Silica aerogels were prepared at ambient drying by using ethanol/trimethylchlorosilane （TMCS）/heptane solution as pore water exchange and surface modification of the wet gel before drying. The obtained silica aeroge...Silica aerogels were prepared at ambient drying by using ethanol/trimethylchlorosilane （TMCS）/heptane solution as pore water exchange and surface modification of the wet gel before drying. The obtained silica aerogels exhibit a sponge-like structure with uniform pore size distribution. The effects of heat-treatment on the hydrophobicity, specific surface area and other properties were investigated. The results indicated that the hydrophobicity of silica aerogels could be maintained up to 350℃. With increasing heating temperature, hydrophobicity decreased, and became completely hydrophilic after heat-treatment at 500℃. Brunaueremmitt-teller （BET） surface area results indicated that the specific surface area of silica aerogels increased with increasing heating temperature in the range of 150-500℃. The effects of heat-treatment on the morphology and chemical bonding state of silica aerogels were investigated by scanning electron microscopy （SEM）, differential temperature analysis （DTA） and Fourier-transform infrared spectroscopy （FT-IR）.展开更多
Xanthated crosslinked chitosan(XCCS) resin prepared under microwave irradiation were used for adsorbing Au(Ⅲ) ions in hydrochloric acid medium.The influence of pH and temperature on the adsorption capacity of XCCS wa...Xanthated crosslinked chitosan(XCCS) resin prepared under microwave irradiation were used for adsorbing Au(Ⅲ) ions in hydrochloric acid medium.The influence of pH and temperature on the adsorption capacity of XCCS was investigated.The original XCCS and the loaded XCCS were characterized by scanning electron microscope(SEM) and X-ray diffraction(XRD),respectively.The results indicate that the XCCS has ability to adsorb Au(Ⅲ) ions and the maximum adsorption capacity of Au(Ⅲ) ions on XCCS is observed at pH 1 and 20℃.The data of batch adsorption tests are fitted to kinetic models and isotherm models,respectively.The kinetics of adsorption process is found to follow pseudo-second-order kinetic rate model,and equilibrium data agree very well with the Langmuir model.Thermodynamic calculation of the Au(Ⅲ) ions adsorption process indicates that the adsorption process is spontaneous and endothermic.展开更多
Stable radicals are challenging to prepare due to their intrinsic high reactivity.Herein,three trisphenolamine radicals were readily synthesized and exhibited unexpected thermal/electrochemical stability and semicondu...Stable radicals are challenging to prepare due to their intrinsic high reactivity.Herein,three trisphenolamine radicals were readily synthesized and exhibited unexpected thermal/electrochemical stability and semiconductor property.These three nitroxide radicals could be considered as a class of aromatized nitro groups or HNO3 derivatives.The closed-shell nitro-like and open-shell nitroxide resonance structure contribute to their outstanding stability.Furthermore,the tunable ground states,extremely low band gap and p-type charge transport properties were systematically investigated.More importantly,the work presents the concept of aromatic inorganic acid radical(AIAR)and aggregation-induced radical(AIR)mechanism to understand the intrinsic structureproperty relationship of these radicals.In addition,we provide a novel strategy for the design of stable and low bandgap radicals for organic electronics,magnetics,spintronics,etc.展开更多
For the process of photovoltaic conversion in organic solar cells(OSCs)and quantum-dot solar cells(QDSCs),three of four steps are determined by exciton behavior,namely,exciton generation,exciton diffusion,and exciton ...For the process of photovoltaic conversion in organic solar cells(OSCs)and quantum-dot solar cells(QDSCs),three of four steps are determined by exciton behavior,namely,exciton generation,exciton diffusion,and exciton dissociation.Therefore,it is of great importance to regulate exciton behavior in OSCs and QDSCs for achieving high power conversion efficiency.Due to the rapid development in materials and device fabrication,great progress has been made to manage the exciton behavior to achieve prolonged exciton diffusion length and improved exciton dissociation in recent years.In this review,we first introduce the parameters that affect exciton behavior,followed by the methods to measure exciton diffusion length.Then,we provide an overview of the recent advances with regard to exciton behavior investigation in OSCs and QDSCs,including exciton lifetime,exciton diffusion coefficient,and exciton dissociation.Finally,we propose future directions in deepening the understanding of exciton behavior and boosting the performance of OSCs and QDSCs.展开更多
文摘Silica aerogels were prepared at ambient drying by using ethanol/trimethylchlorosilane （TMCS）/heptane solution as pore water exchange and surface modification of the wet gel before drying. The obtained silica aerogels exhibit a sponge-like structure with uniform pore size distribution. The effects of heat-treatment on the hydrophobicity, specific surface area and other properties were investigated. The results indicated that the hydrophobicity of silica aerogels could be maintained up to 350℃. With increasing heating temperature, hydrophobicity decreased, and became completely hydrophilic after heat-treatment at 500℃. Brunaueremmitt-teller （BET） surface area results indicated that the specific surface area of silica aerogels increased with increasing heating temperature in the range of 150-500℃. The effects of heat-treatment on the morphology and chemical bonding state of silica aerogels were investigated by scanning electron microscopy （SEM）, differential temperature analysis （DTA） and Fourier-transform infrared spectroscopy （FT-IR）.
