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Incorporating nanomaterials into hydrogels allows for the creation of versatile materials with properties that can be precisely tailored by manipulating their nanoscale structures, leading to a wide range of bulk properties. Investigating the structural and property characteristics of composite hydrogels is crucial in tailoring their performance for specific applications. This study focuses on investigating the correlation between the structural arrangement and properties of a composite hydrogel of thermoresponsive polymer, gelatin, and light-responsive antimicrobial porous gold nanorods, $PAuNR$. The rheo-mechanical properties of the composite hydrogels are correlated with their nanoscale structural characteristics, investigated using small-angle neutron scattering ($SANS$). Analysis of $SANS$ data reveals a decrease in the fractal dimension of $PAuNRs$ incorporated hydrogel matrix, as compared to pure gelatin. Incorporating $PAuNRs$ results in formation of softer composite hydrogel as evident from decrease in viscoelastic moduli, critical yield strain, denaturation temperature and swelling ratio. Our results demonstrates that the structural modulation at the nanoscale can be precisely controlled through adjusting $PAuNRs$ concentration and temperature providing an fabrication mechanism for hydrogels with desired elastic properties. The reduced elasticity of the composite hydrogel and light sensitive/antimicrobial property of the $PAuNRs$ makes this system suitable for specific biomedical applications, such as tissue engineering, device fabrication and stimuli based controlled drug delivery devices respectively., Comment: Under review: The Journal of Chemical Physics (JCP24-AR-04120)

The interaction between macroscopic fluid flow and nanoscale forces has resulted in the formation of long-range assemblies through evaporation-induced self-assembly. Anisotropic gold nanorods (AuNR) can form disordered, smectic, or vertically ordered long-range structures, but controlling their assembly remains a challenge and requires a deeper understanding of fundamental interaction mechanisms. In this work, we established a correlation between the $in~situ$ drying profiles, measured using an optical tensiometer, and deposit pattern, imaged $ex~situ$ using electron microscopy. Increasing particle concentration induced a transition from coffee-ring to uniform deposition at the microscale, while nanoscale structures shifted from isotropic/smectic to vertically aligned crystalline AuNRs. The interplay of capillary and Marangoni flow influences assembly at both macro and nanoscales, with the deposition process and nanoparticle ordering being highly sensitive to interparticle and nanoparticle-substrate interactions. By systematically studying key parameters, we aim to develop a comprehensive framework for the rational design and fabrication of nanomaterials with precisely controlled structure and properties., Comment: 35 pages including SI, 13 figures including SI, corresponding author: Sunita Srivastava (sunita.srivastava@iitb.ac.in)

The highly efficient photocatalytic water splitting to produce clean energy requires novel semiconductor materials to achieve high solar-to-hydrogen energy conversion efficiency. Herein, the photocatalytic properties of anisotropic $\beta$-PtX$_2$ (X=S, Se) and Janus $\beta$-PtSSe monolayers are investigated based on density functional theory. Small cleavage energy for \{beta}-PtS2 (0.44 J/m2) and $\beta$-PtSe$_2$ (0.40 J/m$^2$) endorses the possibility of their mechanical exfoliation from respective layered bulk material. The calculated results find \{beta}-PtX2 monolayers to have an appropriate bandgap (~1.8-2.6 eV) enclosing the water redox potential, light absorption coefficients (~104 cm$^{-1}$), and excitons binding energy (~0.5-0.7 eV), which facilitates excellent visible-light driven photocatalytic performance. Remarkably, an inherent structural anisotropy leads to the anisotropic and high carrier mobility (up to ~5 x 10$^3$ cm$^2$ V$^{-1}$ S$^{-1}$) leading to fast transport of photogenerated carriers. Notably, the small required external potential to derive hydrogen evolution reaction and oxygen evolution reaction processes with an excellent solar-to-hydrogen energy conversion efficiency of $\beta$-PtSe$_2$ (~16%) and $\beta$-PtSSe (~18%) makes them promising candidates for solar water splitting applications., Comment: 18 pages, 5 figures, Physical Chemistry Chemical Physics, 2022

The improved formulations of the Lindstedt Poincare perturbation method, the harmonic balance method and its modifications using the rational functions, the energy balance method and the two terms Fourier series expansion have been employed to find approximate solution to the equation of motion for the cubic quartic potential AHO and its special cases (the cubic, the quartic, and the purely cubic quartic potential AHOs), to assess the relative merits and demerits of these techniques. Two new rational functions as approximate solution for the harmonic balance method have been proposed and the rational functions have been used as trial functions in the energy balance method for the first time. The time periods T+ (for q(t) > 0), T- (for q(t) < 0) and the total period T so determined have been compared with the corresponding exact values for an extensive range of the AHO parameter values. The results have been thoroughly analysed in terms of their percentage difference from the relevant exact time period. It is concluded that the methods based on the Lindstedt Poincare perturbation approach do not lead to reliable results for T+ and T-, which makes their applicability for the asymmetric potential AHOs doubtful. The harmonic balance technique together with its different variants is the most successful, while the Fourier series approach also yields commendably accurate results. The outcome of the third-order energy balance method is reasonably good though the usage of the rational functions for this has not been encouraging., Comment: 31 pages,9 Tables

