01754nas a2200205 4500008004100000022001400041245011500055210006900170260000900239300001600248490000700264520103300271100001901304700001601323700001601339700001501355700002401370700002401394856013001418 2022 eng d a2050-748800aUnderstanding the effect of sodium polyphosphate on improving the chemical stability of Ti3C2Tz MXene in water0 aUnderstanding the effect of sodium polyphosphate on improving th cOCT  a22016-220240 v103 a

Degradation of MXenes in aqueous environments severely limits the application and industrialization of this large family of two-dimensional (2D) materials. Hydrolysis and oxidation are now considered as two main degradation mechanisms and while significant efforts have been directed to prolonging the shelf-life of MXenes, separating and studying their degradation mechanisms have lagged behind. Herein, gas analysis via gas chromatography and Raman spectroscopy were used to investigate the effect of sodium polyphosphate, PP, on the degradation of Ti3C2Tz MXene. Transmission and scanning electron microscopies, as well as X-ray photoelectron spectroscopywere also used as complimentary techniques to support conclusions derived from gas analysis and to confirm the extent of degradation via characterization of solid reaction products. Based on these studies we have determined that the addition of PP to an equal mass of Ti3C2Tz solution can effectively suppress hydrolysis and protect Ti3C2Tz from degradation.

1 aHuang, Shuohan1 aNatu, Varun1 aTao, Jingyi1 aXia, Yumin1 aMochalin, Vadym, N.1 aBarsoum, Michel, W. uhttps://library.ncl.res.in/content/understanding-effect-sodium-polyphosphate-improving-chemical-stability-ti3c2tz-mxene-water02064nas a2200157 4500008004100000022001400041245004600055210004500101260000900146300001600155490000800171520160900179100001601788700002401804856007801828 2023 eng d a1932-744700aMXene surface terminations: a perspective0 aMXene surface terminations a perspective cOCT  a20197-202060 v1273 a

Two-dimensional (2D) transition metal carbides and nitrides are among the newest, and probably largest, families of 2D materials that have been discovered. They have shown promise in many applications, such as electromagnetic shielding, energy storage devices like batteries and supercapacitors, transparent conductive electrodes, as catalysts for hydrogen production, and several others. Their general formula is Mn+1XnTz (n = 1-4) or M1.33XTz, where M is an early transition metal, X is carbon and/or nitrogen, and T-z represents various terminations present upon etching the Al layer. The first MXene discovered, Ti3C2Tz, was synthesized by etching aluminum (Al) from the nanolaminated MAX phase Ti3AlC2 using hydrofluoric acid (HF). Since the discovery of Ti3C2Tz in 2011, more than 30 other MXene chemistries have been reported with different M and X elements. It has been observed that, as expected, changing the MXene chemistry also influences the properties in the range of applications listed above, allowing us to tailor them according to what suits the application of interest the best. Unlike the success in tailoring the M and X elements over the years, attempts to engineer T-z was, until recently, a challenge. A series of recent discoveries and an improved understanding of MXene surface properties has now rendered the customization of T-z possible. This progress added a new ``knob'' that can be turned to further tune MXene properties. The majority of this Perspective is focused on surface terminations: their engineering, characterization, and effect on MXene properties.

1 aNatu, Varun1 aBarsoum, Michel, W. uhttps://library.ncl.res.in/content/mxene-surface-terminations-perspective01772nas a2200193 4500008004100000022001400041245011100055210006900166260000800235300001600243490000700259520108200266100001501348700002701363700001601390700002401406700001701430856013101447 2023 eng d a2050-748800aNon-confined gamma monoclinic sulfur cathode in carbonate electrolyte based room temperature K-S batteries0 aNonconfined gamma monoclinic sulfur cathode in carbonate electro cJUL a15924-159300 v113 a

Potassium-sulfur cells have garnered a lot of interest in grid storage chemistry due to the high abundance of both elements and hence their low cost. However, their development is hindered by the polysulfide shuttle effect and their dependency on electrolytes with limited commercial viability. The inability to use carbonate electrolytes is due to the irreversible reaction between it and PS, rendering the cell useless in the first few cycles. Here we expand our use of monoclinic & gamma;-sulfur in carbon nanofibers (& gamma;S-CNFs) to the potassium-sulfur, K-S, chemistry. Herein we show that using & gamma;-S enables the cells to run for 500 cycles at & SIM;900 mA h g(-1) in commercial carbonate electrolytes. We further attempt to understand the role of & gamma;S-CNFs in K-S cells with electrochemical characterization and postmortem spectroscopy. As far as we are aware this is the first application of & gamma;-S in K-S cells. Its outstanding performance should lead to new avenues for the development of this promising chemistry.