基金financially supported by the National Natural Science Foundation of China(Nos.51004072,51004033,51074047)the National“Twelfth Five-Year”Plan for Science&Technology Support Program of China(No.2012BAE01B02)。
文摘Xanthated crosslinked chitosan(XCCS) resin prepared under microwave irradiation were used for adsorbing Au(Ⅲ) ions in hydrochloric acid medium.The influence of pH and temperature on the adsorption capacity of XCCS was investigated.The original XCCS and the loaded XCCS were characterized by scanning electron microscope(SEM) and X-ray diffraction(XRD),respectively.The results indicate that the XCCS has ability to adsorb Au(Ⅲ) ions and the maximum adsorption capacity of Au(Ⅲ) ions on XCCS is observed at pH 1 and 20℃.The data of batch adsorption tests are fitted to kinetic models and isotherm models,respectively.The kinetics of adsorption process is found to follow pseudo-second-order kinetic rate model,and equilibrium data agree very well with the Langmuir model.Thermodynamic calculation of the Au(Ⅲ) ions adsorption process indicates that the adsorption process is spontaneous and endothermic.
基金supported by the Pearl River S&T Nova Program of Guangzhou (201710010194)the National Natural Science Foundation of China (61574061, 21520102006, 21634004, 51521002, 91633301)the Foundation of Guangzhou Science and Technology Project (201707020019)
文摘Stable radicals are challenging to prepare due to their intrinsic high reactivity.Herein,three trisphenolamine radicals were readily synthesized and exhibited unexpected thermal/electrochemical stability and semiconductor property.These three nitroxide radicals could be considered as a class of aromatized nitro groups or HNO3 derivatives.The closed-shell nitro-like and open-shell nitroxide resonance structure contribute to their outstanding stability.Furthermore,the tunable ground states,extremely low band gap and p-type charge transport properties were systematically investigated.More importantly,the work presents the concept of aromatic inorganic acid radical(AIAR)and aggregation-induced radical(AIR)mechanism to understand the intrinsic structureproperty relationship of these radicals.In addition,we provide a novel strategy for the design of stable and low bandgap radicals for organic electronics,magnetics,spintronics,etc.
基金The authors thank the National Natural Science Foundation of China(Nos.52173189,22105208,61935017)Hunan Provincial Natural Science Foundation of China(No.2022JJ40570)+2 种基金the Science and Technology Development Fund,Macao SAR(No.FDCT-0044/2020/A1)UM's Research Fund(No.MYRG2020-00151-IAPME)Shenzhen Institute of Advanced Technology,and the Chinese Academy of Sciences for financial support.
文摘For the process of photovoltaic conversion in organic solar cells(OSCs)and quantum-dot solar cells(QDSCs),three of four steps are determined by exciton behavior,namely,exciton generation,exciton diffusion,and exciton dissociation.Therefore,it is of great importance to regulate exciton behavior in OSCs and QDSCs for achieving high power conversion efficiency.Due to the rapid development in materials and device fabrication,great progress has been made to manage the exciton behavior to achieve prolonged exciton diffusion length and improved exciton dissociation in recent years.In this review,we first introduce the parameters that affect exciton behavior,followed by the methods to measure exciton diffusion length.Then,we provide an overview of the recent advances with regard to exciton behavior investigation in OSCs and QDSCs,including exciton lifetime,exciton diffusion coefficient,and exciton dissociation.Finally,we propose future directions in deepening the understanding of exciton behavior and boosting the performance of OSCs and QDSCs.
