Quantum enhanced efficiency and spectral performance of paper-based flexible photodetectors functionalized with two dimensional materials.

Flexible photodetectors (PDs) have exotic significance in recent years due to their enchanting potential in future optoelectronics. Moreover, paper-based fabricated PDs with outstanding flexibility unlock new avenues for future wearable electronics. Such PD has captured scientific interest for its efficient photoresponse properties due to the extraordinary assets like significant absorptive efficiency, surface morphology, material composition, affordability, bendability, and biodegradability. Quantum-confined materials harness the unique quantum-enhanced properties and hold immense promise for advancing both fundamental scientific understanding and practical implication. Two-dimensional (2D) materials as quantum materials have been one of the most extensively researched materials owing to their significant light absorption efficiency, increased carrier mobility, and tunable band gaps. In addition, 2D heterostructures can trap charge carriers at their interfaces, leading increase in photocurrent and photoconductivity. This review represents comprehensive discussion on recent developments in such PDs functionalized by 2D materials, highlighting charge transfer mechanism at their interface. This review thoroughly explains the mechanism behind the enhanced performance of quantum materials across a spectrum of figure of merits including external quantum efficiency, detectivity, spectral responsivity, optical gain, response time, and noise equivalent power. The present review studies the intricate mechanisms that reinforce these improvements, shedding light on the intricacies of quantum materials and their significant capabilities. Moreover, a detailed analysis of the technical applicability of paper-based PDs has been discussed with challenges and future trends, providing comprehensive insights into their practical usage in the field of future wearable and portable electronic technologies.

Sign-flipping intrinsic anomalous Hall conductivity with Berry curvature tunability in a half-metallic ferromagnet NbSe2-VSe2 lateral heterostructure.

Single-layer half-metal magnets offer exciting scope in spin electronic quantum applications owing to improved spin transport, reduced interfacial resistance and streamlined device fabrication. Herein, we report the emergence of sign-flipping intrinsic anomalous Hall conductivity (AHC) as a result of changes in Berry curvature under an external electric field and half metallicity in a lateral heterostructure composed of centrosymmetric metallic monolayers 1T-NbSe2 and 1T-VSe2. The metallic monolayers 1T-NbSe2 and 1T-VSe2 laterally interfaced along the zigzag orientation break inversion symmetry at the interface and result in distinctive Berry curvature features. Furthermore, the half-metallic character was prominent with gapped states in the spin-up channel, while the spin-down state remained conductive; we observed the unique manifestation of sign-flipping intrinsic AHC at the Fermi level in addition to the electron- and hole-doped regions. This sign-flipping aspect of AHC at the Fermi level is of fundamental importance from the prospect of real-time device applications as it eliminates the necessity of supplementary actions, such as doping and strain engineering, which are traditionally employed to achieve AHC sign reversal. Additionally, a phase transition from half metal to metal occurs at a field of 0.5 V Å-1 and beyond. Half metallicity with sign switching AHC via external electric field makes the lateral NbSe2-VSe2 heterostructure a potential candidate for real-time energy-efficient low-power spintronic devices.

Large thermoelectric transport in magnetically coupled CrI3/1T-MoS2vdW heterostructure via spin-charge interconversion.

Low-dimensional materials with prominent thermoelectric (TE) effect play a pivotal role in realizing state-of-the-art nanoscale TE devices. The fusion of TE effect with the magnetism through seamless integration of TE and magnetic materials in the 2D limit offers access to control longitudinal as well as transverse TE properties via magnetic proximity effect. Herein, we design a van der Waals (vdW) heterostructure of metallic 1T-MoS2with promising TE properties and a layer-dependent magnetic CrI3material. The result highlights exotic electronic and magnetic configurations of the designed monolayer-CrI3/1T-MoS2vdW heterostructure, which show magnetically-coupled TE characteristics. The observed remarkable magnetic proximity stems from large magnetic anisotropy energy and spin polarization, which are found to be 2.21 meV Cr-1and 12.30%, respectively. To this end, the semiconducting CrI3layer with intrinsic magnetism leads to efficient control and tunability of the observed spin-correlated anomalous Nernst effect. Moreover, a large dimensionless figure of merit of ∼6 and a power factor of∼3.8×1011/τ∘ Wm-1K-2s-1near the Fermi level at 300 K endorse the rejuvenated TE effect. The strong relativistic spin-orbit coupling validates the significant correlation of TE properties with intrinsic magnetic configuration. The present study underscores the significance of the magnetic proximity-governed TE effect in vdW heterostructures to engineer low-dimensional TE devices.

