Biosynthesis using plant extract is known as one of the potential techniques to synthesize different zinc oxide nanoparticles (ZnO-NPs) in different size ranges. ZnO-NPs were synthesized using Plumeria leaf extract with laboratory chemical reagent Zn(CH3COO)2 and followed by the micro-encapsulation of biosynthesized ZnO-NPs using chitosan and cellulose with TEOF as a cross-linker employing freeze gelation method. Both neat and encapsulated ZnO-NPs have been characterized by FT-IR, UV spectroscopy, XRD, and SEM techniques. The UV-spectroscopic analysis confirmed the characteristic band of ZnO-NPs at 356.0 nm, and FIIR showed the peaks at 544 cm−1 and 545 cm−1 corresponding to the Zn–O bond. Powder XRD pattern showed the wurtzite structure of ZnO and gave the calculated average crystallite size as of 27.23 nm. In the case of encapsulated ZnO-NPs, the UV–visible spectrum showed two strong absorption peaks at 232.5 nm, 242.5 nm, and a weak peak at 357 nm. A broad peak at 3333 cm−1 in FT-IR spectra is either due to N–H stretching in the amide group of chitosan or hydroxyl group in encapsulated ZnO-NPs. It was observed that chitosan loaded ZnO-NPs had higher entrapment efficiency (81.98%) at 15 mL of plant extract. The kinetic profile in the release of ZnO particles out from encapsulated ZnO-NPs was observed to follow four kinetic paths in 120 min at pH 1.2. The particle release followed the zero-order kinetic in the first 50 min and then followed by Hixson–Crowell kinetic in the next 50 min with two different rate constants, 2.6 × 10−3 min−1 and 13 × 10−3 min−1, before it backs to the zero-order kinetics. This study shows that ZnO nanoparticles can easily be biosynthesized and encapsulated for use in the pharmaceutical industry.

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In the search for novel hydrogen storage materials, neutral silver–copper bimetallic nanoparticles up to the size of eight atoms (Cu m Ag n : m + n ≤ 8) have been computationally studied. Density functional theory with the B3LYP exchange–correlation functional and the combined basis sets of LanL2DZ and aug-cc-pVQZ were used in all of the calculations. H2 adsorption studies on the most stable cluster geometries of all of the neat and heterogeneous entities found that 12 potential candidates, CuAg4, Cu6, Cu5Ag, Cu4Ag2, Cu3Ag3, Cu2Ag4, CuAg6, Cu5Ag3, Cu4Ag4, Cu3Ag5, Cu2Ag6, and CuAg7, fall within the recommended physisorption range of −18 to −6 kJ mol–1. A correlation in the behavior of binding energy, vibrational frequency, average bond distance, highest occupied molecular orbital–lowest unoccupied molecular orbital (HOMO–LUMO) gap, and chemical hardness with H2 adsorption was observed. This analysis further revealed that the H2 adsorption to the cluster was either a parallel or a perpendicular alignment. The analysis of the electron configuration of each atom in the cluster and the H2 molecule and the charge transfer analysis of these 12 clusters also showed that the physisorption in the perpendicular mechanism is due to an induced dipole interaction, while that in the parallel mechanism is due to a weak ionic interaction. The clusters identified with perpendicular adsorption, CuAg4H2, Cu6H2, Cu3Ag3H2, and Cu2Ag4H2, polarized the H2 molecule but had no charge transfer with the H2 molecule and those identified with parallel adsorption, Cu5AgH2, Cu4Ag2H2, CuAg6H2, Cu5Ag3H2, Cu4Ag4H2, Cu3Ag5H2, Cu2Ag6H2, and CuAg7H2, pulled the electrons from the H2 molecule and had charge transfer with the H2 molecule. The shapes of the frontier molecular orbital diagrams of the HOMO and LUMO also followed this observation.

The molecular dynamics (MD) simulation method is used to study Arm(N2)n clusters. Using realistic pair potentials for the argon–argon, nitrogen–nitrogen, and argon–nitrogen interactions, the structures and thermodynamics of these clusters are investigated. The initial focus of the study is the series of thirteen particle clusters of Arm(N2)13−m (0⩽m⩽13). These icosahedral argon–nitrogen clusters display systematic changes in energetics when argon is substituted by nitrogen in the central position. The relative stability of argon-centered clusters over nitrogen-centered clusters is further investigated by defining and calculating a “species-centric” order parameter which can be monitored during a MD simulation. These results are interpreted in terms of frustration effects due to anisotropy in the N2–N2 and N2–Ar potentials. The consequences of these observations for cluster stability and for dynamical behavior, such as melting and evaporation, are investigated. The dynamical studies of larger clusters reveal that the mixed clusters evolve towards a structure with an argon core coated by a nitrogen shell.

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