Catalytic Active Sites Research Articles

Air plasma activation of catalytic sites within MXene nanosheets for oxygen evolution and urea oxidation catalysis

Atmospheric pressure medium–blocked discharge plasma modified the hydroxyl and fluorine groups on the dispersed surface of MXene as well as the valence states of metal ions to promote electrocatalytic reactions efficiently. The plasma-treated samples maintain the nature and macroscopic morphology of the open active sites of the original framework structure, whereas the valence and electronic structures of the metal centers are altered. When dielectric barrier discharge plasma-modified MXene is used to assemble a monolithic hydrolysis device for hydrogen evolution reaction (HER)||oxygen evolution reaction (OER), the current density is up to 100 mA/cm2 at 2.1 V (actual data without IR compensation). Furthermore, in urea-assisted water electrolysis HER||urea oxidation reaction, the voltage is only 1.8 V, which is 300 mV lower than that of HER||OER. Meanwhile, the electrocatalytic system can operate continuously with high durability for more than 100 h. This work provides an effective electrocatalyst not only for efficient hydrogen production but also for urea wastewater purification.

Au@AgPt core/cage nanoframes as photothermal catalyst for enhanced NIR-induced 4-nitrophenol reduction

The selection and optimization of catalysts have been a subject of considerable research interest in recent decades. Bimetallic and multimetallic nanocatalysts, comprised of plasmonic and catalytic components, have recently emerged as a promising approach to achieving high catalytic performance due to synergistic effects. In this study, an Au@AgPt core/cage nanoframe has been successfully fabricated. It features a controllable hollow silver-platinum alloy nanoframe with an in-built plasmonic gold nanorod, serving as a plasmon-enhanced photothermal catalyst for the reduction of 4-nitrophenol (4-NP). This well-designed trimetallic nanostructure exhibits a unique core-cage nanoframes structure and surface roughness, offering advantages in both composition and structure. The LSPR-excited local heating effect and hot-electron generation, as well as the intrinsic catalytic active sites, work synergistically and are highly beneficial for temperature-sensitive reaction of 4-NP reduction. Experimental results have shown that the optimized nanocatalysts of Au@AgPt-4, featuring an optimal Pt content and robust photothermal performance, display stable photothermal catalytic properties and the best photothermal catalytic performance compared with other nanostructures, completing the reduction reaction within approximately one minute. This study provides a rational design of nanoscale materials with plasma-enhanced properties, which can help to inspire further catalyst design and optimization.

Surface decoration of plasmonic Ag nanospheres for enhanced visible light photocatalysis of BiVO4

The industrial concern of producing benzaldehyde (BD) more efficiently is the key aspect of this work. Therefore, the oxidation of benzyl alcohol (BA) by photocatalytic route was chosen. The amoeba-like BiVO4 (BV) particles were synthesized by co-precipitate method since it gives higher yield when compared to other methods and silver nanoparticles were decorated over its surface by photo deposition method. Due to surface plasmon resonance (SPR effect), the decorated samples showed enhanced optoelectronic properties. The band edge positions shifted to higher energy levels profitably paving the way for the production of superoxide radicals (•O2−) effectively. The optimal catalyst material was engineered in such a way that it would facilitate the production of both •O2− and BA* radicals and inhibits the production of BD* radical. The decorated silver nanoparticles aided in increasing the surface area and the number of catalytic active sites, therein a 4.7-fold increase in benzaldehyde yield was achieved when compared to pure BV. Since monoclinic BV possesses piezoelectric property, the use of ultrasound in the reaction medium boosted the efficiency of the reaction and henceforth a maximum conversion of 88.29 % was obtained. Hydrogen peroxide formed as a byproduct, adds commercial value to this reaction.

