02274nas a2200253 4500008004100000022001400041245016000055210006900215260000800284300001600292490000700308520136500315653002001680653002201700653002701722653001901749653002601768100001601794700001901810700002101829700001801850700002201868856013001890 2020 eng d a1944-824400aNanocrystalline Ag3PO4 for sunlight- and ambient air-driven oxidation of amines: high photocatalytic efficiency and a facile catalyst regeneration strategy0 aNanocrystalline Ag3PO4 for sunlight and ambient airdriven oxidat cJUL a29324-293340 v123 a

Selective oxidation of amines to imines using sunlight as clean and renewable energy source is an important but challenging chemical transformation because of high reactivity of the generated imines and lack of visible light-responsive materials with high conversion rates. In addition, oxygen gas has to be purged in the reaction mixture in order to increase the reaction efficiency which, in itself, is an energy-consuming process. Herein, we report, for the first time, the use of Ag3PO4 as an excellent photocatalyst for the oxidative coupling of benzyl amines induced by ambient air in the absence of any external source of molecular oxygen at room temperature. The conversion efficiency for the selective oxidation of benzyl amine was found to be greater than 95% with a selectivity of >99% after 40 min of light irradiation indicating an exceptionally high conversion efficiency with a rate constant of 0.002 min(-1), a turnover frequency of 57 h(-1), and a quantum yield of 19%, considering all of the absorbed photons. Ag3PO4, however, is known for its poor photostability owing to a positive conduction band position and a favorable reduction potential to metallic silver. Therefore, we further employed a simple catalyst regeneration strategy and showed that the catalyst can be recycled with negligible loss of activity and selectivity.

10aamine oxidation10aenergy harvesting10ananocrystalline Ag3PO410aPhotocatalysis10aregeneration strategy1 aGarg, Reeya1 aMondal, Sanjit1 aSahoo, Lipipuspa1 aVinod, C., P.1 aGautam, Ujjal, K. uhttp://library.ncl.res.in/content/nanocrystalline-ag3po4-sunlight-and-ambient-air-driven-oxidation-amines-high-photocatalytic02319nas a2200229 4500008004100000022001400041245016200055210006900217260000900286300001600295490000600311520149100317100001901808700002101827700002101848700001901869700002101888700001801909700001901927700002201946856012101968 2020 eng d a2050-748800aWavelength dependent luminescence decay kinetics in `quantum-confined' g-C(3)N(4)nanosheets exhibiting high photocatalytic efficiency upon plasmonic coupling0 aWavelength dependent luminescence decay kinetics in quantumconfi cOCT  a20581-205920 v83 a

Serendipitous observations offer newer insights into materials properties. Here we describe g-C(3)N(4)nanosheets exhibiting remarkably blue-shifted photoluminescence within the 390-580 nm range centred at 425 nm which matches more closely with its `quantum-dots', and yet is excitation-wavelength independent. Moreover, surprisingly, the luminescence decay becomes increasingly slow at higher emission wavelengths, by up to 10 times. The nanosheets absorb only a fraction of visible-light. To improve this, when we designed a nanocomposite of g-C(3)N(4)and Au nanoparticles (NPs), it retained the PL characteristics and also exhibited excellent light-harvesting and photocatalytic efficiency for benzylamine (BA) oxidation. The surface plasmon resonance of the Au NPs is responsible for the high visible-light response and assisting the reaction by the `hot-electron' injection mechanism, while an uncharacteristic, pronounced co-catalytic effect by them further improves the efficiency. The conversion is 98% with >99% selectivity over 1.5 h of natural sunlight and open-air, probably the highest efficiency for BA photo-oxidation reactions. Even though such a dual role by plasmonic NPs has remained unscrutinized, we argue that the charge-transfer processes for the `hot-carrier' injection and co-catalytic events are well-separated in time due to a much slower photon incident frequency on a catalyst particle, enabling both to occur simultaneously in the same particle.

1 aMondal, Sanjit1 aSahoo, Lipipuspa1 aVaishnav, Yuvraj1 aMishra, Samita1 aRoy, Raj, Sekhar1 aVinod, C., P.1 aDe, Arijit, K.1 aGautam, Ujjal, K. uhttp://library.ncl.res.in/content/wavelength-dependent-luminescence-decay-kinetics-quantum-confined-g-c3n4nanosheets05419nas a2200217 4500008004100000022001400041245011600055210006900171260000800240300001000248490000800258520464600266653001604912653002204928653002904950653003604979100001905015700001805034700002205052856012705074 2021 eng d a0008-622300aAutophagy and unique aerial oxygen harvesting properties exhibited by highly photocatalytic carbon quantum dots0 aAutophagy and unique aerial oxygen harvesting properties exhibit cAUG a16-270 v1813 a