1 aPai, Rahul1 aCardoza, Neal, Amadeus1 aNatu, Varun1 aBarsoum, Michel, W.1 aKalra, Vibha uhttps://library.ncl.res.in/content/non-confined-gamma-monoclinic-sulfur-cathode-carbonate-electrolyte-based-room-temperature-k01879nas a2200241 4500008004100000022001400041245012600055210006900181260000800250300001400258490000600272520104700278100002201325700001601347700001801363700002201381700002001403700002201423700001901445700002401464700002001488856012901508 2023 eng d a2590-239300aPhoto-stable, 1D-nanofilaments TiO2-based lepidocrocite for photocatalytic hydrogen production in water-methanol mixtures0 aPhotostable 1Dnanofilaments TiO2based lepidocrocite for photocat cSEP a2853-28690 v63 a

Water and sunlight are the cleanest, most renewable, and abundant resources on Earth. Developing inexpensive, scalable photocatalysts that are highly stable for hydrogen (H-2) production has long been a cherished dream of humanity. Herein, we report on one-dimensional lepidocrocite-based sub-nanofilaments (NFs), approximate to 5 x 7 & Aring;(2) in cross-section, that generate H-2 from 80:20 v/v water/methanol mixtures when illuminated by simulated sunlight. The NFs were stable in the mixtures for times >4,300 h, 300 h of which were under irradiation. Apparent quantum yields as high as 11.7% were obtained. Based on deuterated water results, we conclude that water is the H-2 source. Further, no carbon dioxide (CO2) due to photocatalytic degradation of methanol was detected. Therefore, the NFs have strong green credentials and lucrative economic prospects for large scale up. We expect these NFs will lead to new lines for developing cheap and ultra-stable materials to produce H-2 photochemically for a long time.

1 aBadr, Hussein, O.1 aNatu, Varun1 aNeatu, Stefan1 aNeatu, Florentina1 aKuncser, Andrei1 aRostas, Arpad, M.1 aRacey, Matthew1 aBarsoum, Michel, W.1 aFlorea, Mihaela uhttps://library.ncl.res.in/content/photo-stable-1d-nanofilaments-tio2-based-lepidocrocite-photocatalytic-hydrogen-production02275nas a2200289 4500008004100000022001400041245007000055210006900125260000800194490000700202520140500209653001801614653001101632653002301643653001301666653002701679100002301706700002301729700002101752700001701773700001601790700001301806700002001819700002401839700002301863856009901886 2023 eng d a0935-964800aUltrafast spectroscopy of plasmons and free carriers in 2D MXenes0 aUltrafast spectroscopy of plasmons and free carriers in 2D MXene cFEB0 v353 a

2D MXenes have diverse and chemically tunable optical properties that arise from an interplay between free carriers, interband transitions, and plasmon resonances. The nature of photoexcitations and their dynamics in three different members of the MXene family, Ti3C2, Mo2Ti2C3, and Nb2C, are investigated using two complementary pump-probe techniques, transient optical absorption, and time-resolved terahertz (THz) spectroscopy. Measurements reveal pronounced plasmonic effects in the visible and near-IR in all three. Optical excitation, with either 400 or 800 nm pulses, results in a rapid increase in lattice temperature, evidenced by a pronounced broadening of the plasmon mode that presents as a plasmon bleach in transient absorption measurements. Observed kinetics of plasmon bleach recovery provide a means to monitor lattice cooling. Remarkably slow cooling, proceeding over hundreds of picoseconds to nanoseconds time scales, implies MXenes have low thermal conductivities. The slowest recovery kinetics are observed in the MXene with the highest free carrier density, viz. Ti3C2, that supports phonon scattering by free carriers as a possible mechanism limiting thermal conductivity. These new insights into photoexcitation dynamics can facilitate their applications in photothermal solar energy conversion, plasmonic devices, and even photothermal therapy and drug delivery.