Kinetic study of p-nitrophenol degradation with zinc oxide nanoparticles prepared by sol–gel methods

Three zinc oxides (ZnO A, B, C) with similar spherical morphology but different sizes are synthesized by sol–gel methods. A kinetic study is carried out on the photocatalytic activity of these three ZnO, through the degradation of p-nitrophenol (PNP). A mathematical model is developed and the rate constants of the three catalysts are determined. To understand the parameters influencing the kinetics, the catalysts are reduced to the surface of an isolated particle (assuming perfect dispersion conditions where all catalytic active sites are available) whose size is determined by X-ray diffraction (XRD) and transmission electron microscopy (TEM). However, by considering the real case (not a perfect dispersion), it appears that the size of the aggregates induced by the synthesis methods play a more important role in the catalytic activity of the three ZnO samples than defects. A discussion on the formation of these aggregates highlights the importance of the synthesis parameters, like the solvent or the surfactant used to obtain a high dispersion. The dispersion plays a crucial role in photocatalytic efficiency, with kinetics three times higher for the catalyst with the best dispersion. Also, as shown by photoluminescence and X-ray photoelectron spectroscopy (XPS), the type and amount of defects play an important role in the photocatalytic performance. ZnO A and B show a defect peak at 620 nm whereas ZnO C shows a defect peak at 680 nm, suggesting a different type of defect on the surface of the catalyst that reduces the photocatalytic performance. Electron paramagnetic resonance (EPR) measurements are performed to identify the type of radicals involved in PNP degradation. The results show that the catalyst with the best dispersion produces the highest amount of hydroxyl radicals. Finally, photoluminescence and XPS analyses underline the type and the amount of defects for the three photocatalysts.

Advances on Single‐Atom‐Based Dual‐Site Photocatalysts: Fundamentals, Mechanisms, and Applications

Single‐atom catalysts (SACs) have emerged as leading‐edge research in the field of photocatalysis due to outstanding photocatalytic performance, maximum atomic utilization efficiency, and well‐defined catalytic active sites. However, the singular functionality of active sites in SACs restricts their applications in complex redox reactions involving multiple intermediates and reaction pathways. To circumvent this limitation, a second site comprising single atoms (SA), alloys, clusters, or nanoparticles is proposed to establish SA‐based dual‐site photocatalysts (SA DSPs). While maintaining 100% atomic utilization, the second site and site–site collaboration endow SA DSPs with superior photocatalytic activities to surpass those of SACs. In this review, the latest investigations on SA DSPs featuring diverse compositions, electronic and geometric configurations, site–site collaboration, and metal–support interactions are summarized. Thereafter, the mechanisms underlying enhanced photocatalytic activities are elucidated regarding the roles of the dual sites in charge‐carrier dynamics and surface reactivity. Furthermore, the state‐of‐the‐art applications in photocatalytic hydrogen evolution, CO2 reduction, and methane oxidation, etc., over SA DSPs are discussed. It is anticipated that this review will offer insights into precise control and design of dual sites in photocatalysts, thereby advancing photocatalysis toward commercial viability.

Advanced Development of In situ Characterization Technique for Electrocatalytic Hydrogen Evolution Reaction

AbstractHydrogen evolution reaction (HER) from water splitting using renewable energy provides a promising solution to the global energy crisis and environmental problems. However, the lack of in‐depth understanding of the reaction mechanism and clear identification of the catalytic active site has hindered the further development of low‐cost, high‐performance, and long‐life efficient electrocatalysts. Through in situ characterization techniques, the activity and stability of catalysts can be monitored in real‐time, track the structural evolution of catalytic reaction intermediates, and obtain a deep understanding of catalytic reaction mechanism, so as to feedback and guide the development and utilization of the catalyst. In this review, advanced development of in situ characterization techniques in electrocatalytic HER in recent years is summarized. In situ spectroscopy can be used to track the behavior of reaction intermediates such as adsorption, desorption, and structural evolution at the molecular level to reveal the electrocatalytic HER mechanism. The imaging techniques can be used to observe the evolution of material structure during HER in situ, which provides valuable information for the understanding of visualization of catalytic hydrogen evolution at atomic level. This review contributes to theadvanced development of in situ characterization technique for electrocatalytic HER.