Characterization of coconut milk waste nanocellulose based curcumin-enriched Pickering nanoemulsion and its application in a blended beverage of defatted coconut milk and pineapple juice.

In this study, we aimed to develop a blended beverage enriched with curcumin. The curcumin was incorporated within a Pickering nanoemulsion that was stabilized with nanocellulose. The nanocellulose was synthesized from coconut milk waste residue using 38 %-42 % sulfuric acid (AC) and 5 and 10 min ultrasound (UL) separately and in combination (ACU). While combined treatment showed an increase in particle size with ultrasonication time, PDI was observed to decrease. ACU with 10 min ultrasonication was further used at 0.05 %, 0.1 %, 0.2 %, and 0.3 % for stabilization of curcumin enriched Pickering nanoemulsion. The curcumin in Pickering nanoemulsion fabricated with 0.1 % of nanocellulose with an average particle size and PDI value of 259.6 nm and 0.284, respectively was found to be the most stable as compared to other Pickering nanoemulsions at different pH levels and temperatures. RP-HPLC analysis revealed that with 0.1 % of nanocellulose, the Pickering nanoemulsion was most stable at 2 pH and 63 °C temperatures. The in vitro release of curcumin from Pickering nanoemulsion added to a blended beverage in intestinal phase was 51.58 %, which was higher than the stomach phase (38.19 %). The outcomes clearly showed Pickering nanoemulsion to be a promising carrier for curcumin encapsulation in beverage.

Integrative Modulation of Magnetic Resonance Transverse and Longitudinal Relaxivity in a Cell-Viable Bimagnetic Ensemble, γ-Fe2O3@ZnFe2O4.

The potential application of magnetic nanosystems as magnetic resonance imaging (MRI) contrast agents has been thoroughly investigated. This work seeks to attain robust MRI-contrast efficiency by designing an interacting landscape of a bimagnetic ensemble of zinc ferrite nanorods and maghemite nanoparticles, γ-Fe2O3@ZnFe2O4. Because of competing spin clusters and structural anisotropy triggered by isotropic γ-Fe2O3 and anisotropic ZnFe2O4, γ-Fe2O3@ZnFe2O4 undergoes the evolution of cluster spin-glass state as evident from the critical slowing down law. Such interacting γ-Fe2O3@ZnFe2O4 with spin flipping of 1.2 × 10-8 s and energy barrier of 8.2 × 10-14 erg reflects enhanced MRI-contrast signal. Additionally, γ-Fe2O3@ZnFe2O4 is cell-viable to noncancerous HEK 293 cell-line and shows no pro-tumorigenic activity as observed in MDA-MB-231, an extremely aggressive triple-negative breast cancer cell line. As a result, γ-Fe2O3@ZnFe2O4 is a feasible option for an MRI-contrast agent having longitudinal relaxivity, r1, of 0.46 s-1mM-1 and transverse relaxivity, r2, of 15.94 s-1mM-1, together with r2/r1 of 34.65 at 1.41 T up to a modest metal concentration of 0.1 mM. Hence, this study addresses an interacting isotropic/anisotropic framework with faster water proton decay in MR-relaxivity resulting in phantom signal amplification.

Tunable long-range spin transport in a van der Waals Fe3GeTe2/WSe2/Fe3GeTe2 spin valve.

