Spectroscopic Studies Research Articles

Insights into impact of shock wave on structural, optical and surface characteristics of ammonium pentaborate tetrahydrate single crystal

In this study, we are emphasizing on growth of bulk size optically transparent single crystals of ammonium pentaborate tetrahydrate (APB) using the slow evaporation solution technique at room temperature. Initially, crystalline phase of the compound was confirmed through the X-ray diffraction technique. Thereafter, APB has been analysed systematically for its crystallographic structural stability in such a way that its structure has been examined periodically at two shock wave (SW) loaded conditions using XRD measurements. Further, our research contains a comprehensive knowledge about effect of shock wave on rocking curve of APB single crystal measured through high resolution XRD measurement system and the changes in crystalline perfection due to shock wave was analysed. Also, modifications in optical properties were studied due to impact of shock waves. The transmittance was checked through UV-visible spectroscopy and the changes in optical band gap were examined. The defects generated in the APB crystal after every two shocks i.e., shockwave - sample interaction was scrutinized by photoluminescence spectroscopy and surface morphology studies in detail.

Biosynthesis of silver nanoparticle from flower extract of Dillenia indica and its efficacy as antibacterial and antioxidant

Dillenia indica is a medicinal tree of the Dilleniaceae and its flower extract was used for the synthesis of silver nanoparticle (AgNPs). The optimal conditions for AgNPs synthesis were as such: 2 mM AgNO3, pH 4.5 and 48-h reaction time. The characteristic band of AgNPs was observed at the wavelength of 435 nm by UV–visible spectroscopic study. Fourier-transform infrared (FTIR) analysis depicted the involvement of several functional groups of plant extracts in the synthesis of AgNPs. Nanoparticles were mostly spherical shaped and uniformly distributed, when observation was made by Transmission electron microscopy (TEM). Energy Dispersive X-Ray (EDX) showed absorption peak approximately at 3 keV thus confirmed the presence of silver metal in AgNP. X-ray diffraction (XRD) investigation and selected area electron diffraction (SAED) patterns showed the crystalline nature of the AgNPs. Dynamic light scattering (DLS) analysis exhibited average size of the nanoparticles as 50.17 nm with a polydispersity index (PDI) value of 0.298. The zeta potential of nanoparticles was observed as −24.9 mV. To assess antibacterial activity, both AgNPs alone or its combination with the antibiotic were tried against six pathogenic bacteria. The combination of AgNPs with antibiotic was maximum effective against Shigella boydii (16.07 ± 0.35) and Klebsiella pneumoniae (15.03 ± 0.20). AgNPs alone showed maximum inhibition for both Gram-positive bacteria: methicillin-resistant Staphylococcus aureus (19.97 ± 0.20 mm) and Enterococcus faecium (19.80 ± 0.15 mm). Maximum inhibition of Enterobactor cloacae and Pseudomonas aeruginosa was observed by antibiotic taken alone. Evaluation through 2,2-diphenyl-1-picrylhydrazyl (DPPH) and DNA nicking assays demonstrated the antioxidant capabilities of the nanoparticles.

Low Cobalt Single Atoms Loading on N-doped Carbon for High Na Storage Performance

Cobalt single atoms on nitrogen-doped carbon (CoSAs/N-C) were successfully synthesized through the pyrolysis of metal-organic supramolecular self-template. Only 0.12wt% metal-doped CoSAs/N-C anodes bring a rate capacity enhancement of 195 mAh g-1 compared to the blank group of nitrogen-doped carbon electrodes at 0.1Ag-1. In addition, the CoSAs/N-C anodes exhibit remarkable sodium-ion storage capacities of 285 mAh g-1 after 2000 cycles at 1.0Ag-1 and 133 mAh g-1 with an exceptional cycling stability for 10,000 cycles at an ultra-high current density of 20Ag-1, thereby showcasing excellent Na ion storage performance. Ex-situ X-ray photoelectron spectroscopic study demonstrates that some N atoms in CoSAs/N-C can reversibly store and release Na ions during discharge and charge cycles. The full cell assembled with CoSAs/N-C anode and Na3V2(PO4)3 cathode displays Coulombic efficiency of >99.7% after 200 cycles at 0.5Ag-1. Density functional theory (DFT) calculations further reveal that the presence of single-atom Co results in a decrease in the Na adsorption energy surrounding pyrrolic-N and pyridinic-N structures. This moderate adsorption energy may be beneficial for Na ion adsorption and desorption. This study opens up new possibilities of fabricating advanced metal single atom anodes for high-performance sodium-ion batteries.