Iron-doping regulated light absorption and active sites in LiTaO3 single crystal for photocatalytic nitrogen reduction

In contrast to research on active sites in nanomaterials, lithium tantalate single crystals, known for their exceptional optical properties and long-range ordered lattice structure, present a promising avenue for in-depth exploration of photocatalytic reaction systems with fewer constraints imposed by surface chemistry. Typically, the isotropy of a specific facet provides a perfect support for studying heteroatom doping. Herein, this work delves into the intrinsic catalytic sites for photocatalytic nitrogen fixation in iron-doped lithium tantalate single crystals. The presence of iron not only modifies the electronic structure of lithium tantalate, improving its light absorption capacity, but also functions as an active site for the nitrogen adsorption and activation. The photocatalytic ammonia production rate of the iron-doped lithium tantalate in pure water is maximum 26.95 μg cm−2 h−1, which is three times higher than that of undoped lithium tantalate. The combination of first-principles simulations with in situ characterizations confirms that iron doping promotes the rate-determining step and changes the pathway of hydrogenation to associative alternating. This study provides a new perspective on in-depth investigation of intrinsic catalytic active sites in photocatalysis and other catalytic processes.

Co-pyrolysis of fly ash with sewage sludge for PCDD/F removal.

Fly ash generated from municipal waste incineration (MWI) contains various toxic substances, and it has to be properly treated before disposal or reuse. Water washing and thermal pyrolysis can improve the destruction efficiency of PCDD/Fs in fly ash generated from municipal solid waste incinerators. Since sulfur oxides and nitrogen compounds generated by the heating of the sewage sludge poison the catalytic active sites for PCDD/Fs formation on fly ash surface, co-pyrolysis of fly ash with sewage sludge effectively inhibits precursor formation and de novo synthesis reaction, resulting in the great reduction of PCDD/F formation. The results of the pyrolysis at 350 °C show that the PCDD/Fs removal efficiencies based on mass concentration are over 99%. The results at 350 °C of different reaction times show that the reaction time of 10 min is sufficient to reach the European End of Waste criteria (≤ 20 pg TEQ/g) when the ratio of fly ash/sewage sludge is controlled at 1:1.

Comparative study of organic removal by pre-adsorption oxidation and synchronous adsorption oxidation processes: Performance and mechanism

Both adsorption and oxidation occur and contribute to organics removal in carbonaceous materials based advanced oxidation processes, while the correction of adsorption and oxidation, and the role of adsorption in the veritable removal of organic are not clear. Herein, we investigated the performance of carbamazepine (CBZ) removal by peroxymonosulfate (PMS) activated by magnetic Fe-doped biochar through two models of pre-adsorption oxidation and synchronous adsorption oxidation processes. The adsorption process was better fitted by pseudo-second-order kinetic model and the adsorption mechanism was obtained by comprehensive analysis of equilibrium adsorption capacities, surface functional groups, specific surface area, pore volume, and ID/IG value. It is noted that pre-adsorption highly inhibited the further oxidation of CBZ in 0.5Fe@LSBC700/PMS system due to the occupied catalytic active sites. Total CBZ removal in pre-adsorption oxidation (45 %) was inferior to synchronous adsorption oxidation (∼100 %), as well as the veritable CBZ oxidation removal of 27 % for pre-adsorption oxidation vs ∼100 % in synchronous adsorption oxidation at 30 min. Oxidation degradation of CBZ based on radical oxidation was identified by quenching experiments and electron paramagnetic resonance measurements. This work is conducive to identifying the role of adsorption during the removal of organics in the adsorption-oxidation process, as well as veritable adsorption and oxidation removal of organics.

Metal Hydrogen-Bonded Organic Frameworks as Open Lewis Acid Catalysts for Two Types of CO2 Transformations.

