title: TiN nanoparticles on CNT-graphene hybrid support as noble-metal-free counter electrode for quantum-dot-sensitized solar cells.
abstract: The development of an efficient noble-metal-free counter electrode is crucial for possible applications of quantum-dot-sensitized solar cells (QDSSCs). Herein, we present TiN nanoparticles on a carbon nanotube (CNT)-graphene hybrid support as a noble-metal-free counter electrode for QDSSCs employing a polysulfide electrolyte. The resulting TiN/CNT-graphene possesses an extremely high surface roughness, a good metal-support interaction, and less aggregation relative to unsupported TiN; it also has superior solar power conversion efficiency (4.13 %) when applying a metal mask, which is much higher than that of the state-of-the-art Au electrode (3.35 %). Based on electrochemical impedance spectroscopy measurements, the enhancement is ascribed to a synergistic effect between TiN nanoparticles and the CNT-graphene hybrid, the roles of which are to provide active sites for the reduction of polysulfide ions and electron pathways to TiN nanoparticles, respectively. The combination of graphene and CNTs leads to a favorable morphology that prevents stacking of graphene or bundling of CNTs, which maximizes the contact of the support with TiN nanoparticles and improves electron-transfer capability relative to either carbon material alone.
authors.affiliation: Department of Chemical Engineering, Division of Advanced Nuclear Engineering, Pohang University of Science and Technology (POSTECH), Pohang, 790-784, Korea.
authors.forename: Duck Hyun
authors.initials: DH
authors.lastname: Youn
authors.forename: Minsu
authors.initials: M
authors.lastname: Seol
authors.forename: Jae Young
authors.initials: JY
authors.lastname: Kim
authors.forename: Ji-Wook
authors.initials: JW
authors.lastname: Jang
authors.forename: Youngwoo
authors.initials: Y
authors.lastname: Choi
authors.forename: Kijung
authors.initials: K
authors.lastname: Yong
authors.forename: Jae Sung
authors.initials: JS
authors.lastname: Lee
mesh_terms: D002384:Catalysis; D011211:Electric Power Supplies; D004563:Electrochemistry; D004566:Electrodes; D006108:Graphite / Q000737:chemistry*; D053758:Nanoparticles / Q000737:chemistry*; D037742:Nanotubes, Carbon / Q000737:chemistry*; D045663:Quantum Dots; D012993:Solar Energy; D014025:Titanium / Q000737:chemistry*
chemical_list: D037742:Nanotubes, Carbon; C041500:titanium nitride; D006108:Graphite; D014025:Titanium