Decoration Of Au Nanoparticles Research Articles

Bifunctional Electrocatalyst Enhanced Synergistically by MoS2/Ni3S2 Heterojunctions and Au Nanoparticles for Large‐Current‐Density Overall Water Splitting

AbstractDeveloping transition metal based overall water splitting (OWS) electrocatalysts with high efficiency, low‐cost, large current density, and long‐term stability is crucial for industrial electrolysis of water, but remains a major challenge. In this study, a hierarchical electrocatalyst with MoS2/Ni3S2 heterojunctions and a tiny amount of Au nanoparticles grown on nickel foam (MoS2/Ni3S2‐Au@NF) has been developed by a one‐step hydrothermal method. The heterojunctions and Au nanoparticle decoration induce the electron‐rich interfaces in the catalyst, which facilitate the synergistic adsorption of both OER and HER intermediates. As a result, MoS2/Ni3S2‐Au@NF possesses an excellent bifunctional electrocatalytic performance in 1 M KOH with low HER overpotential (78 mV@10 mA cm−2, 253 mV@500 mA cm−2), low OER overpotential (261 mV@50 mA cm−2, 435 mV@500 mA cm−2), and outstanding cyclical stability and continuous stability, which are superior than typical benchmarks of Pt/C and RuO2. An electrolyzer assembled with the self‐supported MoS2/Ni3S2‐Au@NF electrode also displays excellent OWS activity and stability with a current density beyond 100 mA cm−2. This experiment is responding a potential alternative non‐precious metal electrocatalyst for OWS at industrial settings, and thus promotes the real‐world application of hydrogen energy conversions.

Ratiometric electrochemical and impedimetric dual-mode aptasensor based on thionine-functionalized Ti3C2Tx MXene/Pt and Au nanoparticle composites for reliable detection of aflatoxin B1

Rapid and reliable detection of aflatoxin B1 (AFB1) is critical in public health, food safety and environmental control. Herein, a ratiometric electrochemical (EC) and electrochemical impedance spectroscopy (EIS) dual-mode aptasensing platform based on thionine-functionalized Ti3C2Tx MXene/Pt and Au nanoparticle composites (MXene@Thi/PtAuNPs) was constructed for accurate and reliable detection of AFB1. The MXene@Thi/PtAuNPs composites were prepared by a facile and mild approach. The electroactive molecule Thi embedded in MXene could not only inhibit the aggregation of MXene nanosheets, but also act as an internal reference probe to form a ratiometric sensing strategy. The decoration of Pt and Au nanoparticles can further effectively enhance the conductivity and catalytic activity of the composites. The MXene@Thi/PtAuNPs composites were then served as a support to sequentially assemble hairpin DNA (hDNA) and ferrocene-labelled AFB1 aptamer (Fc-Apt) to construct the dual-mode sensor. The developed dual-mode sensor with both ratiometric EC detection (based on IThi/IFc) and EIS detection (based on Ret) can mutually verify the detection results obtained by two modes, offering more accurate and reliable results, which enabled sensitive and reliable AFB1 detection in the concentration range of 10.0 pg mL−1-30.0 ng mL−1 (ratiometric EC mode) and 3.0 pg mL−1-30.0 ng mL−1 (EIS mode), respectively. The sensing platform also demonstrated favorable selectivity, reproducibility and stability, and satisfactory applicability in corn sample, showing great potential in the sensing of mycotoxins in agricultural products.

