Ligand Binding to Copper Nanocrystals: Amines and Carboxylic Acids and the Role of Surface Oxides

Oliva-Puigdomènech, Arnau; Roo, Jonathan De; Kuhs, Jakob; Detavernier, Christophe; Martins, José; Hens, Zeger

doi:10.1021/acs.chemmater.8b05107

Cited by 30 publications

(52 citation statements)

References 47 publications

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“…Moreover, OlNH 2 is known to reduce the overall decomposition temperature of the Cu(HCO 2 ) 2 :OlNH 2 complex, originally around 200 • C for pure Cu(HCO 2 ) 2 , to only 120 • C. 43,44 and Cu(I) species along the thermal decomposition route. Such a two step decomposition has indeed been confirmed for the synthesis of Cu NCs from Cu(HCO 2 ) 2 used here, 40 where the reduction from Cu(II) to Cu(I) makes the originally blue reaction mixture turn pale at 120 • C. By furthering increasing the reaction temperature, this step is followed by the subsequent reduction of Cu(I) to Cu(0), which precipitates to form Cu NCs that yield a dark-red/brown reaction mixture. The conversion yield of Cu(HCO 2 ) 2 to metallic Cu was estimated before at ∼ 65%, and the resulting NCs were shown to feature a surface capping of OlNH 2 , which stabilizes the nanocolloid by steric hindrance.…”

Section: Standard Synthesissupporting

confidence: 78%

“…These results confirm the observation made by Dai et al 39 In the case that the OlNH 2 : Cu(HCO 2 ) 2 equivalence is further increased to 8, the particle size is reduced down to 4 nm; a result in line with results we published previously. 40 Hence, we find that in the Cu NC synthesis used here, higher OlNH 2 concentrations induce a more pronounced nucleation event that leads to more, yet smaller NCs at the end of the reaction. Such a trend is different from what is often found in semiconductor NC synthesis, where larger ligand concentrations promote nanocrystal growth, thereby limiting nucleation and resulting in larger NCs.…”

Section: Size-tuning During Cu Nanocrystal Synthesismentioning

confidence: 60%

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Scalable Approaches to Copper Nanocrystal Synthesis under Ambient Conditions for Printed Electronics

Oliva-Puigdomènech

Roo

Avermaet

et al. 2020

ACS Appl. Nano Mater.

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We demonstrate the synthesis of copper nanocolloids by the thermal decomposition of copper formate in oleylamine under ambient conditions. By progressively increasing the loading of copper formate in the reaction mixture and imposing sufficiently high conversion rates, we demonstrate the formation of nanocrystals that are more than 97% pure copper without using an inert atmosphere. We attribute this result to the excess of copper formate relative to initially dissolved oxygen, and to the suppression of oxygen influx in the reactor. By adjusting the precursor and ligand concentrations, we obtain copper nanocrystals with sizes ranging from 10 to 200 nm. In view of applications, we show that the reaction can be upscaled to a 1 L reaction volume to produce over 1 50 grams of copper nanocrystals. Moreover, we formulate a conductive ink based on the copper nanocolloids obtained here with which we printed copper films exhibiting a resistivity of 23 µΩ • cm after thermal sintering under N 2 . We conclude that the approach presented here consititutes a next step towards the cost-effective production of metallic copper nanocrystals for printed electronics.

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Section: Standard Synthesissupporting

confidence: 78%

Section: Size-tuning During Cu Nanocrystal Synthesismentioning

confidence: 60%

Scalable Approaches to Copper Nanocrystal Synthesis under Ambient Conditions for Printed Electronics

Oliva-Puigdomènech

Roo

Avermaet

et al. 2020

ACS Appl. Nano Mater.

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“…The use of oleic acid in the continuous-injection method is necessary for the esterification reaction, but we also believe that amines or thiols could better cap the Cu2O NCs, preventing agglomeration and resulting in smaller particle size. 53,54 We note that a recent report by Kim et al described the effect of nonincorporative cations such as Na + and K + on the synthesis of In2O3 NCs where size and shape were effectively tuned. 11 These results were explained based on the concentration of free and bound oleate ligands, affected by…”

Section: Insights Into Group 13 Catalystsmentioning

confidence: 90%

Group 13 Lewis Acid Catalyzed Synthesis of Cu2O Nanocrystals via Hydroxide Transmetallation

