Spectrophotometric analysis of stability of gold nanoparticles during catalytic reduction of 4-nitrophenol

Abstract

Spectrophotometric monitoring of 4-Nitrophenol (4-NP) reduction by Sodium borohydride (NaBH 4) using Gold nanoparticles (GNPs) as a catalyst has been extensively studied, but the stability of GNPs in terms of change in the surface plasmon resonance (SPR) at different temperatures has not been explored. In the present investigation, our aim was to evaluate the SPR stability of GNPs as a catalyst during the reduction of 4-NP at different elevated temperatures i.e., 30-60 °C, and sodium borohydride concentrations. Sensitivity of this degradation process towards concentration of GNPs at a range of temperatures is also evaluated. The spectrophotometric results reveal that up to 45 °C, 12 ± 1.5nm catalyst has a consistent optical density (OD) during whole 4-NP reduction process, which is related to the surface 2 integrity of catalyst atoms. As the temperature approached 50 °C, the OD gradually decreases and shows a blue shift as the reaction proceed which can be related to decrease in particle size or surface dissolution of gold atoms. Present study can find its applications in catalyst designing for the reduction of organic pollutants in industrial waste waters at a range of temperatures.

Enhancing catalytic activity of gold nanoparticles in a standard redox reaction by investigating the impact of AuNPs size, temperature and reductant concentrations

“…Also, the experiments were conducted at lower temperatures i.e., from 5 till 20 °C to see the impact on this range of temperatures. Our previous published reports 5 , 6 on catalysis of nanoparticles for 4-nitrophenol reduction is reported already in which we studied the reaction at higher temperatures i.e., above 20 °C. Current study was dedicated to this lower range of temperatures as catalysis is obviously improved at higher temperatures but our designed catalyst was even useful at lower range of temperatures from 5 till 20 °C.…”

“…Nanotechnology is one of the most versatile technologies because it can be used to create a wide variety of materials, including nanocomposites 1 , 2 , bimetallic nanoparticles 1 – 3 , and quantum dots 4 , all of which have applications as catalysts 5 , 6 . Emerging therapies such as photothermal cancer therapy 7 , electrochemical sensors 8 , medicinal and health care uses treating COVID-19 9 , and antimicrobial nanoparticles 10 , 11 are only a few examples.…”

Antibody-labelled gold nanoparticles synthesized by laser ablation to detect SARS-CoV-2 antigen spike

“…Additionally, according to Saira et al [ 35 ], the stability of AuNPs at different temperatures was examined. AuNPs of a specific size remained stable within a range of temperatures, enduring collisions of reactants and solvent molecules without dissolving their surface atoms.…”

“…This dissolution was attributed to the higher kinetic energy of molecules at elevated temperatures, leading to the surface atoms dissolving into the reaction mixture. This process continued with further temperature increases (50 to 60 °C), but no aggregation was observed [ 35 ].…”

Catalytic Reduction of p-Nitrophenol on MnO2/Zeolite -13X Prepared with Lawsonia inermis Extract as a Stabilizing and Capping Agent

“…Additionally, the reduction of pNP using metal and metal oxide nanoparticle catalysts is very attractive, since it can be achieved in the aqueous solution [ 11 ]. Catalytic reduction of pNP to pAP with the aid of sodium borohydride (NABH 4 ) on a nanoparticles catalyst has been investigated extensively in the literature with different types of nanoparticles or nanocomposite, such as AuCu/Pt nano alloy [ 15 ], silver nanoparticles [ 29 ], Au-ZrO 2 nanocatalyst [ 30 ], Au [ 31 ], Pt, and Pd/SBA-15 [ 3 ], FeNi [ 27 ], Co 9 S 8 [ 26 ], Pd/TiO 2 , [ 23 ], CuO, [ 24 ], magnetic Pt nanocomposites [ 32 ], Au-Pd [ 9 ], Au [ 33 ], SrTiO 3 /Ag [ 34 ], MoS 2 /ZnO [ 35 ], Ag/graphene [ 13 ], Au/TiO 2 [ 25 ], PtPdBi, [ 36 ], Ag/ZnO/AC [ 37 ], Au/AC [ 2 ], Fe/chitosan [ 11 ], and Pd [ 17 ].…”