Thermal decomposition synthesis of Al-doped ZnO nanoparticles: an in-depth study

Damm, Hanne; Kelchtermans, Anke; Bertha, A.; Broeck, Freya Van den; Elen, Ken; Martins, José; Carleer, Robert; D’Haen, Jan; Dobbelaere, Christopher De; Hadermann, Joke; Hardy, An; Bael, Marlies K. Van

doi:10.1039/c3ra43328e

Cited by 13 publications

(5 citation statements)

References 49 publications

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“…In line with previous studies on CdSe, 28,40 PbS, 41,42 and InP 43 NCs, we have demonstrated that carboxylic acids bind as carboxylates to HfO 2 and ZrO 2 NCs. Using IR spectroscopy, similar conclusions were arrived at for Fe 2 O 3 , 17 MFe 2 O 4 (M = Fe, Mn, and Co), 44 ZnO, 45 and ZrO 2 46 NCs, yet the combination with NMR spectroscopy enables us to complement this finding with the observation that, in the case of HfO 2 and ZrO 2 , the negative charge on the carboxylate moieties is balanced by surface adsorption of protons rather than by excess metal cations. Moreover, carboxylic acids will only bind as carboxylates on the as-synthesized NCs provided that a sufficient amount of oleylamine is supplied, which removes hydrogen chloride initially present at the surface.…”

Section: ■ Discussionsupporting

confidence: 64%

Unravelling the Surface Chemistry of Metal Oxide Nanocrystals, the Role of Acids and Bases

et al. 2014

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We synthesized HfO2 nanocrystals from HfCl4 using a surfactant-free solvothermal process in benzyl alcohol and found that the resulting nanocrystals could be transferred to nonpolar media using a mixture of carboxylic acids and amines. Using solution (1)H NMR, FTIR, and elemental analysis, we studied the details of the transfer reaction and the surface chemistry of the resulting sterically stabilized nanocrystals. As-synthesized nanocrystals are charge-stabilized by protons, with chloride acting as the counterion. Treatment with only carboxylic acids does not lead to any binding of ligands to the HfO2 surface. On the other hand, we find that the addition of amines provides the basic environment in which carboxylic acids can dissociate and replace chloride. This results in stable, aggregate-free dispersions of HfO2 nanocrystals, sterically stabilized by carboxylate ligands. Moreover, titrations with deuterated carboxylic acid show that the charge on the carboxylate ligands is balanced by coadsorbed protons. Hence, opposite from the X-type/nonstoichiometric nanocrystals picture prevailing in literature, one should look at HfO2/carboxylate nanocrystals as systems where carboxylic acids are dissociatively adsorbed to bind to the nanocrystals. Similar results were obtained with ZrO2 NCs. Since proton accommodation on the surface is most likely due to the high Brønsted basicity of oxygen, our model could be a more general picture for the surface chemistry of metal oxide nanocrystals with important consequences on the chemistry of ligand exchange reactions.

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Section: ■ Discussionsupporting

confidence: 64%

Unravelling the Surface Chemistry of Metal Oxide Nanocrystals, the Role of Acids and Bases

et al. 2014

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“…proposed an analogues C−C cleavage mechanism with the elimination of acetone and ester for the formation of Al‐doped ZnO nanoparticles by the thermal decomposition of the metal acetylacetonates with 1,2‐hexadecanediol. In addition to acetone, thermal decomposition products of ester such as acetic acid, a mixture of alkanes and alkenes, carbon dioxide and water were detected using headspace GC analysis during the synthesis of ZnO:Al nanoparticles …”

Section: Chemical Formation Mechanismsmentioning

confidence: 99%

“…In addition to acetone, thermal decomposition products of ester such as acetic acid, am ixture of alkanes and alkenes, carbon dioxide and water were detected using headspace GC analysis duringt he synthesis of ZnO:Al nanoparticles. [174] Zhang et al developed anonaqueousroute for the synthesis of phase-pure transition metal niobates (InNbO 4 ,M nNb 2 O 6 , and YNbO 4 )b ased on the solvothermalr eactiono fn iobium chloridea nd the corresponding transition metal acetylacetonates in benzyl alcohol. [175] The chemical mechanismsr esponsible for the oxygen supply were based on three almosts imultaneously occurring processes as shown in Scheme 9: a) Am etal promoted alcoholysis of the acetylacetonate ligand leading to the formation of an enolate and benzyl acetate, b) release of acetonet hrough the coordination of benzyla lcohol to the metal center,a nd c) benzyl ether elimination catalyzedb yt he niobium center.…”