We report the results of density functional theory (DFT) based calculations on monolayer and bilayer green phosphorene and their heterostructures with MoSe2. Both monolayer and bilayer green phosphorene are direct band gap semiconductors and possess anisotropic carrier mobility as high as 10^{4} cm^{2}V^{-1}s^{-1}. In bilayers, pressure of about 9 GPa induces the semiconductor-metal transition. Moreover, the band gap depends strongly on the thickness of the films and the external electric field. By employing strain-engineering under suitable solution conditions, monolayer and AC-stacked bilayer green phosphorene offer the band edge alignments which can be used for water splitting. The upper limit of the power conversion efficiencies for monolayer, AB- and AC-stacked bilayer green phosphorene heterostructures with MoSe_{2} is calculated to be 18-21 %. Our results show the possibility of green phosphorene to be used as photocatalytic and photovoltaic material in the energy-related applications., Comment: 23 pages, 7 figures, 2 tables

A few-layer black phosphorene has recently gained significant interest in the scientific community. In this paper, we consider several polymorphs of phosphorene nanoribbons (PNRs) and employ deformation potential theory within the effective mass approximation together with density functional theory to investigate their structural, mechanical and electronic properties. The results show that stability of PNRs strongly depends on the direction along which they can be cut from 2D counterpart. PNRs also exhibit a wide range of line stiffness ranging from 6x10^10 eV/m to 18x10^11 eV/m which has little dependence on the edge passivation. Likewise, the calculated electronic properties of PNRs display them to be either narrow-gap semiconductor (Eg < 1 eV) or wide-gap semiconductor (Eg > 1 eV). The carrier mobility of PNRs is found to be comparable to that of the black phosphorene. Some of the PNRs show n-type (p-type) semiconducting character owing to their higher electron (hole) mobility. Passivation of the edges leads to n-type <-> p-type transition in many of the PNRs considered. The predicted novel characteristics of PNRs with a wide range of mechanical and electronic properties make PNRs to be potentially suitable for the use in nanoscale devices., Comment: 20 pages, 5 figures, 1 table

The van der Waals heterostructures of allotropes of phosphorene (${\alpha}$- and $\beta-P$) with MoSe2 (H-, T-, ZT- and SO-MoSe2) are investigated in the framework of state-of-the-art density functional theory. The semiconducting heterostructures, $\beta$-P /H-MoSe2 and ${\alpha}$-P / H-MoSe2, forms anti-type structures with type I and type II band alignments, respectively, whose bands are tunable with external electric field. ${\alpha}$-P / ZT-MoSe2 and ${\alpha}$-P / SO-MoSe2 form ohmic semiconductor-metal contacts while Schottky barrier in $\beta$-P / T-MoSe2 can be reduced to zero by external electric field to form ohmic contact which is useful to realize high-performance devices. Simulated STM images of given heterostructures reveal that ${\alpha}$-P can be used as a capping layer to differentiate between various allotropes of underlying MoSe2. The dielectric response of considered heterostructures is highly anisotropic in terms of lateral and vertical polarization. The tunable electronic and dielectric response of van der Waals phosphorene/MoSe2 heterostructure may find potentials applications in the fabrication of optoelectronic devices., Comment: 27 pages, 7 figures, 1 table

We explore the structural, electronic, mechanical and thermoelectric properties of a new half Heusler compound, HfPtPb which is all metallic heavy element and has been recently been proposed to be stable [Nature Chem 7 (2015) 308]. In the present work, we employ density functional theory and semiclassical Boltzmann transport equations with constant relaxation time approximation. The mechanical properties such as Shear modulus, Young modulus, elastic constants, Poisson ratio, and shear anisotropy factor are investigated. The elastic and phonon properties reveal that this compound is mechanically and dynamically stable. Pugh and Frantsevich ratio demonstrates the ductile behavior and Shear anisotropic factor reflects the anisotropic nature of HfPtPb. The calculation of band structure predicts that this compound is semiconductor in nature with band gap 0.86 eV. The thermoelectric transport parameters such as Seebeck coefficient, electrical conductivity, and electronic thermal conductivity and lattice thermal conductivity have been calculated as a function of temperature. The highest value of Seebeck coefficient is obtained for n-type doping at optimal carrier concentration. We predict the maximum value of the figure of merit 0.25 at 1000 K. Our investigation suggests that this material is n-type semiconductor., Comment: 14 pages, 5 Figures, 2 Tables