Modulation of the superficial electronic structure via metal–support interaction for H2 evolution over Pd catalysts

Electronic interactions can radically enhance the performance of supported metal catalysts and are critical for fundamentally understanding the nature of catalysts. However, at the microscopic level, the details of such interactions tuning the electronic properties of the sites on the metal particle''s surface and metal–support interface remain obscure. Herein, we found polarized electronic metal–support interaction (pEMSI) in oxide-supported Pd nanoparticles (NPs) describing the enhanced accumulation of electrons at the surface of NPs (superficial Pd^δ−) with positive Pd atoms distributed on the interface (interfacial Pd^δ+). More superficial Pd^δ− species mean stronger pEMSI resulting from the synergistic effect of moderate Pd–oxide interaction, high structural fluxionality and electron transport activity of Pd NPs. The surface Pd^δ− species are responsible for improved catalytic performance for H₂ evolution from metal hydrides and formates. These extensive insights into the nature of supported-metal NPs may open new avenues for regulating a metal particle''s electronic structure precisely and exploiting high-performance catalysts.

A new type of electronic effect, polarized metal-support interaction (pEMSI), in oxide-supported Pd nanoparticles describing the enhanced accumulation of electrons at the superficial surface is responsible for improved catalytic H₂ evolution.     

Synthesis of open-mouthed,yolk–shell Au@AgPd nanoparticles with access to interior surfaces for enhanced electrocatalysis

We have successfully produced open-mouthed, yolk–shell (OM-YS) Au@AgPd nanoparticles (NPs) via galvanic replacement reaction at room temperature; each NP has a large opening on its AgPd shells. Owing to the openings on the AgPd shells, the inner surfaces of the AgPd shells of as-prepared OM-YS Au@AgPd NPs become accessible to the surrounding media. These new structural characters make the present OM-YS Au@AgPd NPs excellent catalysts for electrochemical oxidation of ethanol in alkaline media. Their electrochemical active surface area is 87.8 m² g^–1 and the mass activity is 1.25 A mg_Pd^–1. Moreover, the openings on the AgPd shells also make the surfaces of the Au cores in OM-YS Au@AgPd NPs accessible to the reaction media, which significantly facilitates the removal of CO and other carbonaceous intermediate species, thus leading to substantially enhanced durability and stability. This superior electrocatalytic performance cannot be implemented by using conventional YS Au@AgPd NPs or commercially available Pd/C catalysts.     

Bimetallic palladium–gold nanoparticles synthesized in ionic liquid microemulsion

The palladium and gold precursors were dissolved in dispersive and continuous phase of ionic liquid microemulsion (H₂O/Triton X-100 (TX-100)/1-butyl-3-methylimidazolium hexafluorophosphate), respectively. [PdCl₆]^2? ions were reduced in situ by TX-100 in dispersive phase (H₂O) to prepare Pd nanoparticles (NPs) and then [AuCl₄]^? crossed through the interface film and reacted with the as-prepared Pd NPs to form Pd₄Au NPs. The as-prepared Pd₄Au NPs were characterized by transmission electronic microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction, and ultraviolet–visible spectroscopy. The as-prepared Pd₄Au NPs suspension and carbon nanotubes (CNTs) suspension were vigorously stirred to prepare the electrocatalyst supported on the CNTs with a total metal loading of 20?wt.% (denoted by Pd₄Au/CNTs). Cyclic voltammetry and chronoamperometry tests show that the Pd₄Au/CNTs are very promising for the oxidation of ethanol in alkaline medium. The result can be attributed to the synergistic effect between Pd and Au during the catalytic process.     

Catalytic dehydrogenation of natural terpenes via CuPd alloy nanoparticles generated on mesoporous graphitic carbon nitride

