Ammonium dinitramide(ADN)is a promising oxidizer with high energy characteristic,which is a relatively new environmentally friendly oxidizer without halogens and carbon elements.However,ADN has high hygroscopicity whe...Ammonium dinitramide(ADN)is a promising oxidizer with high energy characteristic,which is a relatively new environmentally friendly oxidizer without halogens and carbon elements.However,ADN has high hygroscopicity when exposed to high humidity air,restricting its applications on the solid propellants.In this paper,a novel energetic cocrystal composed of ammonium dinitramide and 3,4-diaminofurazan(DAF)was proposed and successfully synthesized by antisolvent crystallization method,and the properties of the cocrystal were systematically investigated by analytical characterization and theoretical simulation calculations.The formation of the cocrystal was confirmed by powder X-ray diffraction,differential scanning calorimetry,scanning electron microscopy,infrared spectroscopy and Raman spectroscopy,indicating that the synthesized product was a cocrystal.Through theoretical studies,the ADN/DAF cocrystal structure was predicted,and the powder X-ray diffraction,morphology,water sorption capacity of ADN/DAF cocrystal were calculated,which was consistent with experimental phenomena.The results showed that newly prepared cocrystal of ADN/DAF had lower hygroscopicity compared to pure ADN,and the water sorption capacity was reduced from 15.35%to 7.90%.This may be due to the formation of N-H…O medium-strength hydrogen bonds between the ammonium ion of ADN and the O atom of DAF in the cocrystal,which prevents the binding of water molecules in the air and ammonium ions and reduces the probability of ADN binding to water molecules,leading to the reduction of cocrystal hygroscopicity.The newly prepared energetic cocrystal can provide theoretical and technical guidance for the study of the anti-hygroscopicity of ADN and advance the practical application of ADN.展开更多
Owing to its outstanding photoactivity,ferrioxalate is originally used as an actinometer and subsequent work has discovered that photochemistry of ferrioxalate is also fundamentally or technically important in atmosph...Owing to its outstanding photoactivity,ferrioxalate is originally used as an actinometer and subsequent work has discovered that photochemistry of ferrioxalate is also fundamentally or technically important in atmospheric chemistry and water treatment.While the overall products generated from photolysis of ferrioxalate are known to include Fe(Ⅱ),a series of oxidizing(e.g.,·OH,O_(2)^(·-)/HO_(2)^(·-))or reducing(C_(2)O_(4)^(·-)/CO_(2)^(·-))radicals and H_(2)O_(2),however,at the molecular level,the primary step of the photoreaction of ferrioxalate remains as an unsolved mystery due to the difficulty in examining such ultrafast processes.Benefiting from the development of time-resolved spectroscopy,this old question has been studied with increasing vigor recently,by means of such ever-more-sophisticated techniques(e.g.,flash photolysis,time-resolved X-ray absorption spectroscopy(XAS),femtosecond infrared(IR)absorption spectroscopy,ultrafast photoelectron spectroscopy(PES)).There are two contrary views on the primary reaction mechanism:(1)Intramolecular electron transfer(ET)precedes the cleavage of the metal-ligand bond;(2)The dissociation of C-C or Fe-O bond occurs before intramolecular ET.Thus,this review presents a comprehensive summary about the overall reaction mechanism and molecular level mechanism of ferrioxalates.In chronological order,we have elaborated two predominant but controversial views from the perspectives of different experimental approaches.Some challenges and research opportunities in this active field are also briefly discussed.展开更多
基金supported by the National Natural Science Foundation of China(22125802)Beijing Natural Science Foundation(2222017)National key research and development program(2021YFC2101202)。
文摘Ammonium dinitramide(ADN)is a promising oxidizer with high energy characteristic,which is a relatively new environmentally friendly oxidizer without halogens and carbon elements.However,ADN has high hygroscopicity when exposed to high humidity air,restricting its applications on the solid propellants.In this paper,a novel energetic cocrystal composed of ammonium dinitramide and 3,4-diaminofurazan(DAF)was proposed and successfully synthesized by antisolvent crystallization method,and the properties of the cocrystal were systematically investigated by analytical characterization and theoretical simulation calculations.The formation of the cocrystal was confirmed by powder X-ray diffraction,differential scanning calorimetry,scanning electron microscopy,infrared spectroscopy and Raman spectroscopy,indicating that the synthesized product was a cocrystal.Through theoretical studies,the ADN/DAF cocrystal structure was predicted,and the powder X-ray diffraction,morphology,water sorption capacity of ADN/DAF cocrystal were calculated,which was consistent with experimental phenomena.The results showed that newly prepared cocrystal of ADN/DAF had lower hygroscopicity compared to pure ADN,and the water sorption capacity was reduced from 15.35%to 7.90%.This may be due to the formation of N-H…O medium-strength hydrogen bonds between the ammonium ion of ADN and the O atom of DAF in the cocrystal,which prevents the binding of water molecules in the air and ammonium ions and reduces the probability of ADN binding to water molecules,leading to the reduction of cocrystal hygroscopicity.The newly prepared energetic cocrystal can provide theoretical and technical guidance for the study of the anti-hygroscopicity of ADN and advance the practical application of ADN.
基金supported by the National Natural Science Foundation of China(No.41977313)the support from the Foundation of Key Laboratory of Yangtze River Water Environment,Ministry of Education(Tongji University),China(No.YRWEF202003)Key Laboratory of Eco-geochemistry,Ministry of Natural Resources(No.ZSDHJJ202006)。
文摘Owing to its outstanding photoactivity,ferrioxalate is originally used as an actinometer and subsequent work has discovered that photochemistry of ferrioxalate is also fundamentally or technically important in atmospheric chemistry and water treatment.While the overall products generated from photolysis of ferrioxalate are known to include Fe(Ⅱ),a series of oxidizing(e.g.,·OH,O_(2)^(·-)/HO_(2)^(·-))or reducing(C_(2)O_(4)^(·-)/CO_(2)^(·-))radicals and H_(2)O_(2),however,at the molecular level,the primary step of the photoreaction of ferrioxalate remains as an unsolved mystery due to the difficulty in examining such ultrafast processes.Benefiting from the development of time-resolved spectroscopy,this old question has been studied with increasing vigor recently,by means of such ever-more-sophisticated techniques(e.g.,flash photolysis,time-resolved X-ray absorption spectroscopy(XAS),femtosecond infrared(IR)absorption spectroscopy,ultrafast photoelectron spectroscopy(PES)).There are two contrary views on the primary reaction mechanism:(1)Intramolecular electron transfer(ET)precedes the cleavage of the metal-ligand bond;(2)The dissociation of C-C or Fe-O bond occurs before intramolecular ET.Thus,this review presents a comprehensive summary about the overall reaction mechanism and molecular level mechanism of ferrioxalates.In chronological order,we have elaborated two predominant but controversial views from the perspectives of different experimental approaches.Some challenges and research opportunities in this active field are also briefly discussed.