Efficient and multiple CO2 utilization into high-value-added chemicals holds significant importance in carbon neutrality and industry production. However, most catalysis systems generally exhibit only one type of CO2 transformation with the efficiency to be improved. The restricted abundance of active catalytic sites or an inefficient utilization rate of these sites results in the constraint. Consequently, we designed and constructed two metal hydrogen-bonded organic frameworks (M-HOFs) {[M3(L3-)2(H2O)10]·2H2O}n (M = Co (1), Ni (2); L = 1-(4-carboxyphenyl)-1H-pyrazole-3,5-dicarboxylic acid) in this research. 1 and 2 are well-characterized, and both show excellent stability. The networks connected by multiple hydrogen bonds enhance the structural flexibility and create accessible Lewis acidic sites, promoting interactions between the substrates and catalytic centers. This enhancement facilitates efficient catalysis for two types of CO2 transformations, encompassing both cycloaddition reactions with epoxides and aziridines to afford cyclic carbonates and oxazolidinones. The catalytic activities (TON/TOF) are superior compared with those of most other catalysts. These heterogeneous catalysts still exhibited high performance after being reused several times. Mechanistic studies indicated intense interactions between the metal sites and substrates, demonstrating the reason for efficient catalysis. This marks the first instance on M-HOFs efficiently catalyzing two types of CO2 conversions, finding important significance for catalyst design and CO2 utilization.

Bridging Atom Engineering for Low-Temperature Oxygen Activation in a Robust Metal-Organic Framework.

Achieving active site engineering at the atomic level poses a significant challenge in the design and optimization of catalysts for energy-efficient catalytic processes, especially for a reaction with two reactants competitively absorbed on catalytic active sites. Herein, we show an example that tailoring the local environment of cobalt sites in a robust metal-organic framework through substituting the bridging atom from -Cl to -OH group leads to a highly active catalyst for oxygen activation in an oxidation reaction. Comprehensive characterizations reveal that this variation imparts drastic changes on the electronic structure of metal centers, the competitive reactant adsorption behavior, and the intermediate formation. As a result, exceptional low-temperature CO oxidation performance was achieved with T25(Temperature for 25 % conversion)=35 °C and T100 (Temperature for 100 % conversion)=150 °C, which stands out from existing MOF-based catalysts and even rivals many noble metal catalysts. This work provides a guidance for the rational design of catalysts for efficient oxygen activation for an oxidation reaction.

Bridging Atom Engineering for Low‐Temperature Oxygen Activation in a Robust Metal–Organic Framework

AbstractAchieving active site engineering at the atomic level poses a significant challenge in the design and optimization of catalysts for energy‐efficient catalytic processes, especially for a reaction with two reactants competitively absorbed on catalytic active sites. Herein, we show an example that tailoring the local environment of cobalt sites in a robust metal–organic framework through substituting the bridging atom from −Cl to −OH group leads to a highly active catalyst for oxygen activation in an oxidation reaction. Comprehensive characterizations reveal that this variation imparts drastic changes on the electronic structure of metal centers, the competitive reactant adsorption behavior, and the intermediate formation. As a result, exceptional low‐temperature CO oxidation performance was achieved with T25(Temperature for 25 % conversion)=35 °C and T100 (Temperature for 100 % conversion)=150 °C, which stands out from existing MOF‐based catalysts and even rivals many noble metal catalysts. This work provides a guidance for the rational design of catalysts for efficient oxygen activation for an oxidation reaction.

From density functional theory to machine learning predictive models for electrical properties of spinel oxides.

This work focuses on predicting and characterizing the electronic conductivity of spinel oxides, which are promising materials for energy storage devices and for the oxygen evolution and oxygen reduction reactions due to their attractive properties and abundance of transition metals that can act as active sites for catalysis. To this end, a new database was developed from first principles, including band structure and conductivity properties of spinel oxides, and machine learning algorithms were trained on this database to predict electronic conductivity and band gaps based solely on the compositions. The models developed in this study are scaled from the quantum level up to a continuum conductivity model. The relatively small database used in this study allowed for accurate predictions of band gap and conductivity. By altering the composition of spinel oxides, the model was able to predict high conductivity for spinels with high nickel content and to match experimental trends for manganese cobalt spinels. The ability to predict material properties is especially important in energy conversion devices such as batteries and supercapacitors where redox reactions take place.