The cooperative p-n heterojunction and Schottky junction in Au-decorated hierarchical CuS@SnS2 hollow cubes for boosted charge transport and CO2 photoreduction

During the photocatalytic CO2 reduction process, fast charge transport, abundant active sites, and high visible light utilization in photocatalysts are key to achieving excellent CO2 conversion efficiency. In this work, we have designed and prepared hierarchical CuS@SnS2p-n heterostructure hollow cubes for photocatalytic CO2 reduction. First, a monolayer of CuS was in situ generated on the pre-prepared Cu2O cubes to construct core–shell Cu2O@CuS cubes by sulfidation of Cu2O cubes. The following etching process led to the formation of CuS hollow cubes. Finally, the hierarchical CuS@SnS2p-n heterostructure hollow cubes were obtained by growing SnS2 nanosheets on the CuS hollow cubes. The prepared CuS@SnS2p-n heterostructure hollow cubes showed an improved photocatalytic CO2 reduction activity compared with the bare CuS and SnS2 control samples. The p-n heterojunction formed between SnS2 and CuS as well as its hollow structure enhanced the charge carrier separation efficiency and the light absorption capacity of the hybrid catalyst. Furthermore, after the decoration of Au nanoparticles, the formed Schottky junction further discouraged the charge carrier recombination. Thus, the cooperative p-n heterojunction and Schottky junction greatly facilitated photocatalytic CO2 reduction, and exhibiting the maximum CO and CH4 yields of 140.1 and 77.5 μmol g−1 h−1, respectively. This work presents an efficient design of high-performance catalysts for photocatalytic CO2 reduction.

A novel ratiometric electrochemical sensor based on AuNPs decorated MIL-101(Fe) for simultaneously monitoring typical EDCs in milk

It is challengeable for traditional electrochemical sensors to determine EDCs in food samples due to inadequate reproducibility. Herein, a novel ratiometric electrochemical sensor for monitoring two typical EDCs referred to 17β-estradiol (E2) and bisphenol S (BPS) was developed. Electrodeposition method was utilized for facile decoration of Au nanoparticles (AuNPs) on MIL-101(Fe) to obtain AuNPs@MIL-101(Fe) composite as sensing material. In contrast to common ratiometric approaches, the Fe signal supplied by MIL-101(Fe) was expediently and innovatively adopted as the internal reference tag instead of fixing electroactive molecules. Furthermore, benefited from the synergistic effect of MIL-101(Fe) and AuNPs, AuNPs@MIL-101(Fe) composite exhibited remarkably enhanced electrochemical activity, resulting in strengthened Fe reference signal and facilitated oxidation process of EDCs. With the rise of EDCs’ concentration, the current response of EDCs gradually increased while the Fe signal almost kept constant. Thus, a new ratiometric electrochemical sensor was successfully developed with a wide linear range of 0.039–7.80 µM for EDCs as well as low LOD of 9.8 nM for E2 and 11.2 nM for BPS. Finally, the newly constructed sensor was achieved in evaluating the two targets in milk samples. The developed sensor exhibited high reproducibility, stability, sensitivity and practicability, providing a new idea for constructing ratiometric electrochemical sensors and a new method for EDCs detection.

Improved NH3 Gas Sensing Performance of Femtosecond‐Laser Textured Silicon by the Decoration of Au Nanoparticles

Improved NH₃ Gas Sensing Performance of Femtosecond‐Laser Textured Silicon by the Decoration of Au Nanoparticles

Facile fabrication of Au nanoparticles loaded Ce doped ZnO nanorods for efficient catalytic and photocatalytic decomposition of toxic pollutants in water

Plasmonic Au nanoparticles (NPs) have been deposited onto Ce doped ZnO nanorods prepared through wet chemical route to enhance their photodecomposition performance. The catalytic and photocatalytic performances were evaluated using a series of model pollutants such as 4-nitrophenol, antibiotic levofloxacin, cationic and anionic dyes under sunlight illumination. Various characterization tools such as XRD, Raman, FESEM, TEM, SAED, EDX, XPS, PL and UV–vis spectroscopy were used to examine the structure and physico-chemical properties of the fabricated photocatalysts. XRD, TEM, SAED, EDX, XPS and Raman analyses confirmed the existence of Ce doped ZnO and Au nanostructures while UV–visible absorption studies revealed the presence of SPR of Au NPs in the visible region. The results illustrated that decoration of Au NPs on Ce doped ZnO nanorods makes them outstanding catalyst as well as photocatalyst compared to pure Ce doped ZnO nanorods. The plasmonic nanohybrids with higher Au concentration exhibited superior degradation capability towards reduction and detoxification of 4-NP, decomposition of antibiotic levofloxacin and synthetic dyes, respectively. In addition, detailed study of possible mechanisms behind 4-NP reduction and photodegradation process have been explored. Furthermore, the quenching experiments elucidating ·O2- radicals as the main active species in the degradation mechanism have also been discussed. Moreover, the prepared Ce doped ZnO-Au hybrid plasmonic nanorods maintained high stability and stunning photoactivity even after four cycles which highlights it as a promising material for wastewater treatment.