The seamless integration of two-dimensional (2D) ferromagnetic materials with similar or dissimilar materials can widen the scope of low-power spintronics. In this regard, a vertical van der Waals (vdW) heterostructure of 2D ferromagnets with semiconducting transition metal dichalcogenides (TMDCs) forms magnetic junctions with exceptional stability and electrical control. Interestingly, 2D metallic Fe3GeTe2 (FGT) reveals above room temperature Curie temperatures and has large magneto anisotropy due to spin-orbit coupling. In addition, it also possesses topological states and a large Berry curvature. Herein, we designed the FGT/WSe2/FGT vdW heterostructure with a uniform and sharp interface so that FGT could maintain its inherent electronic properties. Also, the uniform thickness of the barrier provides a smooth flow of spins through the junctions as tunneling exponentially decays with an increasing barrier thickness. However, strong energy-dependent spin polarization is crucial for achieving optimum spin valve properties, such as large tunneling magnetoresistance (TMR) along with the manipulation of the magnitude and sign reversal. We have observed a shifting of high-energy localized minority spin states toward low-energy regions, which causes spin polarization fluctuation between -42.5% and 41% over a wide range of bias voltage. This leads to a negative TMR% of ∼-100% at 0.1 V Å-1 and also a large positive TMR% at 0.2 V Å-1 and -0.4 V Å-1. Besides, the system exhibits a highly tunable large anomalous Hall conductivity (AHC) of 626 S cm-1. Interestingly, such unprecedented electronic behaviour with large and switchable spin polarization, anomalous Hall conductivity and TMR can be incorporated into MTJ devices, which provide electrical control and long-range spin transport. Additionally, the system emerges as a standout candidate in low-power spintronic devices (e.g., MRAM and magnetic sensors) owing to its distinctive energy-dependent electronic structure with a wide range of external bias.

Response to Comment on "Structure-Correlated Magnetic Resonance Transverse Relaxivity Enhancement in Superparamagnetic Ensembles with Complex Anisotropy Landscape".

Y. Gossuin et al. in their Comment on "Structure-Correlated Magnetic Resonance Transverse Relaxivity Enhancement in Superparamagnetic Ensembles with Complex Anisotropy Landscape" [ Langmuir 2023, DOI: 10.1021/acs.langmuir.2c03428] put forward certain concerns about the proposed relaxation dependency hypothesis described in our work [ Langmuir 2022, 38 (36), 11087-11098.]. In this reply to their comment, we would like to express the justification of our considered hypothesis in the complex geometry of nanosystems in order to overcome the raised concerns of MR-relaxivity dependency on such complex landscape of anisotropy.

Quantum magnetic phenomena in engineered heterointerface of low-dimensional van der Waals and non-van der Waals materials.

Investigating magnetic phenomena at the microscopic level has emerged as an indispensable research domain in the field of low-dimensional magnetic materials. Understanding quantum phenomena that mediate the magnetic interactions in dimensionally confined materials is crucial from the perspective of designing cheaper, compact, and energy-efficient next-generation spintronic devices. The infrequent occurrence of intrinsic long-range magnetic order in dimensionally confined materials hinders the advancement of this domain. Hence, introducing and controlling the ferromagnetic character in two-dimensional materials is important for further prospective studies. The interface in a heterostructure significantly contributes to modulating its collective magnetic properties. Quantum phenomena occurring at the interface of engineered heterostructures can enhance or suppress magnetization of the system and introduce magnetic character to a native non-magnetic system. Considering most 2D magnetic materials are used as stacks with other materials in nanoscale devices, the methods to control the magnetism in a heterostructure and understanding the corresponding mechanism are crucial for promising spintronic and other functional applications. This review highlights the effect of electric polarization of the adjacent layer, changed structural configuration at the vicinity of the interface, natural strain induced by lattice mismatch, and exchange interaction in the interfacial region in modulating the magnetism of heterostructures of van der Waals and non-van der Waals materials. Further, prospects of interface-engineered magnetism in spin-dependent device applications are also discussed.

Proximity induced longitudinal and transverse thermoelectric response in graphene-ferromagnetic CrBr3vdW heterostructure.

The integration of longitudinal and transverse thermoelectric (TE) fosters various new opportunities in tuning the charge transport behaviour and opens a platform for efficient thermopower devices. The presence of asymmetric electronic structure supposed to accomplish large thermopower and electronic figure of merit. Herein, we investigate magnetic proximity coupled longitudinal and transverse TE behaviour in heterostructure of monolayer semimetal, graphene and a monolayer ferromagnet, CrBr3under the framework ofab initio-based calculations and employed constant relaxation time approximation (CRTA).The integrated density of states is elevated and asymmetric near Fermi energy region due to seamless proximity integration, depicting mixed character of graphene and CrBr3. The asymmetric nature of electronic structure significantly affects the Seebeck coefficients (S) and electrical conductivity (σ/τ) of heterostructure. The consistent step-like conductance spectrum influences interfacial polarization due to agile proximity integration. The magnitude of Seebeck coefficient (S) is found to be 653µV K-1near Fermi level. The heterostructure observes higher electrical conductivity and power factor in n-type region of the order of 106S m-1and 1020cm-3at room temperature. The dimensionless electronic figure of merit (zTe) advocates the heterostructure system to be an ideal TE material. Alongside longitudinal TE, we also find the heterostructure system is sensitive to anomalous Nernst effect (ANE) (transverse TE) with oscillatory nature. The Seebeck and ANE shows high degree of tunability with applied external electric field. The synergistic existence of Seebeck and ANE due to proximity integration in van der Waals atomic crystal at room temperature will provide realistic approach to experimentally fabricate and develop real-time thermopower devices.

