A green and facile method for the synthesis of gold nanoparticles (AuNPs) was developed. Phytochemicals from the aqueous extract of Fagonia indica were used to reduce and stabilize gold precursor (HAuCl₄) into gold nanoparticles. Various analytical techniques were used to determine size, morphology, composition, crystallinity, and capping biomolecules of the prepared gold nanoparticles. The appearance of characteristic surface plasmon resonance peak (SPR) at 542–565 nm revealed the synthesis of AuNPs (UV-Vis spectroscopy). XRD and EDX studies confirmed the face centered cubic structure and elemental composition of the green synthesized gold nanoparticles. Average particle sizes of 50, 20, and 70 nm were obtained by using the plant concentrations of 5, 10, and 15 mL respectively, with a fixed amount of HAuCl₄ (2 mM). The effect of synthesis variables (amount of plant extract and HAuCl₄) on the gold nanoparticles was also studied. Under the optimized conditions (10 mL plant extract + 2 mM HAuCl₄ and pH 8) the biogenic gold nanoparticles were well dispersed, small sized (15–20 nm), and mostly hexagonal in shapes. These Fagonia indica mediated Au-nanoparticles were observed to have strong catalytic activity for the photocatalytic reduction of methylene blue and chemical reduction of 4-nitrophenol. 80% of MB could be photodegraded under visible-light irradiation after 80 min, showing the excellent photocatalytic activity of biogenic gold nanoparticles. Moreover, the catalytic activity was found to be size dependent. Cyclic voltammetry (CV) indicated the electrochemical reversible oxidation of catechol at the green synthesized Au-NPs modified glassy carbon electrode. The Au-NPs modified electrode showed excellent catalytic activity with strong stability toward the electrochemical oxidation of catechol.

Lithium ion batteries are considered to be smart power sources for applications in a broad range of portable electronics and fast-growing electric vehicles. However, the existing electrode system suffers from a limited lifespan triggered by lithium alloying agglomeration, which affects the full-scale reversible insertion of Li⁺ into the anode material. The discovery of novel alternative strategies that could improve the lifespan and rate performance of active electrode materials is of immense importance. Herein, we fabricated two semiconductor metalloids, selenium and tellurium, into a 1D architecture (Se/Te nanorods) and subsequently wrapped in reduced graphene oxide (rGO) nanosheets. The designed Se/Te nanorods at GO material is named Se/Te@rGO composite and investigated as the anode material for Li⁺ ion batteries. The Se/Te@rGO electrode showed an exceptional reversible storage capacity of 1456 mA h g⁻¹ as compared to SeNr (400 mA h g⁻¹) and Se/TeNr (800 mA h g⁻¹) at 0.1 A g⁻¹ after 100 cycles. Furthermore, when cycled at 5 A g⁻¹, the Se/Te@rGO electrode showed an initial specific capacity of 804 mA h g⁻¹ and retained a high specific capacity of 704 mA h g⁻¹ after 3000 cycles (99.5% C.E), indicating the superior performance of the newly fabricated hybrid material. The improved electrochemical storage performance of the Se/Te@rGO electrode material could be ascribed to the 1D Se/Te nanorod architecture, which can provide a short diffusion path for Li-ions and buffer the strain produced during charge–discharge cycles. The incorporated 2D rGO template further enhanced the mechanical strength of the active Se/Te material and suppressed its dissolution and volume expansion during lithiation/delithiation processes. Our contribution highlights substantial progress in the development of high storage materials for applications in long-life Li-ion batteries.