SERS monitoring of methylene blue degradation by Au-Ag@Cu2O-rGO nanocomposite

A combination of multiple materials effectively improves and enhances the performance of the materials. Thus, a gold-silver@cuprous oxide (Au-Ag@Cu2O)-reduced graphene oxide (rGO) structure was designed and fabricated. We decorated the Au nanoparticles (NPs) on the Ag@Cu2O-rGO composite surface by a redox reaction to form a Au-Ag@Cu2O-rGO structure with two noble metals attached to a Cu2O semiconductor. A comparable Au-Ag@Cu2O structure was also fabricated. After decorating Au NPs into the Ag@Cu2O-rGO composite, the Au-Ag@Cu2O composite structure was loosened, and the surface and interior of the Cu2O shell were decorated with Au and Ag NPs. Moreover, the addition of Au NPs resulted in a proper surface plasmon resonance effect and a significant broadening of the absorption range. The loose structure increased the adsorption of the probe molecules, which increased the surface-enhanced Raman scattering (SERS) intensity. In addition, the fabricated Au-Ag@Cu2O-rGO exhibited excellent catalytic reduction of methylene blue (MB) with sodium borohydride (NaBH4). Therefore, the SERS-based monitoring of the MB degradation was obviously improved.

Whole urine-based multiple cancer diagnosis and metabolite profiling using 3D evolutionary gold nanoarchitecture combined with machine learning-assisted SERS

To develop onsite applicable cancer diagnosis technologies, a noninvasive human biofluid detection method with high sensitivity and specificity is required, available for classifying cancer from the normal group. Herein, a three-dimensional evolutionary gold nanoarchitecture (3D-EGN) is developed by forming Au nanosponge (AuS) on a 96-well plate, followed by a decoration of Au nanoparticles (AuNPs) evolved with Au nanolamination (AuNL) for high-throughput urine sensing in liquid phase. The 3D-EGN exhibits not only strong electromagnetic field generated from numerous hotspot regions between AuNPs and further enhanced light scattering from multigrain boundaries after lamination process, but also highly volumetric field due to nanoporous structure of AuS, which is advantageous for sensitive liquid-phase SERS detection. SERS activity of the 3D-EGN platform is characterized using malachite green, showing a limit detection of 1.23 × 10−9 M in liquid phase, and excellent uniformities both within single well and well-to-well with relative standard deviation (RSD) values of about 10%. The 3D-EGN platform has been demonstrated for the detection of whole clinical human urine samples, proving effective molecular sensing in the presence of Brownian motion from liquid medium. Subsequently, cancer metabolite candidates are investigated to verify the metabolic alternations of multicancer, including pancreatic, prostate, lung, and colorectal cancers, simultaneously classifying them into five different groups, including normal with an accuracy of 95.6%, using machine-learning methods. The integration of nanomaterials with the conventional clinical platform provides rapid and high-throughput multicancer diagnostic system and opens a new era for noninvasive diseases diagnosis using clinical human biofluids.