10a2D properties10aMXenes10aOptical properties10aplasmons10aultrafast spectroscopy1 aColin-Ulloa, Erika1 aFitzgerald, Andrew1 aMontazeri, Kiana1 aMann, Javery1 aNatu, Varun1 aNgo, Ken1 aUzarski, Joshua1 aBarsoum, Michel, W.1 aTitova, Lyubov, V. uhttps://library.ncl.res.in/content/ultrafast-spectroscopy-plasmons-and-free-carriers-2d-mxenes00989nas a2200313 4500008004100000022001400041245010000055210006900155260000800224490000700232653001300239653001800252653002800270653000700298100001900305700001900324700001800343700001800361700002000379700001500399700002300414700002200437700002200459700001800481700001500499700001600514700001700530856012800547 2024 eng d a1616-301X00aSynthesis of Ti1-xWx solid solution MAX phases and derived MXenes for sodium-ion battery anodes0 aSynthesis of Ti1xWx solid solution MAX phases and derived MXenes cOCT0 v3410aBehavior10aCARBIDE MXENE10aINTERCALATION MECHANISM10aTI1 aRatzker, Barak1 aFavelukis, Bar1 aBaranov, Mark1 aRathod, Yugal1 aGreenberg, Avia1 aMesser, Or1 aGoldstein, Dor, A.1 aUpcher, Alexander1 aEzersky, Vladimir1 aMaman, Nitzan1 aBiran, Ido1 aNatu, Varun1 aSokol, Maxim uhttps://library.ncl.res.in/content/synthesis-ti1-xwx-solid-solution-max-phases-and-derived-mxenes-sodium-ion-battery-anodes00772nas a2200145 4500008004100000022001400041245004200055210004200097260000900139490000600148520036500154100001800519700001600537856007300553 2024 eng d a2590-239300aTiO2 spaghetti for sustainable future0 aTiO2 spaghetti for sustainable future cAUG 0 v73 a

TiO2 is widely utilized in applications ranging from paints to solar cells. Recent advancements in synthesizing nano-TiO2 by Badr, Barsoum, et al. have enabled its production at low cost and large scale. These nanostructures, comprising 1D lepidocrocite nanofilaments, show promise in enhancing solar water splitting and several other applications.

1 aRathod, Yugal1 aNatu, Varun uhttps://library.ncl.res.in/content/tio2-spaghetti-sustainable-future02271nas a2200361 4500008004100000022001400041245016600055210006900221260000800290300001100298490000800309520108600317653000801403653002601411653002001437653002701457653003201484653002301516100001801539700001601557700001601573700001901589700002201608700002301630700001801653700001901671700001601690700001901706700001601725700001901741700002101760856012801781 2025 eng d a0360-319900aOptimisation of metallic bismuth nanoparticle supported Pt-Bi(x%)/C hybrid electrocatalyst for cost effective and efficient hydrogen production in alkaline media0 aOptimisation of metallic bismuth nanoparticle supported PtBixC h cAUG a1506990 v1613 a

The present study employed a simple mechanochemical method followed by 24-h ultrasonication to synthesize oxide-free metallic bismuth (Bi) nanoparticles. This was further used to synthesize a Pt-Bi(x%)/C (NC-x) hybrid electrocatalyst for the hydrogen evolution reaction in alkaline media. X-ray photoelectron spectroscopy and contact angle measurements reveal, Bi modifies the electronic structure and surface morphology of the Pt/C electrocatalyst, thus enhancing reaction kinetics and active site availability. The relative three-electrode study reveals that optimised NC-20 electrocatalyst reduces the overpotentials by 10.44 % and enhances the current density by 53 % compared to commercial Pt/C. The practical applicability of the NC-20 electrocatalyst was studied with the 13 cm2 single cell anion exchange membrane electrolyser. The catalyst demonstrates promising performance where the current density of NC-20//IrO2 relatively increases by 22.6 % compared to standard Pt/ C//IrO2, and shows continuous production and stable performance when monitored for 30 h.