Structure-Correlated Magnetic Resonance Transverse Relaxivity Enhancement in Superparamagnetic Ensembles with Complex Anisotropy Landscape.

The aim of the work is to explore structure-relaxivity relationship by observing transverse relaxivity enhancement in magnetic resonance imaging (MRI) of differently organized superparamagnetic complex ensembles of zinc ferrite isotropic/anisotropic nanosystems. We observe that superparamagnetic systems show a correlation of MRI-transverse relaxivity, r2/r1, with spatial arrangement of nanoparticles, as well as magnetic easy axes and thermal-energy-dependent anisotropy energy landscape. The presence of highly random/partially aligned easy axes with enhanced anisotropy constant leads to modulation in transverse relaxation. As a result, we achieve highest contrast efficiency in compact ensemble of isotropic nanoparticles and hollow core ensemble. Indeed, core-shell ensemble with combined effect of aligned and randomly oriented easy magnetic axes shows a reduction in MRI contrast efficiency. However, we address a hypothesis for transverse contrast efficiency where we depict the correlation among MRI-transverse contrast efficiency with structural complexity of ensembles, differently arranged primary nanoparticles/magnetic easy axes, anisotropy constant, and collective magnetic behavior. In consequence, we simplify the limitation of quantum mechanical outer-sphere diffusion model of magnetic resonance relaxivity by neglecting the contribution of magnetization and introducing an anisotropy constant contribution with complex structure landscape of easy axes.

Nontrivial band topology coupled thermoelectrics in VSe2/MoSe2van der Waals magnetic Weyl semimetal.

The correlation between topological and thermoelectrics promotes numerous interesting electronic phenomena and sets the stage for efficient thermopower devices. Herein, we report nontrivial band topology of 1T-VSe2/1H-MoSe2van der Waals system and also probe its thermoelectric (TE) characteristics on the basis of first-principle calculations. The crossover of bands, which creates a close loop near Fermi level along M-K high symmetry points, gets inverted at former crossing points of bands, under spin-orbit coupling effect. The calculated Chern NumberC= 1 supports the nontrivial band topology whereas the broken time reversal symmetry asserts its magnetic Weyl semimetallic behavior. The nontrivial band topology falls under the category of Type-I Weyl band crossing. We delve into the TE characteristics of the proposed topological material by employing constant relaxation time approximation. The heterostructure shows high electrical conductivity of order 106S m-1at both 300 K and 1200 K, and a low magnitude of Seebeck coefficient (S) value of 79.3µV K-1near room temperature. Such interplay between the topological phase and TE characteristics can lay foundation for next-generation topological-TE devices.

In vitro laboratory analyses of commercial anti-scorpion (Mesobuthus tamulus) antivenoms reveal their quality and safety but the prevalence of a low proportion of venom-specific antibodies.

Mesobuthus tamulus (Indian Red Scorpion) sting is a severe but neglected health issue in India. The accomplishment of in-patient scorpion sting management is highly dependent on the safety, efficacy, and homogeneity of scorpion antivenom preparation. Therefore, in this study, the above qualities of commercial anti-scorpion antivenoms manufactured in India were assessed by in vitro laboratory analyses. Biophysical characterization of venom by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, size exclusion chromatography, and proteomics analysis demonstrated that anti-scorpion antivenoms (ASAs) mostly contain F(ab')2 molecules with a trace amount of undigested immunoglobulin (Ig) G. The physicochemical characterization, electron microscopy, and dynamic light scattering studies revealed that ASAs were prepared according to the guidelines of World Health Organization (WHO), and were devoid of aggregate content and virus particles. ASAs did not show IgE contamination and bacterial endotoxin but demonstrated moderate complement activation properties, which may have adverse effects in treated patients. Spectrofluorometric and atomic force microscopy analyses showed poor binding of venom with commercial ASAs. The percent of antibodies raised against the venom toxins in commercial ASAs was determined at the range of 5.3-6.3%, which is a reason for their poor efficacy. This study advocates the importance of in vitro laboratory analyses for assessing commercial antivenom's quality and safety parameters before their pre-clinical research and clinical use to treat Indian red scorpion sting.