Accurate reference spectra of HD in an H2–He bath for planetary applications

Context. The hydrogen deuteride (HD) molecule is an important deuterium tracer in astrophysical studies. The atmospheres of gas giants are dominated by molecular hydrogen, and the simultaneous observation of H2 and HD lines provides reliable information on the D/H ratios on these planets. The reference spectroscopic parameters play a crucial role in such studies. Under the thermodynamic conditions encountered in these atmospheres, spectroscopic studies of HD require not only the knowledge of line intensities and positions but also accurate reference data on pressure-induced line shapes and shifts. Aims. Our aim is to provide accurate collision-induced line-shape parameters for HD lines that cover any thermodynamic conditions relevant to the atmospheres of giant planets, namely any relevant temperature, pressure, and perturbing gas composition (the H2–He mixture). Methods. We performed quantum-scattering calculations on our new, highly accurate ab initio potential energy surface (PES), and we used scattering S matrices obtained in this way to determine the collision-induced line-shape parameters. We used cavity ring-down spectroscopy to validate our theoretical methodology. Results. We report accurate collision-induced line-shape parameters for the pure rotational R(0), R(1), and R(2) lines, the most relevant HD lines for investigations of the atmospheres of the giant planets. Besides the basic Voigt-profile collisional parameters (i.e., the broadening and shift parameters), we also report their speed dependences and the complex Dicke parameter, which can influence the effective width and height of the HD lines up to almost a factor of 2 for giant planet conditions. The sub-percent-level accuracy reached in this work is a considerable improvement over previously available data. All the reported parameters (and their temperature dependences) are consistent with the HITRAN database format, hence allowing for the use of the HITRAN Application Programming Interface (HAPI) for generating the beyond-Voigt spectra of HD.

Updated Spectral Characteristics for the Ultracool Dwarf TRAPPIST-1

A comprehensive infrared spectroscopic study of star TRAPPIST-1 is a crucial step toward the detailed examination of its planets. While the presence of Earth’s atmosphere has limited the spectral extent of such a study up to now, the Near Infrared Imager and Slitless Spectrograph (NIRISS) and the Near Infrared Spectrograph instruments aboard the James Webb Space Telescope (JWST) can now yield the 0.6–5 μm spectral energy distribution (SED) of the star. Here we translate TRAPPIST-1's SED into tight constraints on its luminosity (L bol = 0.000566 ± 0.000022 L ⊙), effective temperature (T eff = 2569 ± 28 K), and metallicity ([Fe/H] = 0.052 ± 0.073) and investigate the behavior of its gravity-sensitive indices. Through band-by-band comparisons of the NIRISS and ground-based spectra, TRAPPIST-1 exhibits a blend of both field source and intermediate-gravity spectral characteristics, suggesting that the star is likely a field-age source with spectral features reminiscent of young objects. We also employ photospheric modeling incorporating theoretical and JWST spectra to constrain stellar surface heterogeneities, finding that the limited fidelity of current stellar spectral models precludes definitive constraints on the physical parameters of the distinct spectral components giving rise to TRAPPIST-1's photospheric heterogeneity and variability. In addition, we find intermodel differences in the inferences of properties (e.g., the effective temperature) over one order of magnitude larger than the instrument-driven uncertainties (∼100 K vs. ∼4 K), pointing toward a model-driven accuracy wall. Our findings call for a new generation of stellar models to support the optimal mining of JWST data and further constraining stellar—and ultimately planetary—properties.