A facile wet-chemical protocol for the synthesis of bimetallic CuPd alloy nanoparticles (NPs) anchored on mesoporous graphitic carbon nitride (m-gCN), serving as both stabilizer and support material, was presented herein. The presented protocol allowed to synthesize nearly monodisperse CuPd alloy NPs with an average particle size of 3.9 ± 0.9 nm without use of any additional surfactants and to prepare CuPd/m-gCN nanocatalysts with different Cu/Pd compositions (Cu₂₅Pd₇₅/m-gCN, Cu₃₅Pd₆₅/m-gCN, Cu₁₆Pd₇₄/m-gCN, Cu₃₂Pd₆₈/m-gCN, Cu₁₀Pd₉₀/m-gCN, and Cu₅₀Pd₅₀/m-gCN). After the detailed characterization of CuPd/m-gCN nanocatalysts, they were utilized as catalysts in the dehydrogenation of terpenes. Among all tested nanocatalysts, Cu₅₀Pd₅₀/m-gCN showed the highest activity in terms of the product yields within the same reaction time. Various parameters influencing the catalytic activity of Cu₅₀Pd₅₀/m-gCN were studied using himachalene as a model substrate and the optimum conditions were determined. Under the optimized reaction conditions, the catalytic application of Cu₅₀Pd₅₀/m-gCN nanocatalysts was extended to nine different terpenes and the corresponding products were obtained in high conversion yields (>90%) under mild conditions. A reusability test showed that Cu₅₀Pd₅₀/m-gCN nanocatalysts can be re-used up to four cycles without significant loss in their initial activity.     

Hydrogen evolution-assisted one-pot aqueous synthesis of hierarchical trimetallic PdNiRu nanochains for hydrazine oxidation reaction

A hydrogen evolution-assisted one-pot aqueous approach was developed for facile synthesis of trimetallic Pd Ni Ru alloy nanochain-like networks(Pd Ni Ru NCNs) by only using KBH_4 as the reductant, without any specific additive(e.g. surfactant, polymer, template or seed). The products were mainly investigated by transmission electron microscopy(TEM), X-ray diffraction(XRD) and X-ray photoelectron spectroscopy(XPS). The hierarchical architectures were formed by the oriented assembly growth and the diffusioncontrolled deposition in the presence of many in-situ generated hydrogen bubbles. The architectures had the largest electrochemically active surface area(ECSA) of 84.32 m~2 g~(–1) Pdthan Pd Ni nanoparticles(NPs,65.23 m~2 g~(–1) Pd), Pd Ru NPs(23.12 m~2 g~(–1) Pd), Ni Ru NPs(nearly zero), and commercial Pd black(6.01 m~2 g~(–1) Pd), outperforming the referenced catalysts regarding the catalytic characters for hydrazine oxygen reaction(HOR). The synthetic route provides new insight into the preparation of other trimetallic nanocatalysts in fuel cells.     

Topological prediction of palladium coordination cages

The preparation of functionalized, heteroleptic Pd_xL_2x coordination cages is desirable for catalytic and optoelectronic applications. Current rational design of these cages uses the angle between metal-binding (∠B) sites of the di(pyridyl)arene linker to predict the topology of homoleptic cages obtained via non-covalent chemistry. However, this model neglects the contributions of steric bulk between the pyridyl residues—a prerequisite for endohedrally functionalized cages, and fails to rationalize heteroleptic cages. We describe a classical mechanics (CM) approach to predict the topological outcomes of Pd_xL_2x coordination cage formation with arbitrary linker combinations, accounting for the electronic effects of coordination and steric effects of linker structure. Initial validation of our CM method with reported homoleptic Pd₁₂LFu₂₄ (LFu = 2,5-bis(pyridyl)furan) assembly suggested the formation of a minor topology Pd₁₅LFu₃₀, identified experimentally by mass spectrometry. Application to heteroleptic cage systems employing mixtures of LFu (∠B = 127°) and its thiophene congener LTh (∠B = 149° ∠B_exp = 152.4°) enabled prediction of Pd₁₂L₂₄ and Pd₂₄L₄₈ coordination cages formation, reliably emulating experimental data. Finally, the topological outcome for exohedrally (LEx) and endohedrally (LEn) functionalized heteroleptic Pd_xL_2x coordination cages were predicted to assess the effect of steric bulk on both topological outcomes and coordination cage yields, with comparisons drawn to experimental data.

A molecular mechanics approach enables the accurate prediction of polyhedral topology for homoleptic and heteroleptic palladium M_xL_2x coordination cages, allowing for new insight and design when considering endo- and exo-hedral functionalization.     