Correction: Enabling methanol oxidation by an interacting hybrid nanosystem of spinel Co3O4 nanoparticle decorated MXenes.

Correction for 'Enabling methanol oxidation by an interacting hybrid nanosystem of spinel Co3O4 nanoparticle decorated MXenes' by Kashmiri Baruah et al., Dalton Trans., 2022, 51, 4324-4337, DOI: 10.1039/D1DT03671H.

Enabling methanol oxidation by an interacting hybrid nanosystem of spinel Co3O4 nanoparticle decorated MXenes.

For the successful implementation of direct methanol fuel cells in commercial applications, highly efficient and durable non-noble electrocatalysts based on conducting and stable non-carbonaceous supports can be potential candidates. Herein, spinel Co3O4 nanoparticles are decorated over Ti3C2 MXene nanosheets for methanol oxidation. The hybrid nanosystem Ti3C2/Co3O4 (TC) reduces restacking of MXene nanosheets, which offers a larger surface area for Co3O4 dispersion, leading to a shorter path for the charge carriers. TC coated on glassy carbon (GC) exhibits a MOR current density of 38.38 A g-1 which is 2.9 times higher than that of Co3O4/GC in 1.5 M methanol at a 20 mV s-1 scan rate. The hydrophilic terminations on the surface of MXenes create strong interactions with the Co3O4 nanoparticles, which increase the MOR kinetics of the nanocomposite. A low onset potential (0.32 V), high oxidation current density of the nanocomposite, efficient durability and cycling stability up to 200 CV cycles make this nanocomposite a better alternative to the state-of-the-art noble-metal electrocatalysts.

Renormalization group analysis of weakly interacting van der Waals Fermi system.

Weak-coupling phenomena of the two-dimensional Hubbard model is gaining momentum as a new interesting research field due to its extraordinarily rich behavior as a function of the carrier density and model parameters. Salmhofer (1998Commun.Math.Phys.194249; 2001Phys.Rev.Lett.87187004) developed a new renormalization-group method for interacting Fermi systems and Metzner (2000Phys.Rev. B617364; 2000Phys.Rev.Lett.855162) implemented this renormalization group analysis of the two-dimensional Hubbard model. In this work, we demonstrate the spin-wave dependent electronic structure and susceptibility behavior of model graphene-phosphorene van der Waals heterostructure in the framework of renormalization group approach. We implement singlet vertex response function for the weakly interacting van der Waals Fermi system with nearest-neighbor hopping amplitudes. This analytical approach is further extended for spin-wave dependent susceptibility behavior. We present the resulting compressibility and phase diagram in the vicinity of half-filling, and also results for the density dependence of the critical energy scale.

Electrochemically active site-rich nanocomposites of two-dimensional materials as anode catalysts for direct oxidation fuel cells: new age beyond graphene.

Direct oxidation fuel cell (DOFC) has been opted as a green alternative to fossil fuels and intermittent energy resources as it is economically viable, possesses good conversion efficiency, as well as exhibits high power density and superfast charging. The anode catalyst is a vital component of DOFC, which improves the oxidation of fuels; however, the development of an efficient anode catalyst is still a challenge. In this regard, 2D materials have attracted attention as DOFC anode catalysts due to their fascinating electrochemical properties such as excellent mechanical properties, large surface area, superior electron transfer, presence of active sites, and tunable electronic states. This timely review encapsulates in detail different types of fuel cells, their mechanisms, and contemporary challenges; focuses on the anode catalyst/support based on new generation 2D materials, namely, 2D transition metal carbide/nitride or carbonitride (MXene), graphitic carbon nitride, transition metal dichalcogenides, and transition metal oxides; as well as their properties and role in DOFC along with the mechanisms involved.