Plastic pollution is a serious threat to the environment as they are not bio-degradable. Herein using waste-polyethylene, we report two inter-related important findings. First that they can be converted economically and completely into highly photocatalytic carbon quantum-dots (CQDs) using H2O2 as a residue-free oxidant in an acid medium, and they have the ability to enrich a reaction medium with an extraordinary amount of molecular oxygen harvested from the air so that no separate oxygen source is needed while carrying out facile photocatalytic oxidation reactions. Second, when they are not performing any photocatalytic reaction, they exhibit self-sensitized photo-oxidation to convert themselves completely to CO2 in the presence of sunlight, a phenomenon that we term as ‘CQD-autophagy’ by drawing parallels to the death of useless-cells in the body. Such extinction from the reaction media is unique as no other material is known to do so and advantageous because the removal of carbon-dots from a solution is rather inefficient from an industry-viewpoint due to their high solubility. Instead, the inexpensive CQDs can be discarded casually with the notion that they will gradually get eliminated from the environment.

10aCarbon dots10aOxygen-enrichment10aPhotocatalytic oxidation10aSelf-sensitized photo-oxidation1 aMondal, Sanjit1 aVinod, C., P.1 aGautam, Ujjal, K. uhttp://library.ncl.res.in/content/autophagy-and-unique-aerial-oxygen-harvesting-properties-exhibited-highly-photocatalytic02493nas a2200241 4500008004100000022001400041245012400055210006900179260000900248300001100257490000800268520163700276653002601913653002701939653002701966653001901993653002802012100001902040700002102059700001802080700002202098856013102120 2021 eng d a0926-337300aFacile transfer of excited electrons in Au/SnS2 nanosheets for efficient solar-driven selective organic transformations0 aFacile transfer of excited electrons in AuSnS2 nanosheets for ef cJUN  a1199270 v2863 a

Solar driven aerial oxidation processes have gained importance in organic transformations leading to the development of many nanocrystalline photocatalysts. Although such nanomaterials have many potential advantages, they often underperform due to poor visible light absorption and rapid recombination of excitons. Incorporation of plasmonic nanoparticles (NPs) on the catalyst surfaces can extend their response to visible light and improve photocatalytic efficiency by the `hot-electron' injection mechanism. Nanostructures of SnS2 too absorb a part of the visible light to induce many photocatalytic reactions, though their ability to perform the selective and controlled organic transformations has not yet been observed. Herein, we demonstrate the first example of such transformation with the oxidative coupling of various benzylamine (BA) derivatives to imines under ambient conditions using SnS2 nanosheets (NSs). The reaction rate improves manifold and shows similar to 98 % conversion (>99 % selectivity) in 2 h under direct sunlight and open-air when the NSs were decorated with 1.5 wt% Au NPs on (Au/SnS2), making it one of the best catalysts for this reaction. We found that the large enhancement in activity upon Au loading is accompanied by a noticeable change in photo-induced charge accumulation behaviour in Au/SnS2 from the usual ``spike and overshoot'' one and contributed by facile transfer of excited electrons across the Au-SnS2 heterojunction in which Au NPs act as both sources and sinks for the photo-excited electrons. Finally, a detailed mechanism of the oxidation reaction has been proposed.

10aBenzylamine oxidation10aHot-electron injection10aPlasmonic nanoparticle10aSnS2 nanosheet10aSolar energy harvesting1 aMondal, Sanjit1 aSahoo, Lipipuspa1 aVinod, C., P.1 aGautam, Ujjal, K. uhttp://library.ncl.res.in/content/facile-transfer-excited-electrons-ausns2-nanosheets-efficient-solar-driven-selective-organic02344nas a2200193 4500008004100000022001400041245013000055210006900185260000800254300001400262490000700276520164000283100001901923700002401942700001901966700001801985700002202003856012502025 2022 eng d a1463-926200a`Self-activating' Bi3TaO7-Bi4TaO8Br photocatalyst and its use in the sustainable production of pro-fluorophoric rhodamine-1100 aSelfactivating Bi3TaO7Bi4TaO8Br photocatalyst and its use in the cJUL a5514-55230 v243 a

We counter two common notions that (i) photocatalysts are likely to degrade during use with barely any strategy to counter it and (ii) rhodamine-B (RhB) photo-degradation lacks any useful or commercial prospects even after 53 years of its discovery by developing a photocatalyst that continues to improve its activity for similar to 300 h due to a leaching induced `self-activation' process. Rhodamine-110 (Rh110) is a widely used pro-fluorophore in biological studies. However, its commercial production is highly challenging due to the formation of various side-products originating from the presence of the two labile amino side-groups that induce the pro-fluorophore activity, leading to purification difficulties, low yield, and unusually high costs. Herein, we demonstrate a facile strategy to produce pure Rh110 using extremely inexpensive RhB and Bi3TaO7-Bi4TaO8Br heterostructures as a catalyst in sunlight. The catalyst is not just stable over 30 catalytic cycles but also gets activated continuously in successive cycles to produce a reaction yield as high as 88%. The role of the heterostructure, the origin of surface activation, and the RhB -> Rh110 transformation mechanism have been established. Based on 150 days of sunlight experiments, large-scale production prospects (similar to 4000 times scale-up) and isolation of Rh110 have also been realized, paving a novel way for its production by anyone, inexpensive biological essaying, and device fabrication. Continuously improving catalysts are unknown and compensatory leaching of metal atoms from the catalyst surface may pave the way to realize them.

