Understanding and exploring the decisive factors responsible for superlative catalytic efficiency is necessary to formulate active electrode materials for improved electrocatalysis and high-throughput sensing. This research demonstrates the ability of bud-shaped gold nanoflowers (AuNFs), intermediates in the bud-to-blossom gold nanoflower synthesis, to offer remarkable electrocatalytic efficiency in the oxidation of ascorbic acid (AA) at nanomolar concentrations. Multicomponent sensing in a single potential sweep is measured using differential pulse voltammetry while the kinetic parameters are estimated using electrochemical impedance spectroscopy. The outstanding catalytic activity of bud-structured AuNF [iAuNFp(Bud)/iGCp ≅ 100] compared with other bud-to-blossom intermediate nanostructures is explained by studying their structural transitions, charge distributions, crystalline patterns, and intrinsic irregularities/defects. Detailed microscopic analysis shows that density of crystal defects, such as edges, terraces, steps, ledges, kinks, and dislocation, plays a major role in producing the high catalytic efficiency. An associated ab initio simulation provides necessary support for the projected role of different crystal facets as selective catalytic sites. Density functional theory corroborates the appearance of inter- and intra-molecular hydrogen bonding within AA molecules to control the resultant fingerprint peak potentials at variable concentrations. Bud-structured AuNF facilitates AA detection at nanomolar levels in a multicomponent pathological sample.

Polyvinylpyrrolidone (PVP)-based silver nanoprisms (AgNPrs) show an initial stacking geometry because of their low zeta potential and electrostatic interaction between face-to-face energetically stable {111} surface-bound pyrrolidone groups through the Na + -ioninduced cation−π interaction. Congested interplanar space between AgNPrs allows As(III) to react differentially with silver atoms from facial {111} and peripheral {110} facets to result in smaller stackings and finally nanoseeds. Above this critical concentration of As(III), PVP leached out from nanoparticles to form nanoseed-engulfed emulsions and induced controlled aggregation. This entire morphological transition has been decoded by recording their surface plasmon and surfaceenhanced Raman scattering tuning and confirmed by the transmission electron microscopy study. Strong affinity and selectivity of As(III) toward the Ag atom (verified and estimated by the HF/3-21g* level of density functional theory calculation) coupled with low-cost colorimetry provide us a versatile assay with potential application in the environmental protection drive.

With an increasing demand for clean and sustainable energy which is directly related to water splitting, regenerative fuel cells, metal-air batteries, etc., exploring an efficient and inexpensive electrocatalyst with highly stable for oxygen evolution reaction (OER) is very important. In this article, here we demonstrated the nanorod Zn-Co-Te, is found to be a very good electrocatalyst for oxygen evolution reaction (OER) in alkali medium (KOH, pH = 15.14) with onset potential 1.38 V vs RHE. When this catalyst used as an electrocatalyst Zn-Co-Te nanorod obtained low overpotential 221 mV at a 10 mAcm−2 current density with Tafel slope 91 mV/dec and high stability within three months.

A void-enriched and highly strained porous Au−Ag nanoalloy (NP alloy ) has been synthesized from Au−Ag core−shell nanostructure by employing a galvanic replacement reaction and introducing Kirkendall voids in it. Obtained NP alloy acts both as an efficient cathodic and anodic material for methanol, ethylene glycol, and glycerol oxidation as well as oxygen reduction reactions simultaneously in an alkaline medium. High catalytic efficacy (low onset potential (E on ) and high current density (j)), wide thermal stability, and positive alcohol tolerance response of NP alloy sets them as a practical bifunctional electrode coating alternative compared to Pt/C in designing an efficient alkaline direct alcohol fuel cell.

This report quantitatively investigates the role of grain-boundary and grain size in the excellent electrocatalytic activity of our recently synthesized shape-engineered (bud-shaped AuNP50 to bloom or flower-shaped AuNP75 to over-bloomed AuNP150) and differential grain-boundary enriched anisotropic flower-like gold nanostructures for the hydrogen evolution reaction (HER). All the synthesized anisotropic gold nanoparticles (AnGNPs) and especially the AuNP75 exhibit outstanding catalytic activities (in terms of both overpotential and turnover frequency) toward HER in different pH media compared to that of normal spherical-shaped gold nanoparticles (e.g., TSC-capped 25 nm AuNPsphs) in similar physical conditions. Further, the theoretical calculation based on density functional theory (DFT) nicely corroborates with the experimental findings and discloses the effective contribution of grain-boundaries toward the free energy of hydrogen adsorption (ΔG H*) and the position of the d-band center, which play a crucial role in their HER activities.