Improved NH3 Gas Sensing Performance of Femtosecond‐Laser Textured Silicon by the Decoration of Au Nanoparticles

The escalating environmental concerns have stimulated the demand for NH3 gas sensors, which are indispensable for real‐time data collection in pollution monitoring. To address this need, optimized NH3 sensor based on femtosecond‐laser textured silicon decorated with Au nanoparticles (Au‐NP) is designed. The morphologies and microstructures of the fabricated samples are characterized by scanning electron microscopy (SEM) and X‐ray diffraction (XRD) technologies. The gas‐sensing results demonstrated that the modification of Au‐NPs significantly enhances the NH3 gas‐sensing performances. Specifically, the sensor based on the textured silicon decorated with Au NPs exhibits a remarkable response of 16.02% toward 20 ppm NH3, which is 4.7 times higher than that of the pristine textured silicon gas sensor at room temperature. In addition, it also demonstrates shortened response and recovery time (26 s/98 s), showing good selectivity and long‐term availability. The enhanced NH3‐sensing mechanism of the sensor is elucidated, mainly due to the synergistic effect of textured silicon and Au NPs. These contribute to the development of portable, wearable, and intelligent sensor equipment.

Steering the Reconstruction of Oxide-Derived Cu by Secondary Metal for Electrosynthesis of n-Propanol from CO.

As fuel and an important chemical feedstock, n-propanol is highly desired in electrochemical CO2/CO reduction on Cu catalysts. However, the precise regulation of the Cu localized structure is still challenging and poorly understood, thus hindering the selective n-propanol electrosynthesis. Herein, by decorating Au nanoparticles (NPs) on CuO nanosheets (NSs), we present a counterintuitive transformation of CuO into undercoordinated Cu sites locally around Au NPs during CO reduction. In situ spectroscopic techniques reveal the Au-steered formation of abundant undercoordinated Cu sites during the removal of oxygen on CuO. First-principles accuracy molecular dynamic simulation demonstrates that the localized Cu atoms around Au tend to rearrange into disordered layer rather than a Cu (111) close-packed plane observed on bare CuO NSs. These Au-steered undercoordinated Cu sites facilitate CO binding, enabling selective electroreduction of CO into n-propanol with a high Faradaic efficiency of 48% in a flow cell. This work provides new insight into the regulation of the oxide-derived catalysts reconstruction with a secondary metal component.

Au decorated chemically exfoliated g-C3N4 as highly efficient visible light catalyst for hydrogen production

The demand for photocatalytic hydrogen production through water splitting is continuously increasing as the world is seeking cleaner and sustainable energy solutions. Herein, we report a comparative study of the as-fabricated Bulk g-C3N4 (BCN), chemically exfoliated g-C3N4 (ECN) and Au-decorated chemically exfoliated g-C3N4 (Au/ECN) photocatalysts for visible light-driven catalytic hydrogen production. To understand the structural, morphological, chemical, and electronic properties of the as-fabricated photocatalysts, XRD, TEM, Raman, PL, XPS, FTIR, UV and EPR analysis was performed. The as-prepared Au/ECN photocatalyst revealed exceptional visible light catalytic performance by producing 410 μmol·g−1 of hydrogen, which is 27.3- and 9.3-fold enhanced compared to those of the CN (15 μmol·g−1) and ECN (44 μmol·g−1) photocatalysts, respectively. This improved visible light-driven catalytic performance of the Au/ECN photocatalyst for hydrogen production is due to the enhanced specific surface area via the chemically exfoliated layered sheets, promoted light absorption due to the decrease in band gap via the effect of surface plasmon resonance attributable to decorated Au nanoparticles, and efficient separation of charge carriers at the interfacial contact. The photocatalytic recyclable experiments indicate excellent stability of the Au/ECN photocatalyst for H2 evolution. These findings reveal the effect of chemical exfoliation and Au decorating on the catalytic efficiency of g-C3N4-based photocatalysts, revealing potential functions for green hydrogen production under the standard visible light illumination.

In situ laser-assisted decoration of Au nanoparticles on 3D porous graphene for enhanced 2-CEES sensing

In situ Au decorated laser-induced graphene (LIG/Au) behaves as an effective near-room-temperature 2-chloroethyl ethyl sulfide (2-CEES) sensor. It exhibits an enhanced response of 7.85‰ to 1.0 ppm 2-CEES, which is twice as that of pure LIG.

