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The present work demonstrates the morphological and Ag doping effects of ZnO electrocatalysts toward electrochemical CO 2 reduction reaction (ECRR). To achieve this, three electrocatalysts, i.e., Nanosphere (0D), Nanorod (1D), and Nanosheet (2D), were synthesized via a facile hydrothermal method, and their ECRR performance was evaluated. As an optimal electrocatalyst, the ZnO Nanorod showed unidirectional growth, higher active surface area and roughness factor compared to Nanosphere and Nanosheet electrocatalysts, which led to a high selectivity for CO up to 68% at a high partial current density of 80 mA•cm −2 , maintaining stable performance up to 4 h. Further, to enhance CO selectivity, the Ag doping strategy is employed. With optimal Ag doping (1.0 atom %) in the ZnO Nanorod electrocatalyst, it showed boosted CO selectivity of 91% at a high partial current density of 93.4 mA•cm −2 with stable performance for up to 10 h. This significant enhancement in the ECRR performance using the ZnO electrocatalyst could be attributed to the morphological features (Nanorod) and the enhanced electronic conductivity with Ag doping. Based on these results, it can be inferred that the simultaneous engineering of morphological features and Ag doping can be an effective way to improve the ECRR performance and CO selectivity.

The novel superparamagnetic nature of magnetic nanoparticles (MNPs) has received significant attention in the wide variety of fields. However, the prerequisites to use these MNPs, particularly in biomedical applications are biocompatibility and high saturation magnetization (Ms). Thus, the development of a sustainable approach for the synthesis of biocompatible MNPs, which utilizes the redox properties of natural compounds from plant extracts, is highly desired. Herein, we have examined the growth of phase selective MNPs synthesized using Azadirachta indica (Neem) extract as a reducing and capping agent. The physical and biological properties of MNPs synthesized with the modified green hydrothermal method at different reaction times and temperatures were investigated. It was observed that the reaction time and temperature strongly modulated the magnetic and structural characteristics of MNPs. At lower reaction time and temperature of 200 °C for 2 h, primarily iron oxalate hydrate (Fe(C2O4).2(H2O)) was formed. Further, with increasing reaction temperature, the phase transformation from iron oxalate hydrate to pure magnetite (Fe3O4) phase was observed. The MNPs prepared with optimum conditions of 220 °C for 4 h show superparamagnetic nature with improved Ms value of 58 emu g−1. The antibacterial study of MNPs against gram-positive bacteria Staphylococcus aureus showed that the MNPs inhibits the growth of bacteria with the least inhibitory MNPs concentration of 6 μl. Thus, the MNPs obtained by this modified biogenic approach will widen the scope and their applicability in future biomedical applications.

While the ever-increasing energy crisis for sustainable and renewable energy sources has prompted the development of innovative materials for photoelectrochemical water oxidation, the techniques to enhance solar-to-hydrogen efficiency and provide long-term stability remain significant challenges. In this work, we report a ternary material system based on reduced graphene oxide (r-GO) and copper–tetracyanoquinodimethane (Cu–TCNQ) decorated on anodically aligned TiO2 nanotubes (TONTs), which simultaneously improve the charge separation and water oxidation kinetics. r-GO and Cu–TCNQ were sequentially decorated on the surface of TONTs by a facile electrophoretic deposition method and marked in brief as TONTs/r-GO/Cu–TCNQ. The fabricated TONT/r-GO/Cu–TCNQ photoanode film was systematically characterized by various techniques, namely, X-ray diffraction (XRD), Raman spectroscopy, Fourier transform infrared spectroscopy, field emission-scanning electron microscopy, field emission-transmission electron microscopy, and X-ray photoelectron spectroscopy. Photoelectrochemical water oxidation was evaluated in 1 M NaOH as an electrolyte, and the TONT/r-GO/Cu–TCNQ photoanode film exhibited a considerably improved J SC (photocurrent density) value of 0.72 mA/cm2 at 1.23 V versus VRHE (reversible hydrogen electrode) compared to the J SC value (0.30 mA/cm2) of bare TONTs. The obtained experimental results demonstrated that r-GO with a high work function and higher electron mobility accepts photogenerated electrons from the conduction band of TONTs and leads to suppressed charge recombination and favorable charge separation/transfer events, whereas Cu–TCNQ acts as an oxygen evolution reaction co-catalyst, which accepts photogenerated holes from the valence band of TONTs, accelerating the surface water oxidation reaction. Additionally, photoluminescence spectroscopy, incident photon-to-current efficiency, Mott–Schottky plot, and electrochemical impedance spectroscopy confirmed that the r-GO and Cu–TCNQ complexes boost the charge separation/transfer events.