ZnO nanoparticles doped with Li (Zn 1Ày Li y O, y 0.1) have been investigated with emphasis on the correlation between their magnetic, electronic, and structural properties. In particular, defects such as interstitial Li and Zn atoms, substitutional Li atoms, and oxygen vacancies have been identified by X-ray photoelectron spectroscopy (XPS) and their respective roles in stabilization of the magnetic moment are discussed. X-ray diffraction (XRD) and XPS give clear evidence of Li presence at both substitutional and interstitial sites. XPS studies further show that the amount of substitutional Li defects (Li zn) and interstitial Li defects (Li i) vary non-monotonically with the Li concentration, with the Li i defects being noticeably high for the y ¼ 0.02, 0.08, and 0.10 concentrations, in agreement with the XRD results. Magnetization studies show room temperature ferromagnetism in these nanoparticles with the moment being largest for the particles with high concentration of interstitial lithium and vice versa. Both interstitial Zn (Zn i) defects and Zn-O bonds were determined from the Zn LMM Auger peaks; however, the variation of these with Li concentrations was not large. Oxygen vacancies (V o) concentrations are estimated to be relatively constant over the entire Li concentration range. We relate the Li i and Zn i defects to the formation and stabilization of Zn vacancies and thus stabilizing the p-type ferromagnetism predicted for cation (zinc) vacancy in the ZnO type oxides. V

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Li co-doped ZnO:Co (Zn0.96-yCo0.04LiyO , y ≤ 0.1) nanoparticles were synthesized by the sol-gel technique and the correlation between the structural, electronic and magnetic properties was investigated. All the samples show a single phase hexagonal (wurtzite) ZnO structure and no secondary phases were detected. Variational trends in lattice parameters suggest the incorporation of Li in the ZnO:Co system in both substitutional and interstitial sites. Detailed electronic studies have been performed by high-resolution x-ray photoelectron spectroscopy (XPS) to determine the states of Zn, O, Co and Li. It was determined that Co substitutes at Zn sites (CoZn) while the O vacancy and Zn defects did not show much variation with increasing Li concentration. Deconvolution of the Li XPS peak showed a clear non-monotonic trend in the variation of the substitutional Li (LiZn) and interstitial Li (Lii) defects with increasing Li concentration in the particles. The magnetization study of the samples showed that the variation of the moment closely followed the trend of variation of the LiZn defects. The data are interpreted in terms of substitutional Li acting as a hole dopant and optimizing the conditions for ferromagnetism in Co-doped ZnO. Interstitial Li is not seen to be playing this role.

We report the very first example of a catalyst based on a ternary composite of graphitic carbonitride (g‐C3N4), ceria (CeO2) and magnetite (Fe3O4) for overall water splitting in 1.0 M KOH. Synergy between the components due to electronic effects results in a highly efficient catalyst which catalyzes Oxygen Evolution Reaction (OER) and Hydrogen Evolution Reaction (HER) at substantially low overpotentials (400 mV and 310 mV respectively) to produce benchmark current density (10 mA cm−2). OER activity of the catalysts surpasses that of the benchmark RuO2 catalyst at higher current densities (≥50 mA cm−2). The composite catalyst is stable and shows a Faraday efficiency of 98 % for OER. Overall water splitting was achieved at an overpotential of 1.94 V which is substantially high at 1 wt % loading of active metal.

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