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Photoanode is an essential part in dye sensitized solar cells (DSSC). Semiconductor materials, such as TiO2, ZnO, and SnO2, are commonly used as photoanode material. In this study, DSSC photoanode was fabricated using TiO2 obtained from Bangka ilmenite concentrate by caustic fusion method followed by water leaching, acid leaching, and sol-gel reactions. The synthesized TiO2 powder has an anatase phase with a crystal size of 9.55 nm, band gap energy of 3.0 eV, spherical morphology with an average particle size of 0.53 μm, and a specific area of 138.39 m2/g. The synthesized TiO2 powder was found to have Fe impurities. The DSSC with TiO2 photoanode synthesized in this work produced current-voltage characteristics with photoconversion efficiency of 0.75%.

In this work, coconut shell was used as raw material to. Dried coconut shells were burned in a close compartment to form coconut charcoal. The dried carbon was further washed with hot distilled water to obtain a pH 7 and was dried again in an oven at 100 °C for 12 hours. The carbon was further pyrolyzed at two temperature variations, i.e. at 400 °C and 1400 °C, under argon environment for two hours before being cooled to room temperature and ready for characterization. The X-ray diffraction result showed that there are two prominent peaks centred around 2θ 25° and 43°, whereas the scanning electron microscopy result showed the flakes microstructure with long range size variation. The energy dispersive X-ray spectroscopy showed that the composition of sample pyrolyzed at 400° C has 59-85 % carbon 7-37 % oxygen and 0.02-0.93 other elements (Si, P, Cl, K, Ti and Ni), whereas the sample pyrolyzed at 1400 °C has 88-92 % carbon, 7.8-11.7 % oxygen and 0.01-0.4 % other elements. This result showed that the coconut shell has the potential to be used as a cheap raw material for synthesizing nanocarbon using a simple method.

The effect of Zn substitution to the Cu-spin fluctuation in Eu1.85Ce0.15Cu1-yZnyO4+α-δ with y = 0, 0.01, 0.02, and 0.05 has been studied from zero-field (ZF) muon-spin-relaxation (μSR) measurements to understand Zn-induced magnetic state in electron-doped high-Tc superconducting cuprates. It was found that the Cu-spin correlation was developed through Zn substitution. These results were similar to the results of ZF-SR measurements in the holedoped cuprates La2-x Sr x Cu1-y Zn y O4, leading to the view electron-hole doping symmetry in high-Tc superconductors.

Electron-doped superconducting cuprate of Eu1.85Ce0.15CuO4+α−δ (ECCO) has been successfully synthesized in various annealing condition in order to investigate the dependence of oxygen content (δ) with their physical properties, namely, structure, transport and magnetic properties. The value of δ is estimated from weight changes before and after annealing process. XRD, temperature dependence of resistivity and dc magnetic susceptibility measurements were performed to study structure, transport and magnetic properties, respectively. For samples with δ values smaller than 0.095, tetragonal T’ structure that similar with other electron-doped superconducting system is observed. From resistivity measurement, the trace of superconductivity is starting observed in the samples with δ values larger than 0.02. From dc magnetic susceptibility data, it is found that the highest Tc onset of 11.5 K is observed in the samples with δ value of 0.041.

The effect of partially substitution of magnetic impurity Fe for Cu to the magnetic and transport properties in electron-doped superconducting cuprates of Eu1.85+yCe0.15-yCu1-yFeyO4+α-δ (ECCFO) with y = 0, 0.010, 0.020, and 0.050 has been studied, in order to investigate the mechanism of magnetic and transport properties of ECCFO in normal-state. Magnetic properties are investigated by DC magnetic-susceptibility measurements that carried out at low temperatures down to 2 K using a standard SQUID magnetometer in a magnetic field of 5 Oe on field cooling. Transport properties addressed to electron mobility, are extracted from radius of electron localization calculated from temperature dependence of resistivity. For y = 0, temperature dependence of dc magnetic-susceptibility (χ) indicated the change of magnetic behavior from paramagnetic to diamagnetic below 15 K. Above 15 K, all samples show paramagnetic behavior with the values of magnetic moment in every volume unit increased with increasing y. Electron mobility decreased with increasing y., {"references":["T. Adachi, S. Yairi, K. Takahashi, Y. Koike, I. Watanabe, and K.\nNagamine, Phys. Rev. B 69 (2004) 184507.","Risdiana, T. Adachi, N. Oki, S. Yairi, Y. Tanabe, K. Omori, T. Suzuki, I.\nWatanabe, A. Koda, W. Higemoto and Y. Koike, Phys. Rev. B 77 (2008)\n054516.","Risdiana, T. Adachi, N. Oki, Y. Koike, T. Suzuki, I. Watanabe, Phys.\nRev. B 82 (2010) 014506.","Risdiana, T. Adachi, Y. Koike, I. Watanabe and K. Nagamine (2005)\nPhysica C 426-431, 355.","J. M. Tarascon, E. Wang, S. Kievelson, B. G. Bagley, G. W. Hull, R.\nRamesh (1990) Phys. Rev. B 42, 218.","Y. Koike, N. Watanabe, T. Noji, Y. Saito, Solid State Commun. 78 (1991)\n511.","K. M. Suzuki, T. Adachi, Y. Tanabe, H. Sato, Risdiana, Y. Ishii, T.\nSuzuki, I. Watanabe, Y. Koike (2012) Physical Review B 86, 014522.","Risdiana, L. Safriani, W. A. Somantri, T. Saragi, T. Adachi, I. Kawasaki,\nI. Watanabe, Y. Koike (2014) Advanced Materials Research 896, 354.","N. F. Mott, Metal Insulator Transition, Taylor & Francis Inc., 1974."]}