Resonance-Assisted Surface-Enhanced Raman Spectroscopy Amplification on Hierarchical Rose-Shaped MoS2/Au Nanocomposites.

Surface-enhanced Raman spectroscopy (SERS) has emerged as a highly sensitive trace detection technique in recent decades, yet its exceptional performance remains elusive in semiconductor materials due to the intricate and ambiguous nature of the SERS mechanism. Herein, we have synthesized MoS2 nanoflowers (NFs) decorated with Au nanoparticles (NPs) by hydrothermal and redox methods to explore the size-dependence SERS effect. This strategy enhances the interactions between the substrate and molecules, resulting in exceptional uniformity and reproducibility. Compared to the unadorned Au nanoparticles (NPs), the decoration of Au NPs induces an n-type effect on MoS2, resulting in a significant enhancement of the SERS effect. This augmentation empowers MoS2 to achieve a low limit of detection concentration of 2.1 × 10-9 M for crystal violet (CV) molecules and the enhancement factor (EF) is about 8.52 × 106. The time-stability for a duration of 20 days was carried out, revealing that the Raman intensity of CV on the MoS2/Au-6 substrate only exhibited a reduction of 24.36% after undergoing aging for 20 days. The proposed mechanism for SERS primarily stems from the synergistic interplay among the resonance of CV molecules, local surface plasma resonance (LSPR) of Au NPs, and the dual-step charge transfer enhancement. This research offers comprehensive insights into SERS enhancement and provides guidance for the molecular design of highly sensitive SERS systems.

Fabrication of large-area Au nanoparticle decorated ZnO@ZIF-8 core-shell heterostructure nanorods for ppb-level NO2 gas sensing at room temperature

Metal-organic frameworks based heterostructures have gained wide attention recently for various applications. Specifically metal oxide and zeolitic imidazolate framework-8 (ZIF-8) nanocomposites have been synthesized for gas sensing with reasonable performance. In this work, large-area Au nanoparticle (NP) decorated ZnO@ZIF-8 core-shell heterostructure nanorods (NRs) are synthesized for ppb-level UV-activated NO2 sensing at room temperature. Large-area ZnO NRs are first grown and ZIF-8 shells are subsequently formed on ZnO with the result of various types of ZnO@ZIF-8 NRs. The ZnO@3ZIF-8 NRs have the highest response and Au NPs are finally decorated on the NR surfaces. The ZnO@3ZIF-8/Au sensor shows high responses of 260% and 34700% toward 0.05 and 3.75 ppm NO2 gas, respectively. An excellent linear sensitivity of 95.1 ppm–1 has been achieved and the estimated lowest detection limit is 0.3 ppb. It is noteworthy that the linear dynamic range is extended by at least 8 times after ZIF-8 addition and the sensitivity is enhanced by 12 times after Au NP decoration. The sensor is also highly NO2 selective against other gases including NO, NH3, SO2, CO, CH3OH, CH2O, C2H5OH, and C3H6O. The excellent performance of the ZnO@3ZIF-8/Au sensor shows good potential for environmental NO2 sensing.

Duple charge separation and plasmonically enriched DSSC and piezo-photocatalytic efficacy of Au anchored perovskite Gd3+:BiFeO3 nanospheres