Cu single atoms mediated multiple active site reconfiguration to trigger Dual-pathway nonradical peroxymonosulfate activation process

Developing atomically dispersed metal sites is vital to enhance the activation of peroxymonosulfate (PMS). However, for catalyst systems where single atoms and nanoclusters coexist, how to identify the independent and synergistic effects of atomic sites and investigate the possible coexistence of multiple activation mechanisms still remains a great challenge. Herein, CuSA/CoOx-CeO2 catalysts with Cu single atoms and CoOx nanoclusters were fabricated for PMS activation. The introduction of Cu single atoms led to the reconstruction and diversification of catalytic active sites of CoOx-CeO2. The synergy between CoOx nanoclusters and neighboring Cu single atoms in CuSA/CoOx-CeO2 catalyst led to the 1O2 pathway of PMS activation, while the isolated Cu atom induced the Cu(III) oxidation pathway. The introducing of adjacent Cu single atoms caused the redistribution of the site charges in CoOx nanoclusters, which enhanced the charge transfer and promoted the adsorption and activation behavior of PMS molecules. During the evolution of 1O2, the synergistic effect of Cu single atoms and CoOx nanoclusters increased the stability of the reaction intermediate state (*OO*SO3), reducing the total Gibbs free energy change (ΔG) required for 1O2 formation. Compared with the cooperative site, the isolated Cu-O4 sites exhibited stronger charge transfer capacity to PMS molecules and were more conducive to the activation of the local substrate electronic structure, facilitating the formation and stabilization of Cu(III)–OH metastable intermediates. Overall, this study demonstrated the importance about the construction of multi-site induced multipath coexisting PMS activation system and the accurate identification of active sites.

Metal-acid synergistic catalysis accelerates the hydrogen borrowing amination of alcohols by confining Ru sites in Beta zeolite

Direct hydrogen transfer amination of alcohols with amines is an environmentally friendly and atom-economical route for the synthesis of N-alkylamines. Noble metal species are highly catalytic active sites, but the exorbitant price makes the urgency to boost the atom efficiency with stable recyclability. Herein, we demonstrated that encapsulation of Ru nanoparticles (NPs) within BEA zeolite through direct hydrothermal approach greatly promoted the catalytic efficiency in the N-alkylation of aromatic alcohols and amines under additive- and solvent-free conditions, resulting in the high yield (∼93 %), maximum turnover number (TON) of 12,822 and turnover frequency (TOF) of 9012 h−1, with stable recyclability and extendable substrate scope. The kinetic studies and in-situ characterizations revealed that the synergy of confined Ru NPs and adjacent acid sites of BEA zeolite significantly promoted the C–H bond activation in the rate-determining step of alcohol dehydrogenation into aldehydes. Besides, the acid sites also accelerated the condensation of aldehyde intermediates and anilines to promote the kinetic equilibrium, while the moderate strength of the Ru–H bond resulting from the confined Ru NPs is advantageous to balance the dehydrogenation and hydrogenation steps to reach the fascinating H-transfer process.

