Anatase TiO₂ is a typical photocatalyst, and its excellent performance is limited in ultraviolet light range due to its wide band gap of 3.2 eV. A series of Se-doped TiO₂ nanoparticles in anatase structure with various Se concentrations up to 17.1 at.% were prepared using sol-gel method. The doped Se ions are confirmed to be mainly in the valence state of + 4, which provides extra electronic states in the band gap of TiO₂. The band gap is effectively narrowed with the smallest gap energy of 2.17 eV, and the photocatalytic activity is effectively improved due to the extended absorption range. The photocatalytic activity was evaluated by the degradation of Rhodamine B (RhB) in aqueous solution under visible light irradiation. The results show that Se doping significantly improves the photocatalytic activity of TiO₂ and 13.63 at.% Se-doped TiO₂ has the best performance.

$\text{Bi}\left({\text{Fe}}_{0.95}{\text{Co}}_{0.05}\right){\text{O}}_3$ bulk ceramics were prepared by rapid sintering using sol-gel derived fine powders. $\text{Bi}\left({\text{Fe}}_{0.95}{\text{Co}}_{0.05}\right){\text{O}}_3$ crystallized in a rhombohedrally distorted ${\text{BiFeO}}_3$ structure with compressive lattice distortion induced by the Co substitution at Fe sites from Raman study. Compared with ${\text{BiFeO}}_3$ prepared under similar conditions, the magnetic properties were significantly enhanced, with saturate magnetization of 1.6 emu/g and remnant magnetization of 0.7 emu/g at 300 K. Clear metamagnetism was observed in $\text{Bi}\left({\text{Fe}}_{0.95}{\text{Co}}_{0.05}\right){\text{O}}_3$ .

The passivation of defects at perovskite grain boundaries (GB) is crucial in achieving highly efficient and stable perovskite solar cells. Unlike the widely used additive passivation method where a mixture of additives and perovskite precursor is used for preparing perovskite films, we herein developed a new defect post-healing method via dip-coating trioctylphosphine oxide (TOPO) ligands on pre-fabricated carbon-based mesoscopic perovskite solar cells (MPSCs). Since perovskites have formed before post-healing, TOPO ligands are selectively adsorbed onto the exposed perovskite surface and hence have little influence on charge extraction of interfaces. The defects are post-healed via O atoms in PO bonds coordinated to halide-deficient sites, leading to an enhancement of the power conversion efficiency (PCE) from 11.0% to 12.8%. Moreover, due to the three hydrophobic long chain alkyls in TOPO, the humidity stability of the device has also been improved simultaneously.

Lithiated transition metal phosphates with large theoretical capacities have emerged as promising cathode materials for rechargeable lithium-ion batteries. However, the poor kinetic properties caused by their low intrinsic electronic and ionic conductivity greatly hinder their practical applications. In this work, we demonstrate a novel strategy to prepare monoclinic lithium vanadium phosphate nanoparticles implanted in carbon nanofibers as the cathodes of Li-ion cells with high capacity, flexibility, long cycle stability and significantly improved high-rate performance. The composite nanofibers were obtained by electrospinning using polyacrylonitrile and Li₃V₂(PO₄)₃ nanoparticles, followed by annealing and coating with a thin layer of carbon by plasma enhanced chemical vapor deposition. The Li₃V₂(PO₄)₃ nanocrystals with the monoclinic phase were uniformly distributed in the composite nanofibers. The electrochemical performances of the as-prepared binder-free fibrous cathodes were characterized by potentiostatic and galvanostatic tests. At the rate of 0.5 C in the range of 3.0–4.3 V, the composite displayed an initial discharge capacity of 128 mA h g⁻¹ (96.2% of the theoretical capacity). A discharge capacity of 120 mA h g⁻¹ was observed even at a high rate of 10 C, and a capacity retention of 98.9% was maintained after 500 cycles at 5 C, indicating excellent high-rate capability and capacity retention. Compared to the control samples without a carbon outer-layer, the composite nanofibers with carbon coating demonstrated much better electrochemical performances. It indicates that the carbon coating can further protect the structural integrity of nanofabric electrodes during the charge/discharge processes without hindering the Li-ion mobility and also can prevent undesired side reactions with an electrolyte, thus greatly improving the rate performance and cyclic stability of the cathode.