Chemical free, bio-Intercalation of selenium nanoparticles for highly accelerated photo-responsive of organic contaminants debasement and their in-vitro anti-bacterial agents, anti-oxidants effect, cyto-toxic analysis

This study investigates the use of Excoecaria agallocha leaves as a bio-template for the intercalation of Selenium nanoparticles (SeNPs). The synthesized SeNPs were characterized using techniques like SEM-EDX, TEM/HR-TEM, and XRD spectroscopic studies. The study found that SeNPs showed maximum cleaning ability at a dosage of 50 μL/mL, with 95% inhibition of DPPH radicals. However, cellular absorption was limited to 55% at concentrations of 300μg/L over a 72-hour period. The synthesized SeNPs also demonstrated a strong cytotoxic effect on MCF-7 breast cancer cell lines, indicating their potential as anti-cancer agents. Further research is needed to fully explore the potential of these novel nanocomposites.

The Effects of Thickness, Polarization, and Strain on Vibrational Modes of 2D Fe3GeTe2

In this study, we investigated the effects of thickness, light polarization, and strain on the Raman spectra of two-dimensional (2D) Fe3GeTe2 (FGT) crystals synthesized via chemical vapor transport. The crystals are thoroughly characterized using a combination of microscopic, diffraction, and spectroscopic techniques. Particularly, a systematic angle-resolved polarized Raman spectroscopy study reveals a clear polarization dependence of the Raman intensity in both parallel and crossed polarization directions, with the Ag1 mode completely disappearing in the crossed polarization direction. The angle-dependent intensity of both the Ag1 and E2g2 modes in parallel polarization and the intensity of the E2g2mode in the crossed polarization remain constant at all angles. These findings align with predictions from Raman tensor analysis, providing compelling evidence for the unambiguous assignment of the Ag1 and E2g2 modes to specific peaks observed in the Raman spectrum of FGT, resolving existing confusion in the literature regarding their assignment. Furthermore, we examine the effect of strain on the Raman spectrum of 2D FGT in-situ using a bending device. Our study, conducted on a monolayer to few-layer 2D FGT deposited onto polyethylene terephthalate and subjected to outward (inward), i.e., tensile (compressive) bending, demonstrates appreciable downshifting (upshifting) of the Raman peak position of both Ag1 and E2g2 modes. These findings are particularly significant given that strain engineering represents an effective approach to modulate the magnetic properties of FGT and other 2D magnetic materials.

Electroadsorption of La3+ and Ce3+ from aqueous media with a carbon paste electrode modified with HMS-CMPO

This work deals with the electroadsorption of rare earths cerium and lanthanum in aqueous solution by using a carbon paste electrode modified with a silica mesoporous material functionalized with carbamoyl methyl phosphine oxide (CMPO). This functionalization was carried out in a two-step synthesis, the intermediate product was synthesized by attaching N-(2-aminoethyl)-3-aminopropyltrimethoxysilane (APTMS) to the surface of the HMS by a grafting method synthesis, then this intermediate was modified by CMPO, in a further condensation reaction. The final product CMPO obtained was characterized by diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), thermal gravimetric analysis (TGA) and N2 adsorption/desorption isotherms using BJH and BET models. Showing thermal stability, a surface area higher than 450m2g-1 and mesoporous properties. The CMPO material was used to modify the mixture of the carbon paste electrode producing an enhancement in the interaction between the electrode surface and the lanthanides studied, at the same time it produces and improvement in the electroactive area by over two orders of magnitude. The modified carbon paste electrode (CMPO-CPE) developed in this work shows an increase in the conductivity, observed with the electrochemical impedance spectroscopy studies, and an increase in the electroactive area of 47% was calculated from cyclic voltammetry experiments. CMPO-CPE was used to extract La3+ and Ce3+ from aqueous solution using NaNO3 as support electrolyte, by using a fixed potential program over time, measuring the obtained current by Chronoamperometric method. The adsorption and desorption results were corroborated with Inductively coupled plasma atomic emission spectroscopy (ICP-OES) demonstrated the capacity of extraction of the electrode were 74μg after ten cycles for La3+ at pH 5.0 and 15μg after ten cycles for Ce3+ at pH 6.0, using a CMPO modified electrode of small surface (3mm radius). This electrode was tested for over 50 cycles without losing their electroactive properties under tested electrochemical conditions.

