BN/ZrO₂ coating displays an outstanding anticorrosion ability. An ultra low corrosion current density of 1.59 × 10^-9A/cm² was achieved at 0.8 mg/ml BN/ZrO₂, which is 2767 times lower than 316L steel substrate and 102 times lower than pure ZrO₂ coating. For the first time, hydrogen isotope resistance property was tested for nanosheet-inserted hybrid coatings to evaluate the effect of nanosheets on blocking hydrogen isotopes. The deuterium permeability is 1.97 × 10^-15 mol m⁻¹ s⁻¹ Pa^−0.5 at 400 °C for 0.8 mg/ml BN/ZrO₂. The hydrogen isotope resistance of the hybrid coating is 140 times that of 316L, increasing by more than 25% when compared to pure ZrO₂. The results demonstrate that h-BN nanosheets are highly effective in reducing ions and gases permeation. These advantages endow nanosheet-hybrid-coating a great potential as barrier material for various applications including anticorrosion and anti-hydrogen embrittlement for structural materials.

View all citing articles on Scopus

View full text

Comparative investigation of zirconium oxide (ZrO2) nano and microstructures for structural, optical and photocatalytic properties

Abstract

Graphical abstract

Highlights

Introduction

Section snippets

Preparation of ZrO2 by simple microwave combustion method (MCM) and conventional combustion method (CCM)

Structural Investigations

Conclusion

Acknowledgment

Powder Technol.

Powder Technol.

Chem. Phys. Lett.

J. Mater. Process. Technol.

Mater. Sci. Eng. A

J. Phys. Chem. Solids

J. Power Sources

J. Photochem. Photobiol. A

Appl. Catal. A

Int. J. Hydrogen Energy

Appl. Catal. B

J. Solid State Chem.

J. Cryst. Growth

J. Eur. Ceram. Soc.

Mater. Chem. Phys.

J. Lumin.

J. Lumin.

J. Photochem. Photobiol., A

J. Mol. Catal. A

Powder Technol.

Appl. Catal. B

Mater. Sci. Eng., B

Chem. Mater.

Comparative investigation of zirconium oxide (ZrO₂) nano and microstructures for structural, optical and photocatalytic properties

Preparation of ZrO₂ by simple microwave combustion method (MCM) and conventional combustion method (CCM)