Section: Reaction Between Metal Acetylacetonates and Alcoholsmentioning

confidence: 99%

Mechanistic Aspects in the Formation, Growth and Surface Functionalization of Metal Oxide Nanoparticles in Organic Solvents

Deshmukh

Niederberger

2017

Chemistry A European J

106

112

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The synthesis of metal oxide nanoparticles in organic solvents, so-called nonaqueous (or nonhydrolytic) processes represent powerful alternatives to aqueous approaches and have become an independent research field. 10 Years ago, when we published our first review on organic reaction pathways in nonaqueous sol-gel approaches, the number of examples was relatively limited. Nowadays, it is almost impossible to provide an exhaustive overview. Here we review the development of the last few years, without neglecting pioneering examples, which help to follow the historical development. The importance of a profound understanding of mechanistic aspects of nanoparticle crystallization and formation mechanisms can't be overestimated, when it comes to the design of rational synthesis concepts under minimization of trial-and-error experiments. The main reason for the progress in mechanistic understanding lies in the availability of characterization tools that make it possible to monitor chemical reactions from the dissolution of the precursor to the nucleation and growth of the nanoparticles, by ex situ methods involving sampling after different reaction times, but more and more also by in situ studies. After a short introduction to experimental aspects of nonaqueous sol-gel routes to metal oxide nanoparticles, we provide an overview of the main and basic organic reaction pathways in these approaches. Afterwards, we summarize the main characterization methods to study formation mechanisms, and then we discuss in great depth the chemical formation mechanisms of many different types of metal oxide nanoparticles. The review concludes with a paragraph on selected crystallization mechanisms reported for nonaqueous systems and a few illustrative examples of nonaqueous sol-gel concepts applied to surface chemistry.

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“…Deposition of colloidal TCO NCs as a nanoink is highly appealing for integration into emerging flexible electronics, such as displays, electronic paper, or solar cells [6,7]. While the synthesis of ZnO:Al nanocrystals and films has recently advanced markedly, it still remains a challenge to control dopant incorporation in zinc oxide based TCO NCs [8][9][10][11][12][13][14][15][16]. Even more, probing doping efficiency and understanding whether or not dopants have substituted the desired host atoms are not trivial.…”

Section: Introductionmentioning

confidence: 99%

Increasing the Solubility Limit for Tetrahedral Aluminium in ZnO:Al Nanorods by Variation in Synthesis Parameters

Kelchtermans

Adriaensens

Slocombe

et al. 2015

Journal of Nanomaterials

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Nanocrystalline ZnO:Al nanoparticles are suitable building blocks for transparent conductive layers. As the concentration of substitutional tetrahedral Al is an important factor for improving conductivity, here we aim to increase the fraction of substitutional Al. To this end, synthesis parameters of a solvothermal reaction yielding ZnO:Al nanorods were varied. A unique set of complementary techniques was combined to reveal the exact position of the aluminium ions in the ZnO lattice and demonstrated its importance in order to evaluate the potential of ZnO:Al nanocrystals as optimal building blocks for solution deposited transparent conductive oxide layers. Both an extension of the solvothermal reaction time and stirring during solvothermal treatment result in a higher total tetrahedral aluminium content in the ZnO lattice. However, only the longer solvothermal treatment effectively results in an increase of the substitutional positions aimed for.

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Thermal decomposition synthesis of Al-doped ZnO nanoparticles: an in-depth study

Cited by 13 publications

References 49 publications

Unravelling the Surface Chemistry of Metal Oxide Nanocrystals, the Role of Acids and Bases

Unravelling the Surface Chemistry of Metal Oxide Nanocrystals, the Role of Acids and Bases

Mechanistic Aspects in the Formation, Growth and Surface Functionalization of Metal Oxide Nanoparticles in Organic Solvents

Increasing the Solubility Limit for Tetrahedral Aluminium in ZnO:Al Nanorods by Variation in Synthesis Parameters

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