MOF-derived MnCe3.67C6Permeable microflower: A robust electrocatalyst for oxygen evolution reaction

To enhance the accessibility of hydrogen fuel production, there is a pressing need for the development of efficient catalysts possessing abundant catalytic active sites, robust stability, and a substantial surface area conducive to both the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). In this study, we present a novel electrocatalyst derived from a metal-organic framework (MOF) precursor, specifically MnCe3.67C6, synthesized through a cost-effective and straightforward pyrolysis process. This process involves the transformation of carefully designed porous spongy conjoined tapeworm like morphology at 973.15 K carburized temperature and which transform into conjoined nanowires when carburization temperature increases from 1073.15 to 1273.15 K into aggregated nanospheres, with the MOF serving as a carbon template. The structural, morphological, and compositional characteristics of the resulting MnCe3.67C6 catalyst were thoroughly investigated using techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). Remarkably, the MnCe3.67C6 catalyst exhibits outstanding OER activity, manifesting a significantly reduced potential of 231 mV at current density of 10 mAcm−2 in alkaline media, thereby facilitating efficient charge transfer. Furthermore, the fabricated MnCe3.67C6-700 electrocatalyst demonstrates a decreased Tafel slope of 68mVdec−1, indicative of a favorable kinetic mechanism for the resultant material. The electrochemical active surface increases considerably after fabrication of composite MnCe3.67C6-700 (Cdl = 77 mFcm−2) as compared to Mn–Ce/MOF (Cdl = 34 mFcm−2). Moreover, the higher OER activity is also complemented with extraordinary stability of MnCe3.67C6-700 that is capable of performing oxygen evolution reaction for more than 150 h, making it attractive candidate for the commercial utilization. Notably, the enhanced catalytic performance of MnCe3.67C6 can be attributed primarily to the well-dispersed cerium on the carbon surface, which provides an enlarged active surface area replete with catalytic sites, as well as the dynamic charge transfer of electrons depicted in XPS spectrum, thereby enhancing electrochemical properties and paving the way for future applications.

Porous CePO4@carbon composite derived from cerium-based metal–organic framework for the simultaneous detection of dopamine, uric acid, and acetaminophen

Cerium phosphate (CePO4) has attracted increasing attention in the field of electrochemistry. In this work, a mesoporous CePO4@carbon composite was successfully prepared via the high-temperature calcination method using cerium-based metal–organic framework (Ce-MOF) as a precursor. The obtained samples were characterized by powder X-ray diffraction (PXRD), Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), scanning electron microscopy (SEM), N2 adsorption–desorption technique, and X-ray photoelectron spectroscopy (XPS). The findings revealed that the in-situ pyrolysis of Ce-MOF generated uniform composite, which showed high electrical conductivity and plenty of catalytic active sites. These structural advantages of the composite were conductive to the electron transfer, substrate diffusion, and redox reactions. Thereafter, CePO4@carbon was developed to modify the commercially purchased glass carbon electrode (GCE: CHI 104) for simultaneous detection of dopamine (DA), uric acid (UA), and acetaminophen (APAP). The linear detection ranges for DA, UA, and APAP were 2.5–310.0 μM, 3.0–305.0 μM, and 2.5–617.0 μM, respectively. The detection limits (LOD) for DA, UA, and APAP were 0.009 μM, 0.016 μM, and 0.014 μM, respectively. Furthermore, the constructed electrode can be employed to detect the concentration of DA, UA, and APAP in real-samples. This work provides a method for manufacturing highly efficient CePO4 based materials for electrochemical sensing.

Queuosine biosynthetic enzyme, QueE moonlights as a cell division regulator.

In many organisms, stress responses to adverse environments can trigger secondary functions of certain proteins by altering protein levels, localization, activity, or interaction partners. Escherichia coli cells respond to the presence of specific cationic antimicrobial peptides by strongly activating the PhoQ/PhoP two-component signaling system, which regulates genes important for growth under this stress. As part of this pathway, a biosynthetic enzyme called QueE, which catalyzes a step in the formation of queuosine (Q) tRNA modification is upregulated. When cellular QueE levels are high, it co-localizes with the central cell division protein FtsZ at the septal site, blocking division and resulting in filamentous growth. Here we show that QueE affects cell size in a dose-dependent manner. Using alanine scanning mutagenesis of amino acids in the catalytic active site, we pinpoint residues in QueE that contribute distinctly to each of its functions-Q biosynthesis or regulation of cell division, establishing QueE as a moonlighting protein. We further show that QueE orthologs from enterobacteria like Salmonella typhimurium and Klebsiella pneumoniae also cause filamentation in these organisms, but the more distant counterparts from Pseudomonas aeruginosa and Bacillus subtilis lack this ability. By comparative analysis of E. coli QueE with distant orthologs, we elucidate a unique region in this protein that is responsible for QueE's secondary function as a cell division regulator. A dual-function protein like QueE is an exception to the conventional model of "one gene, one enzyme, one function", which has divergent roles across a range of fundamental cellular processes including RNA modification and translation to cell division and stress response.