Design and synthesis of new benzoxazole derivatives and study of their interactions with a G4 model by UV spectroscopy and in silico methods

In this study, we synthesized novel benzoxazol-2-ylmethyl-(1H-1,2,3-triazol-4-yl)phenyl)-3-aminopropanamides (6a-d) in high yields by means of the Copper-catalysed Azide-Alkyne Cycloaddition (CuAAC) reaction. The synthetic pathway involves the conversion of 2-aminophenol to 2-(bromomethyl)benzoxazole 1, followed by its transformation into the azide derivative 2. Subsequent reaction with functionalized arylalkynes 5a-d under Sharpless’s reaction conditions yields the desired compounds 6a-d. These benzoxazoles were then evaluated as G-Quadruplex DNA (G4) ligands by UV spectroscopy studies using a telomeric sequence (Tel22) as G4 model. We studied how the absorbance at λmax varies over time for the 6a-d/Tel22 mixtures at different molar ratios. Moreover we carried out melting experiments in order to point out any possible stabilization effects arising by ligand interaction. Our findings indicate that Tel22 is slighlty but significantly stabilized by compound 6b at a 1:1 ratio. Furthermore for 6b, these results align well with in silico predictions suggesting that the ligand acts as groove binder interacting with six guanosine residues of the telomeric model.

Mechanistic insights and application potentials for CeO2-Al2O3 passive NOx adsorber (PNA) materials

A series of CeO2/Al2O3 with Ce loading from 0.5 to 5.0 wt% were studied as PNA materials for low temperature NOx abatement. Via XRD, TEM imaging and UV–vis spectroscopy studies, it was demonstrated that CeO2 is present as nanoparticles on the Al2O3 support, and the particle size increases with increasing Ce loading. PNA performance of these materials was investigated by NOx trapping followed by TPD. The PNA chemistry was further probed with in situ NO-DRIFT spectroscopy. PNA chemistry involves a rapid direct NO trapping route that leads to surface nitrite formation, and a slower NO2 trapping route that leads to surface nitrate species. Surface nitrite decomposition releases NO at 200–300 °C, suitable for PNA application. Based on NO yields during TPD, the atomic efficiency of surface Ce was calculated, which demonstrates that dispersing CeO2 on high surface area supports is a viable strategy for improving PNA efficiency of CeO2-based materials.

Tuning properties of CTAB-HSA-AuNR nanocomposite antibacterial thin films

Protein-based biomaterials such as thin films have an edge over synthetic and bio-based polymers, due to their biodegradability in addition to other interesting properties. Proteins can be utilized to create such materials with specific functional characteristics. We report the preparation of transparent human serum albumin thin films in presence of CTAB-capped gold nanorods with different compositions of protein as well as the plasticizer i.e., sorbitol. The mechanical properties, surface topology, morphology, molecular structure, moisture content, total soluble material, biodegradability, antibacterial activity and optical properties have been investigated. Gold nanorods act as crosslinkers and sorbitol as a plasticizer increases plasticity and hardness of the films. The films deposited are biodegradable, water soluble and flexible in nature. AFM images reveal a pattern on the surface with different average heights with an increase in surface roughness with the addition of sorbitol. NINT studies show increased hardness and elastic modulus with the same amount of sorbitol but higher amounts of protein. Fourier Transform Infrared spectroscopy studies indicate the change in molecular structure of the films, in terms of a change in the hydrogen bonding network that impacts the water content and hardness of the films. Most importantly the films show antibacterial property, modulated by the composition used. The interesting features and the enhanced mechanical properties pave the path for potential applications of the films. The study shows that the optimization of the composition is crucial to achieve the desired film material with required properties.

