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In this paper, the photovoltaic performance and charge recombination of the dye-sensitized solar cells (DSCs) based on nitrogen-doped TiO 2 electrodes were investigated in detail. A negative shift of the flatband potential (V fb ) of nitrogen-doped TiO 2 film was attributed to the formation of an O-Ti-N bond, and it was indicated that the position of the edge of the V fb is shifted to negative, resulting in the improvement of the open circuit voltage for DSC with nitrogen doping. The UV-vis spectrum of the nitrogen-doped film exhibited a visible absorption in the wavelength range from 400 to 500 nm. The back electron transfer of the nitrogen-doped DSC was studied by measuring the electrochemistry impedance spectra (EIS), and the EIS for DSCs showed that the enhanced electron lifetime for nitrogen-doped TiO 2 solar cells could be attributed to the formation of O-Ti-N in the TiO 2 electrode to retard the recombination reaction at the TiO 2 photoelectrode/electrolyte interface as compared to the undoped TiO 2 solar cells. The photovoltaic performance of the DSC under high temperature conditions and one soaking in sun light for more than 1000 h indicated that the nitrogen-doped TiO 2 solar cells exhibited better stability. It indicated that the formation of O-Ti-N in the TiO 2 electrode influences the performance of the DSC. Especially, the introduction of nitrogen into the DSC can stabilize the DSC system due to the replacement of oxygen-deficient titania by nitrogen-doped TiO 2 .

Carbon nanofibers (CNFs) not only keep similar one-dimensional nanostructure, unique properties, and multi-functions to carbon nanotubes, but also exhibit a few advantages like easier production, lower cost, lower crystallinity, and...

The adsorption of glycine, glutamic acid, histidine and phenylalanine on single-layer graphdiyne/ graphene is investigated by ab initio calculations. The results show that for each amino acid molecule, the adsorption energy on graphdiyne is larger than the adsorption energy on graphene and dispersion interactions predominate in the adsorption. Molecular dynamics simulations reveal that at room temperature the amino acid molecules keep migrating and rotating on graphdiyne surface and induce fluctuation in graphdiyne bandgap. Additionally, the photon absorption spectra of graphdiyne-amino-acid systems are investigated. We uncover that the presence of amino acid molecules makes the photon absorption peaks of graphdiyne significantly depressed and shifted. Finally, quantum electronic transport properties of graphdiyne-amino-acid systems are compared with the transport properties of pure graphdiyne. We reveal that the amino acid molecules induce distinct changes in the electronic conductivity of graphdiyne. The results in this paper reveal that graphdiyne is a promising two-dimensional material for sensitively detecting amino acids and may potentially be used in biosensors.