Enhancing the solar-physical conversion efficacy ability of the nanomaterials is an essential for real-time implementation. We report the enhanced solar-physical efficiency of the BiFeO3 nanospheres via Gd3+ doping and Au nanoparticles decoration. Initially, we have obtained the Bi1-xGdxFeO3 nanospheres were attained via a simple solvothermal technique and then citrate reduction of Au was conducted. Obtained perovskite BiFeO systems were studied for the Gd3+ doping, crystalline phase and elemental purity using the XRD and XPS techniques. Transmission electron microscope had revealed the ∼400 nm sized BiFeO3 nanospheres. Optical absorption spectrum revealed the enhanced visible photon absorption occurring in BiFeO3 for both Gd3+ doping and Au decoration. The bandgap values of pristine, 1%, 3% and 5% Gd3+ doped in BiFeO3 are 2.2 eV, 2.19 eV, 2.17 eV and 2.12 eV, respectively. Conducted photoluminescence revealed the dual electron trapping occurring in BiFeO3 via Gd3+ ions and Au nanoparticles. LED light assisted 72% of piezo-photocatalytic degradation efficiency of Tetracycline is achieved with Bi0 95Fe0 05O3/Au, whereas the photo catalytic is only 65% and piezo catalytic efficiency is 58%. In recyclable studies the Bi0.95Gd0.05FeO3/Au had shown the consistent piezo-photocatalytic efficiency for 3 reaction cycles. Further, fabricated DSSC studies revealed that near 30 % enhanced solar photovoltaic efficiency for Bi0 95Fe0 05O3/Au (η = 6.5%) solar cells on par to the pristine BiFeO3 (η = 5.02%).

Comprehensive study of formaldehyde gas sensing performance of a GTO thin film incorporated with gold nanoparticles

There are lots of semiconducting metal oxides (SMOs) which have been used for detecting volatile organic compounds (VOCs), such as ZnO, SnO2, NiO, Ga2O3, WO3, ZnO, In2O3, etc. SnO2 is a widespread used SMO to develop a variety of chip to detect VOCs. In this work, a novel SMO gas sensor based on the combination of SnO2 material with a little proportion of wide bandgap (4.9 eV) Ga2O3 material, denoted as GTO, is proposed to detect formaldehyde (HCHO) gas. The studied sensor is synthesized by a radio-frequency (RF) sputtered GTO thin film and vacuum thermal evaporated gold (Au) nanoparticles (NPs) and treated with a post annealing. The related material properties are analyzed by X-ray Diffraction (XRD), X-ray photoelectron spectroscopy (XPS), energy-dispersive X-ray spectroscopy (EDS), atomic force microscopy (AFM), high-resolution scanning electron microscopy (HRSEM), and transmission electron microscopy (TEM). The decoration of Au NPs on the surface of GTO thin film causes a significant improvement on sensing performance. A high sensing response of 275 accompanied with a response (recovery) time of 16 s (11 s) under 20 ppm HCHO/air ambiance and an extremely low content of 50 ppb HCHO/air with a sensing response of 21 are obtained at 300 ℃. Furthermore, the studied sensor performs good selectivity, repetitivity, and long-term (120 days) stability.

Decoration of Au Nanoparticles over LaFeO3: A High Performance Electrocatalyst for Total Water Splitting.

Electrocatalytic water splitting has emerged as a promising approach for clean and sustainable hydrogen production. The LaFeO3 perovskite structure exhibits intriguing properties such as mixed ionic-electronic conductivity, high stability, and abundant active sites for electrocatalysis. However, its OER and HER activities are limited by the sluggish kinetics of these reactions. To overcome this limitation, Au nanoparticles (NPs) are decorated onto the surface of LaFeO3 through a facile synthesis method. The Au NPs on the LaFeO3 surface provide additional active sites for water splitting reactions, promoting the adsorption and activation of water molecules. The presence of Au enhances the charge transfer kinetics via the heterostructure between Au NPs and LaFeO3 and facilitates electron transport during the OER and HER process. The catalyst requires only 318 and 199 mV as overpotential to attain a 50 mA cm-2 current density in 1 M KOH solution. Our results demonstrate that the Au@LaFeO3 catalyst exhibits significantly improved electrocatalytic activity compared to pure LaFeO3 and other catalysts reported in the literature. The enhanced performance is attributed due to the synergistic effects between Au NPs and LaFeO3, including an increased surface area, improved conductivity, and optimized surface energetics. Overall, the Au-decorated LaFeO3 catalyst presents a promising candidate for efficient electrocatalytic water splitting, providing a pathway for sustainable hydrogen production. The insights gained from this study contribute to the development of advanced catalysts for renewable energy technologies and pave the way for future research in the field of electrochemical water splitting.

