Chemical Synthesis of Metal Nanoparticles Using Amine–Boranes

Abstract

The development of new synthetic strategies to obtain monodisperse metal nanoparticles on large scales is an attractive prospect in the context of sustainability. Recently, amine-boranes, the classical Lewis acid-base adducts, have been employed as reducing agents for the synthesis of metal nanoparticles. They offer several advantages over the traditional reducing agents like the borohydrides; for example, a much better control of the rate of reduction and, hence, the particle size distribution of metal nanoparticles; diversity in their reducing abilities by varying the substituents on the nitrogen atom; and solubility in various protic and aprotic solvents. Amine-boranes have not only been used successfully as reducing agents in solution but also in solventless conditions, in which along with the reduction of the metal precursor, they undergo in situ transformation to afford the stabilizing agent for the generated metal nanoparticles, thereby bringing about atom economy as well. The use of amine boranes for the synthesis of metal nanoparticles has experienced an explosive growth in a very short period of time. In this Minireview, recent progress on the use of amine boranes for the synthesis of metal nanoparticles, with a focus towards the development of pathways for sustainability, is discussed.

Monodisperse nickel nanoparticles in the solvent-free dehydrogenation of dimethylamine borane

“…In this regard, several efficient catalyst systems have been reported involving Ru, Co and Rh NPs [10], Au NPs [11], Cu (airstable), Ag, and Au NPs [4,12] monometallic Au, Ag, Cu, Pd, Ir and bimetallic CuAg and CuAu alloy NPs [13]. Additionally, many transition metal catalysts involving Rh [14e16], Ru [17,18], bimetallic NiPd [19], Ag [20], borane-based catalyst (CoeB, NieB and CueB) [21] have been tested for solutionphase dehydrogenation of amine borane but there is no report concerning the use of dimethylamine-borane by solvent-free approach.…”

Graphene‐Supported Trimetallic Core–Shell Cu@CoNi Nanoparticles for Catalytic Hydrolysis of Amine Borane

“…[16][17][18][19] The hydrolysis of AB [20][21][22][23][24] and thermolysis of AB [25] and its derivative metal amidoboranes (MNH 2 ÀBH 3 ) [26] have been studied widely. [32] AB has been used as the reducing agent to make bimetallic [33,34] and trimetallic [35,36] core-shell NPs, but the reducing ability of MeAB has not been explored widely. [27] The solid-phase thermolysis of MeAB has been studied: [28] Chen showed that by mixing MeAB with poly(methyl acrylate), MeAB could release H 2 at only 90.5 8C (20 8C lower than the temperature required by neat MeAB).…”

“…The reducing strength decreases upon increasing the alkyl substitution on nitrogen: H 3 NÀBH 3 > MeNH 2 ÀBH 3 > Me 2 NHÀBH 3 > Me 3 NÀBH 3 . [32] AB has been used as the reducing agent to make bimetallic [33,34] and trimetallic [35,36] core-shell NPs, but the reducing ability of MeAB has not been explored widely. [30,31,37] Herein, we report a facile in situ method for the preparation of graphene-supported trimetallic core-shell Cu@CoNi NPs through a one-step seeding growth route under ambient conditions, using MeAB as the reducing agent.…”

Synthesis and Mechanism of Formation of Metal Nanosponges and their Catalytic and Hydrogen Sorption Properties

“…Reduction of the metal salt in the absence of capping agent would lead to random 3D architectures . In the past, our group and others established that metal nanoparticles could be obtained via reduction of a metal salt using ammonia borane or substituted amine boranes in both solid and solution states . We attempted to carry out the reduction of metal salts using ammonia borane and substituted amine boranes under different experimental conditions in solution state to investigate the morphological evolution of the resultant material.…”

“…[22] In the past, our group and others established that metal nanoparticles could be obtained via reduction of a metal salt using ammonia borane or substituted amine boranes in both solid and solution states. [27][28][29][30][31][32][33][34] We attempted to carry out the reduction of metal salts using ammonia borane and substituted amine boranes under different experimental conditions in solution state to investigate the morphological evolution of the resultant material. Herein, we studied the effect of: (a) metal salt to ammonia borane ratio (molar and volume to volume), (b) dielectric constant of the solvent in which the reduction was carried out, (c) temperature of the reaction, (d) counter-anion of the metal salt used, and (e) reducing power of various amine boranes.…”