Solar-microbial hybrid device based on oxygen-deficient niobium pentoxide anodes for sustainable hydrogen production

Hydrogen gas is emerging as an attractive fuel with high energy density for the direction of energy resources in the future. Designing integrated devices based on a photoelectrochemical (PEC) cell and a microbial fuel cell (MFC) represents a promising strategy to produce hydrogen fuel at a low price. In this work, we demonstrate a new solar-microbial (PEC–MFC) hybrid device based on the oxygen-deficient Nb₂O₅ nanoporous (Nb₂O_5–x NPs) anodes for sustainable hydrogen generation without external bias for the first time. Owing to the improved conductivity and porous structure, the as-prepared Nb₂O_5–x NPs film yields a remarkable photocurrent density of 0.9 mA cm^–2 at 0.6 V (vs. SCE) in 1 M KOH aqueous solution under light irradiation, and can achieve a maximum power density of 1196 mW m^–2 when used as an anode in a MFC device. More importantly, a solar-microbial hybrid system by combining a PEC cell with a MFC is designed, in which the Nb₂O_5–x NPs electrodes function as both anodes. The as-fabricated PEC–MFC hybrid device can simultaneously realize electricity and hydrogen using organic matter and solar light at zero external bias. This novel design and attempt might provide guidance for other materials to convert and store energy.     

Transition‐metal compatibilization of poly(4‐bromostyrene) and polybutadiene via palladium(0) catalyzed reactions

Immiscible blends of 1,2‐polybutadiene and poly(4‐bromostyrene) can be compatibilized by rather low concentrations of Pd⁽⁰⁾[P(C₆H₅)₃]₄ at ambient temperature and 60 °C under argon. Two distinct glass‐transition temperatures merge into a single glass‐transition temperature at high enough concentrations of Pd⁽⁰⁾ (i.e., 2 or 3 mol %). Compatibilization does not occur if Pd⁽⁰⁾ is absent, triphenylphosphine is added without Pd⁽⁰⁾, or polystyrene is not functionalized. The methodology described herein is also useful for inducing melting‐point depression of 2,7‐dibromofluorene in ternary complexes with 1,2‐polybutadiene and Pd⁽⁰⁾. A 72/28 complex of poly(4‐bromostyrene) and 1,2‐polybutadiene with 5.5 mol % Pd⁽⁰⁾ exhibits a reinforced rubbery response with a modulus of 1.2 × 10⁷ N/m², a fracture strain of 235%, and a single glass‐transition temperature. Mechanical properties of these compatibilized ternary systems compare well with those of styrene–butadiene block copolymers, particularly above 100% strain. A five‐step mechanism that includes oxidative addition, olefin coordination, migratory insertion, β‐hydride elimination, and reductive elimination in the coordination sphere of the transition metal is proposed to illustrate how either poly(4‐bromostyrene) or 2,7‐dibromofluorene is linked covalently to alkene side groups in the diene polymer via the Heck reaction. © 2001 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 39: 677–688, 2001     

A new algorithm for inactive orbital optimization in valence bond theory

This paper presents an efficient algorithm for energy gradients in valence bond self-consistent field (VBSCF) method with non-orthogonal orbitals. The frozen core approximation method is extended to the case of non-orthogonal orbitals. The expressions for the total energy and its gradients are presented by introducing auxiliary orbitals, where inactive orbitals are orthogonal, while active orbitals are non-orthogonal themselves but orthogonal to inactive orbitals. It is shown that our new algorithm has a low scaling of (N _a + 1)m ⁴, where N _a and m are the numbers of the active orbitals and basis functions, respectively, and is more efficient than the existing VBSCF algorithms.     

Transfer Hydrogenation(TH) of Carbonyl Compounds Catalytically Promoted by Pd17Se15 Nanoparticles and PdP2 Nanoflowers

Nanosized Pd₁₇Se₁₅ and PdP₂ were synthesized at moderate temperature (using less toxic TOPO in case of PdP₂) and explored for the first time to catalyze transfer hydrogenation (TH) of aldehydes / ketones using 2-propanol as a source of hydrogen. The optimum catalyst loading was equivalent to 1.0 mol % of Pd. The round shaped Pd₁₇Se₁₅ NPs (15 to 30 nm), resulted on reacting (3-(phenylseleno)propylamine) with Na₂PdCl₄ in a mixture (1 : 1) of olylamine and 1-octadecene at 250 °C for 50 min. Nanoflowers of PdP₂ (25 to 55 nm) were obtained by reacting Na₂PdCl₄ with trioctylphosphine oxide (TOPO) in a similar solvent mixture at 350 °C for 60 min. Both the NPs were found air insensitive and authenticated with powder X-ray diffraction, HR-TEM, SEM, SEM-EDX and XPS. The conversion was found more efficient for aldehydes in comparison to that of ketones. In comparison to most of the other Pd based nano-phases, reported earlier, the present NPs are somewhat better activators for TH.     