Defect-rich CoRu alloy embedded in the porous carbon serving as highly-efficient and bifunctional electrocatalyst for overall water splitting over a wide pH range

Exploring highly-efficient and pH-universal overall water splitting electrocatalysts are critical but keep challenging. Herein, a highly-efficient, dual-function and pH-universal electrocatalyst consisting of CoRu alloy nanoparticles embedded in the carbon matrix (CoRu/C) was successfully synthesized through an acid etching-pyrolysis conversion process using ZIF-67 as a precursor. Benefiting from the rich crystal defects created during the alloy formation process that could serve as active catalytic sites and the optimized electronic structure, the as-obtained CoRu/C electrocatalyst required overpotentials of only 18 and 37 mV to reach a current density of 10 mA cm−2 for hydrogen evolution reaction (HER) and 184 and 170 mV for oxygen evolution reaction (OER) in 1.0 M KOH and 0.5 M H2SO4 aqueous solution, respectively. For practical application, the CoRu/C catalyst only needs a cell voltage of 1.49 and 1.45 V in a two-electrode overall water splitting system to achieve a current density of 10 mA cm−2 in alkaline and acidic medium, respectively. The present work paves a new way for the design and construction of efficient bifunctional electrocatalyst for overall water splitting, and would inspire widespread research interest in the field of energy storage and conversion.

A green perspective for the first electrochemical detection and application of balsalazide via recycled waste core-shell carbon/CdO nanoparticles-based hybrid nanosensor

In this report, a glassy carbon electrode (GCE) modified with carbon-based core–shell structures (CSC) with CdO nanoparticles has been prepared and performed for the electrochemical detection of Balsalazide (BLZ). The electrochemical investigation of BLZ was carefully examined using cyclic voltammetry (CV) and differential pulse voltammetry (DPV) on the bare GCE, and CSC-CdO/GCE. Compared to bare GCE, the proposed CSC-CdO/GCE sensor can remarkably enhance the electrocatalytic activity towards the oxidation of BLZ with an increase in the anodic peak currents. For the optimum of experimental conditions, the influence of supporting electrolyte, the pH, concentration of the nanosensor, and scan rate on the peak potentials and current were investigated on the current response of BLZ before the electrochemical determination of BLZ in commercial human serum and urine samples for GCE, and CSC-CdO/GCE. The limit of detection (LOD) for BLZ in the linear range of 8.00 × 10−9 – 8.00 × 10−5 mol/L was determined as 2.20 × 10−9 mol/L. Recovery measurements assessed the accuracy of the proposed sensor in serum and urine samples. The developed sensor indicated high sensitivity and great stability toward BLZ. Core-shell structures are frequently preferred in sensor applications due to their perfect shapes, active catalytic sites, rapid interfacial transport of pores at different length scales, and their ability to reduce or shorten diffusion action paths. CSC was used as a modification material in this study due to its superior properties and advantages. Since CSC has a high surface area during the electron transfer process, it enables more efficient charge transfer between the electrode and the electrolyte. In the study, CdO nanoparticle modification on the CSC was ensured for a synergistic effect to enhance the surface area, electroactivity, and selectivity. After morphological, physical, and chemical characterization of composite material, electrochemical experiments showed that it is extremely promising because of its wide linear concentration range, low LOD, and nearly no interference with some interfering compounds and ions.