Gibson¹,

Bredar²,

Farnum

2021

Preprint

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The colloidal synthesis of metal oxide nanocrystals (NCs) in oleyl alcohol requires the metal to catalyze an esterification reaction with oleic acid to produce oleyl oleate ester and M-OH monomers, which then condense to form MxOy solids. Here we show that the synthesis of Cu2O NCs by this method is limited by the catalytic ability of copper to drive esterification and thus produce Cu+ -OH monomers. However, inclusion of 1-15 mol% of a group 13 cation (Al3+, Ga3+ , or In3+) results in increased yields for the consumption of copper ions toward Cu2O formation and exhibits size/morphology control based on the nature of M3+ . Using a continuous-injection procedure where the copper precursor (Cu2+ -oleate) and catalyst (M3+ -oleate) are injected into oleyl alcohol at a controlled rate, we are able to monitor the reactivity of the precursor and M3+ catalyst using UV-visible and FTIR absorbance spectroscopies. These time-dependent measurements clearly show that M3+ catalysts drive esterification to produce M3+ -OH species, which then undergo transmetallation of hydroxide ligands to generate Cu+ -OH monomers required for Cu2O condensation. Ga3+ is found to be the “goldilocks” catalyst, producing NCs with the smallest size and a distinct cubic morphology not observed for any other group 13 metal. This is believed to be due to rapid transmetallation kinetics between Ga3+ -OH and Cu + -oleate. These studies introduce a new mechanism for the synthesis of metal oxides where inherent catalysis by the parent metal (i.e. copper) can be circumvented with the use of a secondary catalyst to generate -OH ligands.

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“…Oleylamine (OAM) can be used for synthesizing stable Cu nanoparticles as the protective ligands [ 63 , 64 ]. It tightly binds to the surface of Cu nanoparticles via the Lewis bases of amines to donate its lone pair of electrons.…”

Section: Surface Designs By Surface Protective Layers Against the mentioning

confidence: 99%

Surface and Interface Designs in Copper-Based Conductive Inks for Printed/Flexible Electronics

Tomotoshi

Kawasaki

2020

Nanomaterials

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Silver (Ag), gold (Au), and copper (Cu) have been utilized as metals for fabricating metal-based inks/pastes for printed/flexible electronics. Among them, Cu is the most promising candidate for metal-based inks/pastes. Cu has high intrinsic electrical/thermal conductivity, which is more cost-effective and abundant, as compared to Ag. Moreover, the migration tendency of Cu is less than that of Ag. Thus, recently, Cu-based inks/pastes have gained increasing attention as conductive inks/pastes for printed/flexible electronics. However, the disadvantages of Cu-based inks/pastes are their instability against oxidation under an ambient condition and tendency to form insulating layers of Cu oxide, such as cuprous oxide (Cu2O) and cupric oxide (CuO). The formation of the Cu oxidation causes a low conductivity in sintered Cu films and interferes with the sintering of Cu particles. In this review, we summarize the surface and interface designs for Cu-based conductive inks/pastes, in which the strategies for the oxidation resistance of Cu and low-temperature sintering are applied to produce highly conductive Cu patterns/electrodes on flexible substrates. First, we classify the Cu-based inks/pastes and briefly describe the surface oxidation behaviors of Cu. Next, we describe various surface control approaches for Cu-based inks/pastes to achieve both the oxidation resistance and low-temperature sintering to produce highly conductive Cu patterns/electrodes on flexible substrates. These surface control approaches include surface designs by polymers, small ligands, core-shell structures, and surface activation. Recently developed Cu-based mixed inks/pastes are also described, and the synergy effect in the mixed inks/pastes offers improved performances compared with the single use of each component. Finally, we offer our perspectives on Cu-based inks/pastes for future efforts.

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Ligand Binding to Copper Nanocrystals: Amines and Carboxylic Acids and the Role of Surface Oxides

Cited by 30 publications

References 47 publications

Scalable Approaches to Copper Nanocrystal Synthesis under Ambient Conditions for Printed Electronics

Scalable Approaches to Copper Nanocrystal Synthesis under Ambient Conditions for Printed Electronics

Group 13 Lewis Acid Catalyzed Synthesis of Cu2O Nanocrystals via Hydroxide Transmetallation

Surface and Interface Designs in Copper-Based Conductive Inks for Printed/Flexible Electronics

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