Continuous Synthesis of Reduced Graphene Oxide-Supported Bimetallic NPs in Liquid–Liquid Segmented Flow

Abstract

A segmented flow-based approach was proposed for the deposition of AgPd bimetallic nanoparticles (NPs) on reduced graphene oxide (AgPd/rGO) in continuous mode. AgPd/rGO was synthesized by reducing AgNO 3 and Pd(NO 3 ) 2 simultaneously with NaBH 4 in the presence of graphene oxide (GO) and poly(vinylpyrrolidone) (PVP). The synthesis included two steps, i.e., the formation of AgPd/GO and subsequent reduction of AgPd/GO to AgPd/rGO, which were both confined in dispersed aqueous plugs generated via introducing n-octane. Benefiting from the efficient micromixing in aqueous plugs, the as-prepared AgPd/ rGO exhibited a narrower particle size distribution of AgPd NPs than that synthesized by the batch method. The segmented flowbased method was successfully extended to the preparation of PtPd/rGO and PtCu/rGO composites, demonstrating the versatility of this method. Moreover, the catalytic performance of the resultant AgPd/rGO was better than those of Ag/rGO and Pd/rGO in the catalytic reduction of p-nitrophenol to p-aminophenol because of the synergistic effect between the constituent metals.

CFD Simulation of Internal Flow and Mixing within Droplets in a T-Junction Microchannel

“…Droplet-based microfluidics has been demonstrated to be a potential instrument for the processes such as drug development, chemical engineering, and biotechnology − due to its superior mass transfer performance and mixing efficiency. − These advantages are mainly governed by two elements: interfacial area and internal circulation flow. The internal circulation flow induced by shear stress can intensify chaotic advection to enhance mass transfer and mixing efficiency, , thus playing a significant role in the performance of reactions in droplets.…”

Enhancing Anticorrosion Properties of Micro–Nano Zinc Vanadate from Atomic Modulation Supplemented by Light Modification

“…Polyvinyl pyrrolidone (PVP) was selected as an important surfactant for the synthesis of nanomaterials due to its excellent selective adsorption and easy removability. − The ZVO-1 crystal formed a 3D spherical cluster structure composed of embedded nanowafers (Figure a), which was consistent with the Ostwald ripening process . Time-dependent experiments were performed to reveal the growth process of the ZVO-1 crystal.…”

“…The peaks in 500–1000 cm –1 were all vanadium oxygen vibration peaks, confirming the existence of vanadate. The vibration bands at 500, 588, and 670 cm –1 corresponded to symmetric and asymmetric stretching vibration of V 2 O 7 , − while the strong broad band at 781 cm –1 was attributed to V–O–V tensile vibration . The peaks at 842 cm –1 represented tensile vibration of O–V–O.13 The stretching vibration peak at 912 cm –1 was derived from V–O–Zn.…”

Spontaneous Phase Segregation Enabling Clogging Aversion in Continuous Flow Microfluidic Synthesis of Nanocrystals Supported on Reduced Graphene Oxide

“…Segmented flow microfluidic reactors have been evaluated to prevent clogging by introducing an additional immiscible fluid or an inert gas into the microchannel to split the reaction phase into discrete plugs or droplets [ 14 , 15 ]. Both gas–liquid and liquid–liquid segmented flow systems have been successfully applied to the production of nanoparticles made of varying compositions, including noble metals [ 16 , 17 ], metal oxides [ 18 ], and semiconductors [ 19 ]. Introducing the immiscible liquid or inert gas segments to microfluidic flows requires a very precise design of flow channels and mixers and becomes extremely difficult for thin channels and the high flow rate of reaction fluids.…”