Conversion Mechanism of Soluble Alkylamide Precursors for the Synthesis of Colloidal Nitride Nanomaterials

Abstract

There are few molecular precursors that chemically convert to nitride nanomaterials, which severely limits the development of this important class of materials. Alkylamides are soluble and stable nitride precursors that can be based on the same primary amines that are often used in colloidal nanomaterial synthesis, but their conversion involves the breaking of stable C-N bonds through a mechanism that remained unknown up to now. A critical aspect of this conversion mechanism is uncovered here, involving a prelimary step whereby alkylamides are oxidized to N-alkylimines to yield NH amide species that are postulated to be the actual reactive precursors in the formation of indium nitride nanomaterials. Interestingly, this step also involves the concomitant reduction of indium(III) to In(0) nanodroplets, which consequently catalyze the growth of InN nanomaterials. The elucidation of the origin of the surprising reactivity of otherwise stable molecular precursors opens the door to the development of new solution-phase approaches for the synthesis of nitride materials.

Photodoping of metal oxide nanocrystals for multi-charge accumulation and light-driven energy storage

“…Recent works described the capacitive properties of InN NCs. 86,87 These have a significantly lower bandgap in the visible/near-infrared regimes. Photodoping of such NCs would represent an important step towards storing a larger potential of solar energy.…”

Ligand Conversion in Nanocrystal Synthesis: The Oxidation of Alkylamines to Fatty Acids by Nitrate

“…48,49 Aldimine 6 is observed in the reaction mixture and is also a common byproduct of the synthesis of nitrides. 50 The formation of 6 entails the evolution of ammonia, which we detected in the gas phase (see SI p. S16). The intermediate 4 can not detected in the reaction mixture (Figure 2), which we attribute to the low stability of primary aldimines.…”

“…Alkylamines have been used as reducing agents, 54,55 or as a source of ammonia. 50 Certain side reactions were reported, such as the oxidation to nitriles, 47,56,57 or the condensation with carboxylic acids. 53 However, none of these previously reported transformations yielded byproducts with high binding affinity for the NC surface.…”

Rapid, facile synthesis of InSb twinning superlattice nanowires with a high-frequency photoconductivity response

“…44 In striking comparison to the energy-intensive and time-consuming vapor-phase growth approaches, solution-based route via solution-liquid-solid (SLS) mechanism can proceed at relatively low temperatures (<300 C) and provide semiconductor nanowires with easy growth processes and adaptability for large-scale fabrication of nanowire-based devices. [45][46][47] Therefore, extensive efforts have been mostly focused on growing InSb twinning superlattice nanowires via solution-phase growth approaches. Luckily, recent progress indicates that InSb nanostructures such as quantum dots and nanorods can be successfully prepared by solution-phase techniques.…”

“…On the basis of previous works on fabricating InSb nanostructures in solution, 40,47,49,50 we present a facile, one-pot, selfcatalyzed synthetic strategy by the well-established SLS mechanism 45,46,52,53 to grow InSb twinning superlattice NWs featuring fastest growth time (1 min) and lowest synthesis temperature (175 C), which even compared to other binary or pseudobinary III-V semiconductor nanowires with twinning superlattice structures formed via SLS as well as VLS growth mechanism. 16,19,20,[23][24][25]50,54 Furthermore, by means of the noncontact technique-optical pump-terahertz probe (OPTP) spectroscopy, we extract the ultrashort relaxation and recombination dynamics of photoconductivity lifetime in as-prepared InSb twinning superlattice NWs of just 9.1 ps at room temperature, indicating their great potential for high-speed photodetectors, transistors, and emitters.…”