Based on the previous research work in our laboratory, we have designed and synthesized a small-molecule, hole transport material （HTM） POZ6-2 using phenoxazine （POZ） as central unit and dicyanovinyl units as electron-withdrawing terminal groups. Through the introduction ofa 2-ethyl-hexyl bulky chain into the POZ core unit, POZ6-2 exhibits good solubility in organic solvents. In addition, POZ6-2 possesses appropriate energy levels in combination with a high hole mobility and conductivity in its pristine form. Therefore, it can readily be used as a dopant-flee HTM in perovskite solar cells （PSCs） and a conversion efficiency of 10.3% was obtained. The conductivity of the POZ6-2 layer can be markedly enhanced via doping in combination with typical additives, such as 4-tert-butylpyridine （TBP） and lithium bis（trifluoromethanesulfonyl） imide （LiTFS1）. Correspondingly, the efficiency of the PSCs was further improved to 12.3% using doping strategies. Under the same conditions, reference devices based on the well-known HTM Spiro-OMeTAD show an efficiency of 12.8%.
Ming ChengCheng ChenBo XuYong HuaFuguo ZhangLars KlooLicheng Sun
Understanding the seven coordination and O-O coupling pathway of the distinguished Ru-bda catalysts is essential for the development of next generation efficient water-oxidation catalysts based on earthabundant metals.This work reports the synthesis,characterization and catalytic properties of a monomeric ruthenium catalyst Ru-bnda(H2 bnda=2,2’-bi(nicotinic acid)-6,6’-dicarboxylic acid)featuring steric hindrance and enhanced hydrophilicity on the backbone.Combining experimental evidence with systematic density functional theory calculations on the Ru-bnda and related catalysts Ru-bda(H_(2)bda=2,2’-bipyridine-6,6’-dicarboxylic acid),Ru-pda(H_(2)pda=1,10-phenanthroline-2,9-dicarboxylic acid),and Ru-biqa(H_(2)biqa=(1,1’-biisoquinoline)-3,3’-dicarboxylic acid),we emphasized that seven coordination clearly determines presence of Ru^(Ⅴ)=O with high spin density on the ORu^(Ⅴ)=O atom,i.e.oxo with radical properties,which is one of the necessary conditions for reacting through the O-O coupling pathway.However,an additional factor to make the condition sufficient is the favorable intermolecular faceto-face interaction for the generation of the pre-reactive[Ru^(Ⅴ)=O…O=Ru^(Ⅴ)],which may be significantly influenced by the secondary coordination environments.This work provides a new understanding of the structure-activity relationship of water-oxidation catalysts and their potential to adopt I2M pathway for O-O bond formation.
Dye-sensitized photoelectrochemical cell（DS-PEC） is an especially attractive method to generate hydrogen via visible light driven water splitting. Electrolyte, an essential component of DS-PEC, plays a great role in determining the photoactivities of devices for water splitting. When using phosphate buffer（pH = 6.4）as electrolyte, the DS-PEC displayed much higher photoactivity than using 0.1 M Na;SO;（pH = 6.4） as electrolyte. The insight is phosphate anion gathers together to form a negative electrostatic field on TiO;surface, which increases the resistance in the TiO;/catalyst and electrolyte interface and validly reduces the charge recombination from TiO;to the oxidized catalyst.
Adsorption state of catalyst on photoanode is an important factor on influencing the performance of dye-sensitized photoelectrochemical cells (DS-PECs) for water splitting. Photoanode TiO2(1 + 2) was assembled with Ru(bpy)(3) phosphoric acid derivative (complex 1) as photosensitizer and complex 2 as water oxidation catalyst to compare with photoanode TiO2(1 + 3). The photocurrent density of photoanode TiO2(1 + 3) with catalyst 3 synthesized with only one end fixing on the surface of TiO2 is about four-fold of the photoanode assembled with catalyst 2 fixing with two claws on the surface of TiO2. The phenomenon should be caused by the littery arrangement and shorter distance of catalyst 2 from the active center of catalyst to TiO2 on the surface of semiconductor which led to lowly efficient electron transfer. (C) 2016 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. and Science Press. All rights reserved
A molecular [Ru(bda)]-type(bda = 2,2’-bipyridine-6,6’-dicarboxylate) water oxidation catalyst with 4-vinylpyridine as the axial ligand(Complex 1) was immobilized or co-immobilized with 1-(trifluoromethyl)-4-vinylbenzene(3 F) or styrene(St) blocking units on the surface of glassy carbon(GC) electrodes by electrochemical polymerization, in order to prepare the corresponding poly-1@GC, poly-1+P3 F@GC, and poly-1+PSt@GC functional electrodes. Kinetic measurements of the electrode surface reaction revealed that [Ru(bda)] triggers the O–O bond formation via(1) the radical coupling interaction between the two metallo-oxyl radicals(I2 M) in the homo-coupling polymer(poly-1), and(2) the water nucleophilic attack(WNA) pathway in poly-1+P3 F and poly-1+PSt copolymers. The comparison of the three electrodes revealed that the second coordination sphere of the water oxidation catalysts plays vital roles in stabilizing their reaction intermediates, tuning the O–O bond formation pathways and improving the water oxidation reaction kinetics without changing the first coordination structures.
Qiming ZhuoShaoqi ZhanLele DuanChang LiuXiujuan WuMårten S.G.AhlquistFusheng LiLicheng Sun
＜正＞Graphitic carbon nitride （g-C3N4）, a metal-free semiconductor, is a promising new class of photocatalysts f...
Jingfeng Dong1,Mei Wang1,*,Xueqiang Li1,Lin Chen1,Yu He1,Licheng Sun1,2 1State Key Laboratory of Fine Chemicals,DUT-KTH Joint Education and Research Center on Molecular Devices,Dalian University of Technology(DUT),Dalian,116012,China 2Department of Chemistry,Royal Institute of Technology(KTH),Stockholm,10044 Sweden
