In this paper, Fe 3 O 4 /Ag/RGO reusable ternary nanocomposites are explored via a facile one-pot solvothermal strategies, and the catalytic performance and antibacterial activity are investigated in detail. The catalytic performance of Fe 3 O 4 /Ag/RGO towards the reduction of 4-NP into 4-AP is evaluated, and the reaction rate constant ( k ) for Fe 3 O 4 /Ag/RGO is calculated to be 0.03086 s −1 , which is higher than that of Fe 3 O 4 /Ag (0.01756 s −1 ), indicating the catalytic activity is improved after decorating Fe 3 O 4 /Ag onto the graphene sheet. The antibacterial experiment shows Fe 3 O 4 /Ag/RGO ternary nanocomposites present a wide range of antibacterial activities against Gram-positive bacteria ( S. aureus and B. cereus ) and Gram-negative bacteria ( E. coli and P. aeruginosa ). The minimal inhibitory concentrations (MIC) for Fe 3 O 4 /Ag/RGO nanocomposites against four bacterial species are determined. Additionally, Fe 3 O 4 /Ag/RGO nanocomposites also present high reusability as catalyst and antibacterial agent. The results illustrated in this paper imply that the multifunctional performances such as efficient reduction of 4-NP followed by superior anti-reproduction of pathogenic bacteria make the Fe 3 O 4 /Ag/RGO ternary nanocomposites a promising catalyst for dye-polluted water and disinfectant agent for wastewater treatment and purification.
Yuxiao Yang,Min Jiang,Kaihang Cao,Mei Wu,Chulei Zhao,Hongling Li,Chenglin Hong
An electrochemical immunosensor for quantitation of carcinoembryonic antigen (CEA) based on Au-Ag/ [email protected] nanocomposites for dual signal amplification strategy was designed. Polydopamine-coated Ag/graphene hybrids were synthesized by one-step reduction and functionalization, and the dopamine was introduced to replace some reducing agents that are harmful to organisms. Silver nanoparticles modified on the electrodes produced sensitive electrochemical redox peaks. When different amounts of protein (antigen, antibody, bovine serum protein, etc.) were adsorbed on the surface of nano-silver, the surface of nano-silver was covered. The electrochemical redox peak of silver particles decreased due to the change of the effective area of bare silver particles which could react with electrodes. In addition, CEA-antibody (anti-CEA) was immobilized into a biocompatible nanocomposite of Au nanoparticles as a conductive matrix, and CEA-antibody (anti-CEA) was combined with Ag/ [email protected] to form a dual signal amplifying element. Under optimal condition, the linear relationship was obtained from 0.001 ng mL −1 to 80 ng mL −1 between current signal and CEA concentration with a detection limit of 0.286 pg mL −1 (signal-to-noise ratio is 3). The label-free electrochemical immunosensor has been successfully applied to human serum detection due to good selectivity , stability and reproducibility.
Phase change material (PCM) is a promising energy material for applications, but their inherent drawbacks, such as poor thermal conductivity and vulnerability to leakage, strongly limit their use in efficient energy storage and thermal management. To overcome these drawbacks, this paper innovatively uses a high-temperature one-step reduction method to simultaneously prepare Ag particles and reduced graphene oxide (rGO) and carbonize melamine foam (CMF) to improve thermal conductivity as well as photo-thermal conversion, and ultimately a series of shape-stable thermally conductive reinforced composite phase change material (CPCM) are prepared using vacuum impregnation. The high-density three-dimensional thermal conductivity network of Ag@rGO-CMF was able to significantly increase the thermal conductivity of CPCM (up to 104.2 % enhancement). The prepared CPCM have high loading ratios (96.9 % ~ 97.8 %), high enthalpies (154–157.7 J/g), high photo-thermal conversion efficiencies (81.3 % ~ 90.5 %), and excellent thermal management capabilities of electronic devices. This study provides a simple and feasible method for the preparation for high performance CPCM.
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