Removal of Heavy Metal Ions from Water Using Chelating Copolymer Resin-IV Derived from 2-Hydroxy, 4-Methoxybenzophenone, 1, 5-Diaminonaphthalene and Formaldehyde

The resin 2-H, 4-MBP-1,5-DANF-IV was synthesized by the condensation of 2-hydroxy, 4-methoxybenzophenone and1, 5-diaminonaphthalene with formaldehyde in the presence of hydrochloric acid as a catalyst. The resin was characterized by elemental analysis, infrared (IR) spectroscopy, nuclear magnetic resonance (NMR) spectroscopy and UV-Visible spectral studies. The chelation ion-exchange properties was studied for Ni2+, Cu2+, Co2+, Zn2+ and Pb2+ ions employing a batch equilibrium method. It was used to study of the selectivity of metal-ion uptake involving the measurements of the distribution of a given metal ion between the copolymer sample and a solution containing the metal ion. The study was carried out over a wide pH range and in media of various ionic strength.The resin depicted a higher selectivity for Cu2+ and Ni2+ ion than for Co2+, Zn2+ and Pb2+ ions.

Modulating Whey Proteins Antigenicity with Lactobacillus delbrueckii subsp. bulgaricus DLPU F-36 Metabolites: Insights from Spectroscopic and Molecular Docking Studies.

Numerous studies have highlighted the potential of Lactic acid bacteria (LAB) fermentation of whey proteins for alleviating allergies. Nonetheless, the impact of LAB-derived metabolites on whey proteins antigenicity during fermentation remains uncertain. Our objective was to elucidate the impact of small molecular metabolites on the antigenicity of α-lactalbumin (α-LA) and β-lactoglobulin (β-LG). Through metabolomic analysis, we picked 13 bioactive small molecule metabolites from Lactobacillus delbrueckii subsp. bulgaricus DLPU F-36 for coincubation with α-LA and β-LG, respectively. The outcomes revealed that valine, arginine, benzoic acid, 2-keto butyric acid, and glutaric acid significantly diminished the sensitization potential of α-LA and β-LG, respectively. Moreover, chromatographic analyses unveiled the varying influence of small molecular metabolites on the structure of α-LA and β-LG, respectively. Notably, molecular docking underscored that the primary active sites of α-LA and β-LG involved in protein binding to IgE antibodies aligned with the interaction sites of small molecular metabolites. In essence, LAB-produced metabolites wield a substantial influence on the antigenic properties of whey proteins.

Synthesis and characterization of Xanthan Gum Xanthates and their application for toxic metal ion removal from synthetic wastewater

This study focuses on the synthesis of three grades of xanthates of natural polymeric material Xanthan gum (XG) by reacting it with Carbon disulfide (CS2) in basic medium at room temperature under inert atmosphere. The confirmation of the formation of Xanthan Gum Xanthates (XGX) has been done with the help of Ultraviolet (UV) spectroscopy, Fourier Transform Infrared (FTIR) spectroscopy, point of zero-charge (PZC), Scanning Electron Microscopy and Energy Dispersive Spectroscopy (SEM-EDS) studies. DSC and XRD studies have been done to confirm the crystalline nature of the xanthates. The removal of Cu2+and Co2+ from the prepared grades was found to be 86.7%, 89.9% and 93.6% for Cu2+ and 86.1%, 88.8% and 93.1% for Co2+ respectively. Therefore, these xanthates can be employed for the eradication of such toxic metal ions from their synthetic solutions. The adsorption capacities of three grades of xanthates viz. XGX1, XGX2, and XGX3 were found to be 319.48, 303.03, and 325.73 mg/g for Cu(II) and 238.66, 246.91, and 230.41 mg/g and for Co(II) respectively, which are better than the adsorption capacities reported for various other adsorbents in literature.

Thermal and spectroscopic (IR, NMR) studies of bulk ammonia borane – Polyethylene oxide composites: A potential hydrogen storage system

We utilized differential scanning calorimeter (DSC), Fourier-transformed infrared spectroscopy (FT-IR), and solid-state nuclear magnetic resonance spectroscopy (NMR) techniques to understand the dehydrogenation mechanism of ammonia borane (AB) and its polymer composites. The results indicated that the polymeric composites with higher polyethylene oxide (PEO) mass ratio involve the possible breakdown of dative bond and the formation of new interaction (H-bonding) between the AB and the polymer. The activation energies were calculated in the temperature range of 25 °C and 300 °C which were found to be lower than the pristine AB. 15N and 11B NMR studies at room temperature showed evidence for a possible interaction, H-bonding, between AB and PEO. The NMR experiments at 85 °C were conducted to investigate the isothermal decomposition during several hours. Results indicated that the pristine AB takes longer incubation time, however the polymeric composite readily decomposes at 85 °C. Both showed proof for the formation of byproducts. Moreover, IR study showed evidence to support the interaction between AB and PEO.