The Application of HEXS and HERFD XANES for Accurate Structural Characterisation of Actinide Nanomaterials: The Case of ThO2

The structural characterisation of actinide nanoparticles (NPs) is of primary importance and hard to achieve, especially for non-homogeneous samples with NPs less than 3 nm. By combining high-energy X-ray scattering (HEXS) and high-energy-resolution fluorescence-detected X-ray absorption near-edge structure (HERFD XANES) analysis, we have characterised for the first time both the short- and medium-range order of ThO₂ NPs obtained by chemical precipitation. By using this methodology, a novel insight into the structures of NPs at different stages of their formation has been achieved. The pair distribution function revealed a high concentration of ThO₂ small units similar to thorium hexamer clusters mixed with 1 nm ThO₂ NPs in the initial steps of formation. Drying the precipitates at around 150 °C promoted the recrystallisation of the smallest units into more thermodynamically stable ThO₂ NPs. HERFD XANES analysis at the thorium M₄ edge, a direct probe for f states, showed variations that we have correlated with the breakdown of the local symmetry around the thorium atoms, which most likely concerns surface atoms. Together, HEXS and HERFD XANES are a powerful methodology for investigating actinide NPs and their formation mechanism.     

Structural models and atomic distribution of bimetallic nanoparticles as investigated by X-ray absorption spectroscopy

In this report, we describe a general methodology to determine the extent of alloying or atomic distribution quantitatively in bimetallic nanoparticles (NPs) by X-ray absorption spectroscopy (XAS). The structural parameters determined in these studies serve as a quantitative index and provide a general route to determine the structural aspects of the bimetallic NPs. We have derived various types of possible structural models based on the extent of alloying and coordination number parameters of bimetallic NPs. We also discussed the nature of homo- and heterometallic interactions in bimetallic NPs based on the extent of alloying. Herein, we use carbon-supported platinum-ruthenium bimetallic nanoparticles to demonstrate the proposed methodology, and this can be extended further to get more insights into the alloying extent or atomic distribution of other bimetallic systems. The results demonstrated in this paper open up methods to determine the atomic distribution of bimetallic NPs, which is an extremely important parameter that strongly influences the physicochemical properties of NPs and their applications.     

Carbon–hydrogen (C–H) bond activation at PdIV: a Frontier in C–H functionalization catalysis

The direct functionalization of carbon–hydrogen (C–H) bonds has emerged as a versatile strategy for the synthesis and derivatization of organic molecules. Among the methods for C–H bond activation, catalytic processes that utilize a Pd^II/Pd^IV redox cycle are increasingly common. The C–H activation step in most of these catalytic cycles is thought to occur at a Pd^II centre. However, a number of recent reports have suggested the feasibility of C–H cleavage occurring at Pd^IV complexes. Importantly, these latter processes often result in complementary reactivity and selectivity relative to analogous transformations at Pd^II. This mini review highlights proposed examples of C–H activation at Pd^IV centres. Applications of this transformation in catalysis as well as mechanistic details obtained from stoichiometric model studies are discussed. Furthermore, challenges and future perspectives for the field are reviewed.     

Remediation of azo-dyes based toxicity by agro-waste cotton boll peels mediated palladium nanoparticles

The present study reports an environmental benign route for the synthesis of palladium nanoparticles (Pd NPs) using agro-waste empty cotton boll peels aqueous extract for the first time. Surface Plasmon Resonance (SPR) band in absorption spectrum of Pd NPs at 275 nm confirmed the formation of Pd NPs by using UV–Vis spectroscopy. Crystalline nature of Pd NPs was confirmed by powder XRD analysis. Size and morphology was studied by transmission electron microscopy (TEM). The cotton peels extract acted as a source of phytochemicals which primarily reduced Pd⁺² to Pd⁰ nanoparticles (Pd NPs) and imparted stability of Pd NPs by surface capping. The characteristic functional groups of phytochemicals in extract and capped Pd NPs surfaces were identified by FT-IR analysis. Catalytic activity of the synthesised Pd NPs was checked against reduction of hazardous azo-dyes such as Congo red, Methyl orange, Sunset yellow and Tartrazine with NaBH₄ as electron donors. Pd NPs catalysed reduction of all azo-dyes by NaBH₄ in aqueous medium was monitored by UV–visible spectroscopy where Pd NPs mediated transfer of electrons from NaBH₄ to azo-dyes as carrier. The synthesized Pd NPs acted as a good catalyst and could be a promising material in degrading toxic azo-dyes from industrial effluents and wastewater.     