10aAEM10aBismuth nanoparticles10aelectrocatalyst10aFull cell electrolysis10ahydrogen evolution reaction10awater electrolysis1 aDokhe, Revati1 aUgale, Atul1 aDube, Onkar1 aVarpe, Vaibhav1 aGalave, Chaitanya1 aHattale, Gangadhar1 aKadam, Rutuja1 aVirole, Vishal1 aKumar, Ajay1 aHusale, Sudhir1 aNatu, Varun1 aShevate, Rahul1 aKanawade, Rajesh uhttps://library.ncl.res.in/content/optimisation-metallic-bismuth-nanoparticle-supported-pt-bixc-hybrid-electrocatalyst-cost04277nas a2200157 4500008004100000245008300041210006900124260000800193490000600201520372100207100002503928700001603953700002003969700002303989856010704012 2025 eng d00aReview on recent progress in synthesis, properties, and applications of MXenes0 aReview on recent progress in synthesis properties and applicatio cDEC0 v53 a

Abstract

MXenes, a noble class of two-dimensional (2D) material, discovered in 2011 have gained attention in recent years. They have attracted significant attention due to their flexible elemental composition, distinctive 2D-layered architecture, large surface area, and abundant surface terminations. Top-down synthesis techniques such as HF etching, alkaline etching, and electrochemical methods are used for MXene synthesis. Alongside these methods, methods like chemical vapor deposition (CVD), template method and plasma enhanced pulsed layer deposition (PELPD) are also used for the thin-film synthesis of MXenes. The discovery of double transition-metal layered MXene, solid, and high entropy MXene open up the prospect of further novel structures. MXenes are electrically conductive and have promising optoelectronic, mechanical, and thermoelectric properties. MXenes have also shown immense potential in biomedicine and environmental applications. The surface chemistry of MXene make them ideal for biosensors, drug delivery, and photothermal therapy, while their photocatalytic and adsorption properties enable efficient removal of pollutants and contaminants from water. This review examines the various MAX phase synthesis methods, such as solid-state reactions, hot isostatic pressing, and spark plasma sintering, followed by top-down techniques like HF etching, alkaline etching, and electrochemical etching, as well as bottom-up methods like CVD, template approaches, and plasma-enhanced pulsed layer deposition. The review also looks into the optical, chemical, and electronic properties of MXene, as well as their advancements in energy storage, optoelectronics, pollution avoidance, biomedical applications, and more.

1 aBorah, Ashish, Jyoti1 aNatu, Varun1 aBiswas, Abhijit1 aSrivastava, Anchal uhttps://library.ncl.res.in/content/review-recent-progress-synthesis-properties-and-applications-mxenes02664nas a2200277 4500008004100000022001400041245017100055210006900226260000800295300001100303490000800314520165600322653002501978653002302003653002902026653002002055653002702075100001002102700003002112700002002142700001602162700003102178700002802209700001902237856013002256 2026 eng d a0378-775300aEnhanced electrochemical performance of flexible polymer supercapacitors through optimization of organic acid-doping, carbon nanomaterials, and fabrication techniques0 aEnhanced electrochemical performance of flexible polymer superca cFEB a2390420 v6663 a

The proliferation of portable and wearable electronics necessitates flexible, high-performance energy storage devices. Flexible supercapacitors are poised to meet these demands due to their high power density, flexibility, and durability but scalable fabrication remains challenging due to costly and complex manufacturing methods. This study addresses this issue by implementing scalable, cost-effective spray coating and screen printing techniques to fabricate flexible micro-interdigitated supercapacitors (FMIS) based on Polyaniline (PANI) composites with carbon nanomaterials, using organic acids as crosslinking agents synthesized via hydrogel strategy. The formation of PANI emeraldine salt was verified through X-ray photoelectron spectroscopy, indicating key amine and imine functionalities, while scanning electron microscopy revealed surface morphologies with enhanced active surface areas beneficial for charge storage. Advanced 3D tomography maps porosity distribution and surface area per unit volume, correlating with electroactive areas calculated from the Randles-Sevcik equation. Electrochemical testing via cyclic voltammetry demonstrates an impressive areal capacitance of 173.2 +/- 9.6 mF cm-2 at 10 mV s-1 with Dunn's method distinguishing capacitive from diffusive contributions. Furthermore, EIS measurements highlight lower solution resistance in screen-printed devices, emphasizing the advantages of optimized electrode morphology for efficient charge transport. This study establishes a scalable approach for high-performance flexible supercapacitors, paving the way for next-generation energy storage solutions.

10aCarbon nanomaterials10aCoating techniques10aFlexible Supercapacitors10aPANI composites10aX-ray micro-tomography1 aParul1 aLakshmi, Racherla, Bhagya1 aUtturkar, Vivek1 aNatu, Varun1 aAramanda, Shanmukha, Kiran1 aRamamurthy, Praveen, C.1 aKaka, Fiyanshu uhttps://library.ncl.res.in/content/enhanced-electrochemical-performance-flexible-polymer-supercapacitors-through-optimization