Plasmon resonance-enhanced superior 2D MoS2 photodetector via single-layer gold nanoparticle film with ultra-high area density

Molybdenum disulfide (MoS2) has been considered as a promising candidate material for photodetectors due to its unrivaled transistor behavior and strong light absorption. However, due to the ultra-thin nature of monolayer or few-layer MoS2, it exhibits a low optical cross-section, resulting in a very weak light–matter interaction and accordingly limiting the photoelectric conversion efficiency. In this work, we report a facile method to prepare single-layer gold (Au) nanoparticles with ultra-high area density according to the annealing of thin Au films. By transferring the single-layer Au nanoparticle film onto a prefabricated MoS2 photodetector, we demonstrate a photodetector with a responsivity as high as 1120 A W−1. Moreover, it is found that the response time is not affected by the Au nanoparticle decoration. This method provides an easy but effective way to fabricate high-performance two-dimensional material-based photodetectors.

Determination of methotrexate in plasma and environmental samples using an electrochemical sensor modified by UiO66-NH2/mesoporous carbon nitride composite and synergistic signal amplification with decorated AuNPs

Electrochemical methods have low toxicity, fast response and, easy operation. By modifying electrochemical sensors with a conductive and porous modifier, their sensitivity and selectivity can be improved. Nanomaterials with new and extraordinary properties are a new approach in science and especially in electrochemical sensors. In this study, UiO66-NH2/mesoporous carbon nitride (M − C3N4) composite provides a porous structure for decorated Au nanoparticles (AuNPs) to prepare a potent modifier for carbon paste electrode (CPE). Due to environmental toxicity of methotrexate, its sensitive, fast and, low-cost determination in workplace environments is of great interest. So, the modified CPE was applied as a sensitivity analysis approach for methotrexate in plasma samples. Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) were used as techniques to optimize the analysis and measurement of methotrexate. To measure this drug, several effective parameters were optimized and a calibration curve was drawn under optimal conditions. The calibration curve showed a linear range from 0.5 to 150 μM with a detection limit of 0.15 μM for methotrexate. Examining the repeatability of the response of one electrode and multiple electrodes under optimal conditions shows the high precision of the developed method. Finally, this developed method based on UiO66-NH2/M-gC3N4/AuNPs|CPE was used to determine the methotrexate in the plasma sample using the standard addition method.

Nanogold-decorated reduced graphene oxide for catalytic hydrogenation of 4-nitrophenol

The current work focuses on the efficacious synthesis of Au nanoparticles (NPs) decorated on reduced graphene oxide (RGO) sheets and evaluating and comparing the catalytic efficiency of the latter with graphene oxide (GO) and reduced graphene oxide (RGO) for the hydrogenation of 4-nitrophenol (4-NP). 4-NP is one of the most hazardous and widely investigated nitro compounds. Here, we report a single-step co-reduction approach for synthesizing AuRGO using hydrazine monohydrate as a reducing agent. X-ray diffraction (XRD) patterns of prepared samples confirmed the formation of GO, RGO, and AuRGO. Raman analysis gave insight into the structure and defects of prepared samples. The various oxygen-containing moieties are identified using Fourier transform infrared (FTIR) spectra and confirmed the loss of these functional groups during the reduction of GO into RGO. UV absorption analysis is carried out and is also reinforced by the finite difference time domain (FDTD) simulation studies. X-ray photoelectron spectroscopy (XPS) analysis yielded quantitative information regarding the reduction of GO into RGO and the decoration of zerovalent Au NPs on the RGO surface. Thermogram of the prepared samples manifests the thermal stability of the samples. Field emission scanning electron microscope (FESEM) and transmission electron microscopy (TEM) images depicted the morphology of GO, RGO, and AuRGO. The catalytic efficiency of AuRGO is tested by reducing 4-nitrophenol (4-NP) in the presence of sodium borohydride. AuRGO has shown enhanced catalytic efficiency compared to GO and RGO.