Thiophene and Selenophene Binding at a Pd3 Cluster Site

We report the triply bridging coordination of thiophene and selenophene to a trinuclear metal cluster site. The triply bridging coordination of selenophene at a Pd₃ site forms a unique spiro-type Pd₅ cluster. Furthermore, either thiophene or selenophene is accommodated stably at a Pd₃ site supported by a backside μ₃-cyclooctatetraene ligand through the face-capping μ₃-coordination. The Pd₃ site supported by the cyclooctatetraene ligand showed higher binding affinity of benzene over thiophene, although a Pd₂ site strongly favors thiophene over benzene.     

Biodegradable Nanoparticles Loaded with Levodopa and Curcumin for Treatment of Parkinson’s Disease

Background: Parkinson’s disease (PD) is the second most common age-related neurodegenerative disorder. Levodopa (L-DOPA) remains the gold-standard drug available for treating PD. Curcumin has many pharmacological activities, including antioxidant, anti-inflammatory, antimicrobial, anti-amyloid, and antitumor properties. Copolymers composed of Poly (ethylene oxide) (PEO) and biodegradable polyesters such as Poly (ε-caprolactone) (PCL) can self-assemble into nanoparticles (NPs). This study describes the development of NH₂–PEO–PCL diblock copolymer positively charged and modified by adding glutathione (GSH) on the outer surface, resulting in a synergistic delivery of L-DOPA curcumin that would be able to pass the blood–brain barrier. Methods: The NH₂–PEO–PCL NPs suspensions were prepared by using a nanoprecipitation and solvent displacement method and coated with GSH. NPs were submitted to characterization assays. In order to ensure the bioavailability, Vero and PC12 cells were treated with various concentrations of the loaded and unloaded NPs to observe cytotoxicity. Results: NPs have successfully loaded L-DOPA and curcumin and were stable after freeze-drying, indicating advancing into in vitro toxicity testing. Vero and PC12 cells that were treated up to 72 h with various concentrations of L-DOPA and curcumin-loaded NP maintained high viability percentage, indicating that the NPs are biocompatible. Conclusions: NPs consisting of NH₂–PEO–PCL were characterized as potential formulations for brain delivery of L-DOPA and curcumin. The results also indicate that the developed biodegradable nanomicelles that were blood compatible presented low cytotoxicity.     

Assembly immobilized palladium(0) on carboxymethylcellulose/Fe3O4 hybrid: An efficient tailor‐made magnetically catalyst for the Suzuki–Miyaura couplings

The Pd nanoparticles (Pd NPs) embedded on magnetically retrievable carboxymethylcellulose/Fe₃O₄ (Pd⁰@CMC/Fe₃O₄) organic/inorganic hybrid were prepared via the conventional simple process. The presence of the hydroxyl and carboxyl groups within the framework of the magnetic hybrid enables the facile preparation and stabilization of Pd NPs in this organic/inorganic hybrid. This hybrid catalyst was very effective in the Suzuki – Miyaura reaction of a variety of aryl halides with arylboronic acid to afford excellent product yields. The catalyst showed good stability and could be easily recovered with an external magnetic field and reused for several times without a significant loss in its catalytic activity. Furthermore, the Pd⁰@CMC/Fe₃O₄ hybrid catalyst was fully characterized by UV–Vis, FT–IR, XRD, SEM, EDX, TEM, XPS and TGA techniques. The hot filtration test suggests that a homogeneous mechanism is operative in Suzuki – Miyaura reaction.     

γ-Al2O3 supported Pd@CeO2 core@shell nanospheres: salting-out assisted growth and self-assembly,and their catalytic performance in CO oxidation

In this paper, we have successfully demonstrated the clean synthesis of high-quality Pd@CeO₂ core@shell nanospheres with tunable Pd core sizes in water, and furthermore loaded the as-obtained Pd@CeO₂ products on commercial γ-Al₂O₃via electrostatic interaction. KBr here plays two key roles in inducing the growth and self-assembly of Pd@CeO₂ core@shell nanospheres. First, Br^– ions can retard the reduction of Pd²⁺ ions via the formation of the more stable complex of [PdBr₄]^2– so as to tune the size of Pd cores. Second, it greatly decreases the colloidal stability, and hence the surface polarity-weakened Pd and CeO₂ NPs have to spontaneously self-assemble into more stable and ordered structures. Among different-sized Pd samples, the as-obtained 8 nm-Pd@CeO₂/Al₂O₃ one exhibits the best performance in catalytic CO oxidation, which can catalyze 100% CO conversion into CO₂ at 95 °C, which is much lower than the previously reported CeO₂-encapsulated Pd samples.     