1 aBanoo, Maqsuma1 aChatterjee, Kaustav1 aMondal, Sanjit1 aVinod, C., P.1 aGautam, Ujjal, K. uhttp://library.ncl.res.in/content/self-activating-bi3tao7-bi4tao8br-photocatalyst-and-its-use-sustainable-production-pro02040nas a2200289 4500008004100000022001400041245012200055210006900177260000800246300001100254490000800265520108000273653001801353653002601371653003801397653002001435100002101455700001901476700001901495700001901514700002101533700001601554700001801570700001901588700002201607856012101629 2023 eng d a0926-337300aCovalently interconnected layers in g-C3N4: toward high mechanical stability, catalytic efficiency and sustainability0 aCovalently interconnected layers in gC3N4 toward high mechanical cMAR a1220690 v3223 a

The grim prospects for the industrial utilization of g-C3N4 nanosheets arise from multi-step processing resulting in low material yields and poor visible light response due to quantum confinement. Herein, we introduce a strategy for linking the adjacent layers of g-C3N4 covalently to realize a high surface area without excess mass loss in a one-step process by introducing diethylene glycol as a precursor that produces-(CH2)2-O-(CH2)2-linkers in-situ. Their presence increases interlayer spacing and introduces surface curvatures, discouraging the stacking of a larger number of layers to produce nanosheets with-3 times higher surface area. Interestingly, unlike other layered materials, the linkers also provide extraordinary mechanical stability against exfoliating forces. In addition, the process instills sub-bandgap states and a considerable visible light response at 500 nm to slow down the picosecond exciton recombination dynamics, resulting in-5 times enhancement in H2 generation efficiency from photocatalytic water-splitting over the bulk sample.

10aLayer-linkers10aSustainable synthesis10aTransient absorption spectroscopy10awater-splitting1 aRoy, Raj, Sekhar1 aMondal, Sanjit1 aMishra, Samita1 aBanoo, Maqsuma1 aSahoo, Lipipuspa1 aKumar, Amit1 aVinod, C., P.1 aDe, Arijit, K.1 aGautam, Ujjal, K. uhttp://library.ncl.res.in/content/covalently-interconnected-layers-g-c3n4-toward-high-mechanical-stability-catalytic02075nas a2200253 4500008004100000022001400041245011800055210006900173260000800242490000700250520117600257653003201433653002301465653002101488653003201509653002301541100001901564700002101583700001901604700002101623700003601644700001801680856012301698 2024 eng d a2199-692X00aEnhancing the catalytic activity of Pd nanocrystals towards Suzuki cross-coupling by g-Cg-C3N4 photosensitization0 aEnhancing the catalytic activity of Pd nanocrystals towards Suzu cJAN0 v103 a

Developing renewable means of activating molecules over traditional catalysts for C-C bond formation is desirable for industrial applications. Herein, we report a strategy to improve the efficiency of Pd nanoparticles (NPs) for the Suzuki cross-coupling reactions by visible-light irradiation using g-C3N4 nanosheets (NSs) as photosensitizer. Pd NPs mounted on g-C3N4 become electron-rich under visible-light due to generation of excited electrons in g-C3N4 and thereby accelerate the rate-determining step. Remarkable photocatalytic activity was accomplished utilizing Pd/g-C3N4 for the Suzuki cross-coupling reaction in environmentally benign aqueous settings under room temperature conditions. The activity remarkably improves (similar to 2.5 times) upon light irradiation, yielding one of the highest known turnover frequencies (TOF) of 1858 h(-1) and confirming the photosensitizer role of g-C3N4. The TOF for coupling of aryl bromides is also significantly high (similar to 356 h(-1)). We establish that the low-energy/long-lived excitons preferencially transfer to Pd, paving a way for rational designing photocatalysts for various C-C coupling reactions.

10a2D graphitic carbon nitride10aC-C cross-coupling10aexciton transfer10aheterogeneous photocatalyst10aPhotosensitization1 aMondal, Sanjit1 aSahoo, Lipipuspa1 aBanoo, Maqsuma1 aVaishnav, Yuvraj1 aVinod, Chathakudath, Prabhakara1 aGautam, Ujjal uhttp://library.ncl.res.in/content/enhancing-catalytic-activity-pd-nanocrystals-towards-suzuki-cross-coupling-g-cg-c3n4