BiFeO 3 (BFO) is of considerable interest because of its potential applications in the design of devices combining magnetic, electronic, and optical functionalities. Effects of the Gd dopant on the structural, photocatalytic activity, and ferromagnetic properties of BFO nanoparticles have been studied. X-ray diffraction and Raman spectra results of Bi 1-x Gd x FeO 3 (BGFO x , x ) 0, 0.05, 0.1, and 0.15) reflect that the crystal structure of the samples remain stable for x < 0.1, while compositional-driven phase transition from rhombohedral to orthorhombic is observed at x ) 0.1. The photocatalytic activity to decompose Rhodamine-B under visiblelight illumination increases in BGFO x as x increases from zero to 0.1 and then decreases for x ) 0.15. The maximum in photocatalytic activity near the phase boundary of x ) 0.1 is associated with the changing of the polar behavior of the nanoparticles. Comparing with the linear magnetization-magnetic field (M-H) relation in pure BFO nanoparticles, obvious M-H loops can be observed in the doped samples, which are ascribed to the distorted spin cycloid and magnetically active characteristic of Gd 3+ ions.

Because of the existence of interface Schottky barriers and depolarization electric field, ferroelectric films sandwiched between top and bottom electrodes are strongly expected to be used as a new kind of solar cells. However, the photocurrent with a typical order of μA/cm(2) is too low to be practical. Here we demonstrate that the insertion of an n-type cuprous oxide (Cu(2)O) layer between the Pb(Zr,Ti)O(3) (PZT) film and the cathode Pt contact in a ITO/PZT/Pt cell leads to the short-circuit photocurrent increasing 120-fold to 4.80 mA/cm(2) and power conversion efficiency increasing of 72-fold to 0.57% under AM1.5G (100 mW/cm(2)) illumination. Ultraviolet photoemission spectroscopy and dark J-V characteristic show an ohmic contact on Pt/Cu(2)O, an n(+)-n heterojunction on Cu(2)O/PZT and a Schottky barrier on PZT/ITO, which provide a favorable energy level alignment for efficient electron-extraction on the cathode. Our work opens up a promising new method that has the potential for fulfilling cost-effective ferroelectric-film photovoltaic.

Converting light energy to electrical energy in photovoltaic devices relies on the photogenerated electrons and holes separated by the built-in potential in semiconductors. Photo-excited electrons in metal electrodes are usually not considered in this process. Here, we report an enhanced photovoltaic effect in the ferroelectric lanthanum-modified lead zirconate titanate (PLZT) by using low work function metals as the electrodes. We believe that electrons in the metal with low work function could be photo-emitted into PLZT and form the dominant photocurrent in our devices. Under AM1.5 (100 mW/cm2) illumination, the short-circuit current and open-circuit voltage of Mg/PLZT/ITO are about 150 and 2 times of those of Pt/PLZT/ITO, respectively. The photovoltaic response of PLZT capacitor was expanded from ultraviolet to visible spectra, and it may have important impact on design and fabrication of high performance photovoltaic devices based on ferroelectric materials.

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Atomic Ir-doped NiCo layered double hydroxide as a robust bifunctional catalyst for highly efficient and durable overall water splitting.