Biogenic Synthesis of CuO,ZnO, and CuO–ZnO Nanoparticles Using Leaf Extracts of Dovyalis caffra and Their Biological Properties

Biogenic metal oxide nanoparticles (NPs) have emerged as a useful tool in biology due to their biocompatibility properties with most biological systems. In this study, we report the synthesis of copper oxide (CuO), zinc oxide (ZnO) nanoparticles (NPs), and their nanocomposite (CuO–ZnO) prepared using the phytochemical extracts from the leaves of Dovyalis caffra (kei apple). The physicochemical properties of these nanomaterials were established using some characterization techniques including X-ray diffraction analysis (XRD), ultraviolet-visible spectroscopy (UV-vis), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy-dispersive X-ray spectroscopy (EDX). The XRD result confirmed the presence of a monoclinic CuO (Tenorite), and a hexagonal ZnO (Zincite) nanoparticles phase, which were both confirmed in the CuO–ZnO composite. The electron microscopy of the CuO–ZnO, CuO, and ZnO NPs showed a mixture of nano-scale sizes and spherical/short-rod morphologies, with some agglomeration. In the constituent’s analysis (EDX), no unwanted peak was found, which showed the absence of impurities. Antioxidant properties of the nanoparticles was studied, which confirmed that CuO–ZnO nanocomposite exhibited better scavenging potential than the individual metal oxide nanoparticles (CuO, and ZnO), and ascorbic acid with respect to their minimum inhibitory concentration (IC₅₀) values. Similarly, the in vitro anticancer studies using MCF7 breast cancer cell lines indicated a concentration-dependent profile with the CuO–ZnO nanocomposite having the best activity over the respective metal oxides, but slightly lower than the standard 5-Fluorouracil drug.     

Salt Stress Mitigation via the Foliar Application of Chitosan-Functionalized Selenium and Anatase Titanium Dioxide Nanoparticles in Stevia (Stevia rebaudiana Bertoni)

High salt levels are one of the significant and major limiting factors on crop yield and productivity. Out of the available attempts made against high salt levels, engineered nanoparticles (NPs) have been widely employed and considered as effective strategies in this regard. Of these NPs, titanium dioxide nanoparticles (TiO₂ NPs) and selenium functionalized using chitosan nanoparticles (Cs–Se NPs) were applied for a quite number of plants, but their potential roles for alleviating the adverse effects of salinity on stevia remains unclear. Stevia (Stevia rebaudiana Bertoni) is one of the reputed medicinal plants due to their diterpenoid steviol glycosides (stevioside and rebaudioside A). For this reason, the current study was designed to investigate the potential of TiO₂ NPs (0, 100 and 200 mg L⁻¹) and Cs–Se NPs (0, 10 and 20 mg L⁻¹) to alleviate salt stress (0, 50 and 100 mM NaCl) in stevia. The findings of the study revealed that salinity decreased the growth and photosynthetic traits but resulted in substantial cell damage through increasing H₂O₂ and MDA content, as well as electrolyte leakage (EL). However, the application of TiO₂ NPs (100 mg L⁻¹) and Cs–Se NPs (20 mg L⁻¹) increased the growth, photosynthetic performance and activity of antioxidant enzymes, and decreased the contents of H₂O₂, MDA and EL under the saline conditions. In addition to the enhanced growth and physiological performance of the plant, the essential oil content was also increased with the treatments of TiO₂ (100 mg L⁻¹) and Cs–Se NPs (20 mg L⁻¹). In addition, the tested NPs treatments increased the concentration of stevioside (in the non-saline condition and under salinity stress) and rebaudioside A (under the salinity conditions) in stevia plants. Overall, the current findings suggest that especially 100 mg L⁻¹ TiO₂ NPs and 20 mg L⁻¹ Cs–Se could be considered as promising agents in combating high levels of salinity in the case of stevia.