π-Bonding of Group 11 Metals to a Tantalum Alkylidyne Alkyl Complex Promotes Unusual Tautomerism to Bis-alkylidene and CO2 to Ketenyl Transformation.

A salt metathesis synthetic strategy is used to access rare tantalum/coinage metal (Cu, Ag, Au) heterobimetallic complexes. Specifically, complex [Li(THF)2][Ta(CtBu)(CH2tBu)3], 1, reacts with (IPr)MCl (M = Cu, Ag, Au, IPr = 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene) to afford the alkylidyne-bridged species [Ta(CH2tBu)3(μ-CtBu)M(IPr)] 2-M. Interestingly, π-bonding of group 11 metals to the Ta─C moiety promotes a rare alkylidyne alkyl to bis-alkylidene tautomerism, in which compounds 2-M are in equilibrium with [Ta(CHtBu)(CH2tBu)2(μ-CHtBu)M(IPr)] 3-M. This equilibrium was studied in detail using NMR spectroscopy and computational studies. This reveals that the equilibrium position is strongly dependent on the nature of the coinage metal going down the group 11 triad, thus offering a new valuable avenue for controlling this phenomenon. Furthermore, we show that these uncommon bimetallic couples could open attractive opportunities for synergistic reactivity. We notably report an uncommon deoxygenative carbyne transfer to CO2 resulting in rare examples of coinage metal ketenyl species, (tBuCCO)M(IPr), 4-M (M = Cu, Ag, Au). In the case of the Ta/Li analogue 1, the bis(alkylidene) tautomer is not detected, and the reaction with CO2 does not cleanly yield ketenyl species, which highlights the pivotal role played by the coinage metal partner in controlling these unconventional reactions.

Correlation of the properties of quasi-ternary Ni-based superalloys computed from DFT to elemental properties enabling predictions on the behavior of metallic alloying elements

Research on multicomponent superalloys derived from Ni3Al shows that certain elemental additions congregate at the boundary of the γ/γ′ interface while certain others partition into either the γ or the γ′ phases. Such microstructural features have a strong bearing on the performance of the superalloy. However, no established correlations exist as of now, that can help predict such a behavior. The present work addresses this issue by examining the properties of the quasi-ternary alloys of Ni3Al and brings out correlations to selected lumped parameters related to the elemental properties. Computation of thermodynamic properties of 11 alloys of quasi-ternary Ni24Al7X system was carried out from first principles using Wien 2k and Gibbs2 code on a supercell constructed with 32 atoms. Elements X substituted at the Al site are selected from the information derived from the literature. Systematic variations are shown to occur in compressibility and heat of formation ΔH of the alloys with average electron concentration, elemental radii and/or electronegativity of the constituent elements in the alloys. Analysis of the data computed for a supercell on ΔH of quasi-ternary Ni31X alloys of Ni (the γ phase) and the ΔH of Ni24Al7X alloys (the γ′ phase) explains the possible reason for the enrichment of elements like Re and W at the γ/ γ′ interface. Trends in the observed correlations correctly predict the experimental observations on alloying effects reported from spectroscopic studies on quasi-ternary alloys of Ni3Al. The scope of predicting alloying behavior based on basic elemental properties gains significance in the design of superalloys.