Spin-transfer-torque mediated quantum magnetotransport in MoS2/phosphorene vdW heterostructure based MTJs.

Spin-transfer-torque mediated quantum magnetotransport behaviour can be realized via magnetization density switching in 2D van der Waals heterostructures for device applications. In this context, time-dependent spin-current controls the spin-transfer-torque behaviour within a density functional theory simulation supported by Green's function. Here, magnetotransport characteristics have been revealed in a model semiconducting MoS2/phosphorene van der Waals heterostructure at the nanoscale. We study the dynamics of spin-current channelized heterojunction transport with rotational variation in the magnetization angle. It is observed that the time-varying spin-transfer-torque remains invariant irrespective of the magnetization angle direction. Meanwhile, the polarized spin-current shows a persistent damped oscillatory behavior with the oscillation frequency proportional to the applied external magnetic field. This oscillating behavior shows a transient spin-transfer-torque with close proximity to the steady-state value. These findings support the existence of active interfacial resonant states for spintronic device applications.

Proximity effects in graphene and ferromagnetic CrBr3 van der Waals heterostructures.

Herein, we report first-principles calculations for the magnetic proximity effect in a van der Waals heterostructure formed by a graphene monolayer, induced by its interaction with a two-dimensional (2D) ferromagnet (chromium tribromide, CrBr3). We observed that the magnetic proximity effect arising from the spin-dependent interlayer coupling depends on the interlayer electronic configuration. The proximity effect results in the spin polarization of the graphene orbital by up to 63.6%, together with a miniband splitting of about 73.4 meV, and 8% enhancement in the magnetic moment (3.47 µB per cell) in the heterostructure. The position of the Fermi level in the Dirac cone is shown to depend strongly on the graphene-CrBr3 interlayer separation of 3.77 Å. Consequently, we also show that a perpendicular electric field can be used to control the miniband spin splitting and transmission spectrum. Also, the interfacial polarization effect due to the existence of two different constituents reinforces the conductivity via electrostatic screening in the heterolayer. These findings point towards the application potential of this unique system in nanoscale devices, where the electric field-driven magnetic proximity effect can lead to spin controllability and possible engineering of spin gating.

Graphitic carbon nitride decorated with FeNi3 nanoparticles for flexible planar micro-supercapacitor with ultrahigh energy density and quantum storage capacity.

Portable miniaturized energy storage micro-supercapacitors have attracted significant attention due to their power source and energy storage capacity, replacing batteries in ultra-small electronic devices. Fabrication with porous and 2D graphitic nanomaterials with high conductivity and surface area leads to high-performance micro-supercapacitors. In order to satisfy the fast-growing energy demands for the next generation, we report performance and design of a 2D heterostructured EDLC (g-C3N4) and pseudocapacitor (FeNi3) resulting in short ionic diffusion path and prominent charge storage based on synergic functionalities. This heterostructure system shows an enhanced quantum capacitance (38% enhancement) due to delocalized states near the Fermi level. Having achieved an areal capacitance of 19.21 mF cm-2, capacitive retention (94%), enhanced power density (17-fold), having ultrahigh energy density of 0.30 W h cm-3 and stability of the material even without any obvious degradation after 1000 cycles, this smart heterostructure acts as a new platform for designing high-performance in-plane micro-supercapacitors.

Janus nanoparticles for contrast enhancement of T1-T2 dual mode magnetic resonance imaging.

The accuracy of magnetic resonance imaging (MRI) scanning can be improved using a multifunctional nanosystem having T1-T2 dual contrast enhancement. Specifically, the combination of both T1 and T2 effects in a single system helps in acquiring cross validated information during dual mode MRI and reduces the required dose. In this study, polyethylene glycol (PEG) stabilized MnFe2O4@MnO Janus nanoparticles were developed as novel dual-mode MR imaging agents. MnO contributed to T1 contrast whereas MnFe2O4 enabled T2 contrast. The PEG molecules afforded solubility and stability to the contrast agent in water, making it acceptable for biomedical purposes. The biocompatibility of the developed nanosystem was confirmed by cell viability studies. The r2/r1 ratio remained at a suitable value, justifying the applicability of the contrast agent for dual mode MRI. Finally, the efficiency of the agent for T1-T2 contrast enhancement was confirmed through in vitro and ex vivo MRI experiments.