Simple Method for Directly Synthesizing Ag Nanoparticles with Silver Ammonia and Polydopamine in a Microreactor toward the Conversion of 4-NP to 4-AP

Abstract

In this study, a simple method for directly synthesizing Ag nanoparticles on the inner wall of a microreactor was proposed to catalytically convert 4-NP to 4-AP. The proposed method employed silver ammonia as the precursor and polydopamine (PDA) to modify the surface of the microreactor. Because PDA contains numerous reducing agents of phenolic hydroxyl groups, the silver ions can be effectively reduced to Ag nanoparticles. Moreover, due to the zwitterionic nature of PDA, the use of silver ammonia as a precursor, which intrinsically has a high pH value, can allow for more silver ions to be adsorbed on the surface than the conventionally used AgNO 3 as a precursor. Accordingly, the precursor utilization could be greatly improved, leading to the increase of the catalyst loading and thereby boosting the catalytic conversion and durability. It was also found that an increase in the reduction time required for the catalyst preparation could lead to the increase of the catalyst loading and thereby the catalytic performance but a too long reduction time did not continue to make more contribution. Experimental results demonstrate that the microreactor prepared by this simple method is able to exhibit good catalytic activity and durability, providing a new approach for developing high-performance microreactors.

Development and Application of Efficient Ag‐based Hydrogenation Catalysts Prepared from Rice Husk Waste

“…This approach differs significantly form established methods for the reductive generation of AgNPs by adding stoichiometric reductants like NaBH 4 [24] or organoalkoxysilanes, [25] photochemical deposition [26] or the so called auto‐reduction [27] . The carbothermal reduction is made possible by the metal coordination with the donor groups of the plant's biopolymers (Figure 1), an approach which is similar to the fixation of silver ions using dopamine [28] …”

Size-dependent plasmonic activity of AuNPs for the rational design of catalysts for organic reactions

“…With the well-defined methodology in hand, we started our studies with a commonly investigated plasmonic reaction (reduction of NO 2 to a NH 2 group) due to the abundance of this synthetic step in the pharmaceutical industry. 43,44 In contrast with chemical approaches, tuning the parameters of a catalyst (which obviously depends on NP size or illumination mode) allows controlling of the reaction rate for selective reduction in complex molecules/systems containing additional reactive sites. 43,45 In particular, we focused on the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) in the presence of NaBH 4 .…”

Unraveling the Path to Efficient Plasmon Catalysts: Investigating Size Effects of Gold Nanoparticles in Organic Reactions

“…With the well-defined methodology in hands, we have started our studies with the commonly investigated plasmonic reactionreduction of NO2 to NH2 group due to abundance of this synthetic step in the pharmaceutical industry. [49,50] In contrast to chemical approaches, tuning of the catalyst parameters, which are obviously depends on NPs size, or illumination mode allow to control the reaction rate for selective reduction in complex molecules/systems containing additional reactive sites. [49,51] In particular, we focused on the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP)…”