Synthesis, Stability, Meisenheimer Complex Formation, and Charge‐Transfer Properties of Ultra‐Electron‐Deficient Tetracyano‐Naphthalene Diimides

AbstractTetra‐cyano substituted naphthalene diimides (TCNDIs) with calculated LUMO of −5.2 eV, form one of the strongest electron‐acceptors known to date. However, the synthesis and isolation of this class of molecules remain challenging due to its reactivity emanating from its ultra‐electron‐deficiency. Herein we have established an improved synthetic methodology of TCNDIs with cost‐effective reagents and circumventing metallic catalysts. The synthesis is amenable to TCNDIs with the shortest axial alkyl groups, i. e., methyl group and also longer alkyl chains. We also gained insight on how axial alkyl chain lengths influence electron‐deficiency, Meisenheimer complex formation, reactivity, and charge‐transfer of TCNDIs from computation, spectroscopy, and electrochemical studies. The TCNDIs with Me/Et axial groups were found to be more susceptible to moist solvents vis‐à‐vis the TCNDIs with longer alkyl groups. The single crystal structures of the TCNDIs show infinitely π‐stacked structure, and a new C=O ⋅ ⋅ ⋅ C≡N or C≡N ⋅ ⋅ ⋅ π motif is discerned. Finally, toluene‐mediated charge‐transfer properties of TCNDIs in the single crystals as well as in solution have been examined.

Symmetry‐breaking of Dibenzo[b,d]thiophene Sulfone Enhancing Polaron Generation for Boosted Photocatalytic Hydrogen Evolution

AbstractThe current bottleneck in the development of efficient photocatalysts for hydrogen evolution is the limited availability of high‐performance acceptor units. Over the past nine years, dibenzo[b,d]thiophene sulfone (DBS) has been the preferred choice for the acceptor unit. Despite extensive exploration of alternative structures as potential replacements for DBS, a superior substitute remains elusive. In this study, a symmetry‐breaking strategy was employed on DBS to develop a novel acceptor unit, BBTT‐1SO. The asymmetric structure of BBTT‐1SO proved beneficial for increasing multiple moment and polarizability. BBTT‐1SO‐containing polymers showed higher efficiencies for hydrogen evolution than their DBS‐containing counterparts by up to 166 %. PBBTT‐1SO exhibited an excellent hydrogen evolution rate (HER) of 222.03 mmol g−1 h−1 and an apparent quantum yield of 27.5 % at 500 nm. Transient spectroscopic studies indicated that the BBTT‐1SO‐based polymers facilitated electron polaron formation, which explains their superior HERs. PBBTT‐1SO also showed 14 % higher HER in natural seawater splitting than that in deionized water splitting. Molecular dynamics simulations highlighted the enhanced water‐PBBTT‐1SO polymer interactions in salt‐containing solutions. This study presents a pioneering example of a substitute acceptor unit for DBS in the construction of high‐performance photocatalysts for hydrogen evolution.

Symmetry-breaking of Dibenzo[b,d]thiophene Sulfone Enhancing Polaron Generation for Boosted Photocatalytic Hydrogen Evolution.

The current bottleneck in the development of efficient photocatalysts for hydrogen evolution is the limited availability of high-performance acceptor units. Over the past nine years, dibenzo[b,d]thiophene sulfone (DBS) has been the preferred choice for the acceptor unit. Despite extensive exploration of alternative structures as potential replacements for DBS, a superior substitute remains elusive. In this study, a symmetry-breaking strategy was employed on DBS to develop a novel acceptor unit, BBTT-1SO. The asymmetric structure of BBTT-1SO proved beneficial for increasing multiple moment and polarizability. BBTT-1SO-containing polymers showed higher efficiencies for hydrogen evolution than their DBS-containing counterparts by up to 166 %. PBBTT-1SO exhibited an excellent hydrogen evolution rate (HER) of 222.03 mmol g-1 h-1 and an apparent quantum yield of 27.5 % at 500 nm. Transient spectroscopic studies indicated that the BBTT-1SO-based polymers facilitated electron polaron formation, which explains their superior HERs. PBBTT-1SO also showed 14 % higher HER in natural seawater splitting than that in deionized water splitting. Molecular dynamics simulations highlighted the enhanced water-PBBTT-1SO polymer interactions in salt-containing solutions. This study presents a pioneering example of a substitute acceptor unit for DBS in the construction of high-performance photocatalysts for hydrogen evolution.