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In this study, pure ZnO and iron (Fe) and cobalt (Co) co-doped ZnO nanoparticles were synthesized by varying Fe and Co concentrations using the co-precipitation method. The physical properties of as-prepared samples were investigated through XRD, FTIR, SEM, and UV–vis spectroscopy. X-ray diffraction confirmed the strong influence of Fe and Co ions on structural parameters without disturbing the basic ZnO hexagonal structure. The microstructural study was executed by using the Scherrer, W–H, and SSP methods. FTIR confirmed the presence of Zn–O, and Zn–M–O (M = Fe, Co) vibrational modes, which further confirmed the successful incorporation of dopants ions. The energy bandgap (E g) extracted from UV–vis spectra has shown red-shift (3.37–2.7 eV) for decreasing Fe contents, whereas blue-shift (3.37–3.39 eV) for increasing Co concentration. SEM was used to investigate surface morphology, which represents the high rate of agglomeration. The photocatalytic test was performed on grown samples against various dyes and also observed the effects of varying concentrations of Fe and Co ions. The maximum degradation efficiency (98.8%) at 6%Fe and 4%Co under direct sunlight in 60 min against methylene blue (MB) was achieved. The photocatalytic activity of optimized concentration (6%Fe and 4%Co) was further tested against cresol red (CR), methyl orange (MO), safranin-O (SO), rhodamine-B (RhB), and methyl red (MR) dyes. The maximum degradation efficiency against MR dye (96.0%) was observed. The antibacterial test against Staphylococcus aureus and Klebsiella pneumoniae bacterial strains have shown that co-doped ZnO nanoparticles have a higher activity as compared to pristine ZnO, and furthermore, the sample with 6%Fe and 4%Co concentration exposed the highest antibacterial actively for both bacterial strains. [ABSTRACT FROM AUTHOR]

Non-noble metal containing catalysts for oxygen reduction reaction (ORR) are being targeted due to their low cost and availability. The rarity, high-cost, and self-poisoning of noble metals are the main drawbacks for the large-scale applications. Herein, a facile and simple synthetic strategy is adopted to prepare non-noble metal-based nitrogen doped carbon nanotubes (N-CNTs). The cobalt oxides (CoOx) nanoparticles are in-situ encapsulated inside these N-CNTs which are then treated with acid (HCl) and phosphidized to obtain CoOx-CoP/N-CNTs. High resolution transmission electron spectroscopy (HR-TEM) results reveal that the ends of N-CNTs are closed with nanoparticles. X-ray photoelectron spectroscopy (XPS) confirms the presence of cobalt oxide and cobalt phosphide nanoparticles. The catalyst CoOx-CoP/N-CNTs2 demonstrated E onset and E 1/2 of 0.96 V and 0.81 V, respectively in alkaline environment which is very much comparable to the state of art catalyst (20 wt% Pt/C). Acid treatment significantly enhances the electrocatalytic activity for ORR in comparison to material synthesized without prior treatment with acid. The catalyst exhibits excellent durability over 10,000 cycles and methanol tolerance to 0.5 M methanol addition. The enhanced ORR activity is attributed to synergistic effect of carbon matrix and encapsulated nanoparticles. • Cobalt oxides (CoOx) nanoparticles are in-situ encapsulated inside N-CNTs. • CoOx/N-CNTs treated with acid (HCl) and phosphidized to obtain CoOx-CoP/N-CNTs. • High resolution transmission electron spectroscopy results reveal that the ends of N-CNTs are closed with nanoparticles. • CoOx-CoP/N-CNTs2 demonstrated E onset and E 1/2 of 0.96 V and 0.81 V, respectively in alkaline environment. • The catalyst exhibited excellent durability over 10,000 cycles and methanol tolerance to 0.5 M methanol addition. [ABSTRACT FROM AUTHOR]

• Pt/Er nanoparticles are decorated on Cd-MOF derived hierarchical carbon. • Pt-Er@PCN-900 shows wide range porosity and large active sites. • Pt-Er@PCN-900 presented excellent ORR and HER catalytic activity. • Stability and durability of Pt-Er@PCN-900 is marvelous in alkaline media. Fabrication of Pt alloy with controlled morphology and size has drawn an attractive attention in developing active electrocatalysts for fuel cell and water splitting application. However, the effectively controlled synthesis strategy and morphology on N-doped carbon structure is still a challenging issue. Herein, a facile strategy for uniform dispersion of active sites of Pt/Er on the hierarchical N-doped carbon structure through pyrolysis in innert atmosphere is addopted. The developed product of Pt-Er@PCN-900 has exhibited efficacious trifunctional catalytic activity for hydrogen/oxygen evolution as well as oxygen reduction reaction. Comparatively, Pt-Er@PCN-900 with 8% Pt presents excellent performance than commercial 20%Pt/C. The present work highlights the importance of the rationalized dispersion of Pt/Er active sites for the future large-scale commercial applications of fuel cell and water splitting. [ABSTRACT FROM AUTHOR]

In this study, the micro-emulsion approach was adopted to fabricate rare earth (Nd) and transition metal (Cu) co-doped barium hexaferrite (Ba 1-x Nd x Fe 12-y Cu y O 19) nanoparticles (NPs). The fabricated co-doped and undoped materials were characterized by FTIR, XRD, and SEM techniques for structural and morphological investigation. Structural studies such as XRD and FTIR confirmed Nd and Cu doping at the tetrahedral and octahedral sites of barium hexaferrite, respectively. The SEM analysis made sure that the materials were successfully produced at the nanoscale. Dielectric measurements revealed that the dielectric constant and AC conductivity values of the co-doped sample were higher than those of the undoped sample. The VSM study confirms the improved magnetic properties of the sample after co-doping that facilitates its separation and reuse after photocatalytic experiments. The co-doped and undoped sample's photocatalytic activities (PCA) were explored by comparing their Methyl Green (MG) dye degradation efficiencies. The results revealed that the co-doped barium hexaferrite sample degraded almost 92.6% of the MG dye, while the undoped sample degraded just 37.4%. The higher PCA of the co-doped sample is credited to its structural defects, which adjust the band interval to increase electrical conductivity. In addition, the co-doped sample lost only 2% photocatalytic efficiency after five successive cycles, demonstrating its potential for reuse. Application studies have clearly shown that our Nd-Cu co-doped barium hexaferrite sample has a great potential for practical application to remove toxic dyes from the environment. [Display omitted] [ABSTRACT FROM AUTHOR]