A photoelectrochemical cell was designed that catalyzes the photooxidation of water using visible light as the sole energy source and a molecular catalyst, [Mn(4)O(4)L(6)](+) (1(+), L = bis(methoxyphenyl)phosphinate), synthesized from earth-abundant elements. The essential features include a photochemical charge separation system, [Ru(II)(bipy)(2)(bipy(COO)(2))], adhered to titania-coated FTO conductive glass, and 1(+) embedded within a proton-conducting membrane (Nafion). The complete photoanode represents a functional analogue of the water-oxidizing center of natural photosynthesis.

We report the growth of GdN thin films and a study of their structure and magnetic and conducting properties. It is demonstrated that they are semiconducting at ambient temperature with nitrogen vacancies the dominant dopant. The films are ferromagnetic below 68 K, and a significant narrowing of the band gap is signaled by more than a doubling of its conductivity. The conductivity in the low-temperature ferromagnetic state remains typical of a doped semiconductor, supporting the view that this material is semiconducting in its ground state and that no metal-insulator transition occurs at the Curie temperature.

Most members of the ferromagnetic rare-earth nitride series display doping control over electron transport, with nitrogen vacancies being the most common donor. This paper reports the control and characterization of vacancies in one of the fourteen in the series, DyN. Electrical transport and optical spectra in films with controlled concentrations of vacancies show a pair of in-gap impurity levels ∼ 0.4 eV below the conduction band minimum and a third impurity level that lies nearly coincident with the conduction band minimum. Electron transport is found to be activated for concentrations ≤1019 cm−3, with signatures of extended state conduction at the Fermi level for higher concentrations.