Highly efficient and robust electrocatalysts have been in urgent demand for oxygen evolution reaction(OER).For this purpose,high-cost carbon materials,such as graphene and carbon nanotubes,have been used as supports t...Highly efficient and robust electrocatalysts have been in urgent demand for oxygen evolution reaction(OER).For this purpose,high-cost carbon materials,such as graphene and carbon nanotubes,have been used as supports to metal oxides to enhance their catalytic activity.We report here a new Co_(3)O_(4)-based catalyst with nitrogen-doped porous carbon material as the support,prepared by pyrolysis of porous polyurea(PU) with Co(NO_(3))_(2)immobilized on its surface.To this end,PU was first synthesized,without any additive,through a very simple one-step precipitation polymerization of toluene diisocyanate in a binary mixture of H2O-acetone at room temperature.By immersing PU in an aqueous solution of Co(NO_(3))_(2)at room temperature,a cobalt coordinated polymer composite,Co(NO_(3))_(2)/PU,was obtained,which was heated at 500℃ in air for 2 h to get a hybrid,Co_(3)O_(4)/NC,consisting of Co_(3)O_(4)nanocrystals and sp2-hybridized N-doped carbon.Using this Co_(3)O_(4)/NC as a catalyst in OER,a current density of10 mA·cm^(-2)was readily achieved with a low overpotential of 293 mV with a Tafel slope of87 mV·dec^(-1),a high catalytic activity.This high performance was well retained after 1000 recycled uses,demonstrating its good durability.This work provides therefore a facile yet simple pathway to fabrication of a new transition metal oxides-based N-doped carbon catalyst for OER with high performance.展开更多
Conventional fluorescent polymers are featured by large conjugation structures.In contrast,a new class of fluorescent polymers without any conjugations is gaining great interest in immerging applications.Polyamide is ...Conventional fluorescent polymers are featured by large conjugation structures.In contrast,a new class of fluorescent polymers without any conjugations is gaining great interest in immerging applications.Polyamide is a typical member of the conjugation-free fluorescent polymers.However,studies on their electrophotonic property are hardly available,although widely used in many fields.Herein,poly(ethylene succinamide),PA24,is synthesized;its chemical structure confirmed through multiple techniques(NMR,FTIR,XRD,etc.).PA24 is highly emissive as solid and in its solution at room temperature,and the emission is excitation and concentration dependant,with an unusual blue shift under excitation from 270 nm to 320 nm,a hardly observed phenomenon for all fluorescent polymers.Quite similar emission behavior is also observed under cryogenic condition at 77 K.Its emission behavior is thoroughly studied;the ephemeral emission blue-shift is interpreted through Förster resonance energy transfer.Based on its structures,the emission mechanism is ascribed to cluster-triggered emission,elucidated from multianalyses(NMR,FTIR,UV absorbance and DLS).In presence of a dozen of competitive metal ions,PA24 emission at 450 nm is selectively quenched by Fe^(3+).PA24 is used as probe for Fe^(3+)and H_(2)O_(2) detections and in data encryption.Therefore,this work provides a novel face of polyamide with great potential applications as sensors in different fields.展开更多
基金financially supported by the Natural Science Foundation of Shandong Province,China(grant numbers ZR2021MB112,ZR2019MB031,ZR2020QB065)Natural Science Foundation of Guangdong Province,China(grant number2020A1515110374)Science and Technology Bureau of Jinan City,Shandong Province,China(2021GXRC105)。
文摘Highly efficient and robust electrocatalysts have been in urgent demand for oxygen evolution reaction(OER).For this purpose,high-cost carbon materials,such as graphene and carbon nanotubes,have been used as supports to metal oxides to enhance their catalytic activity.We report here a new Co_(3)O_(4)-based catalyst with nitrogen-doped porous carbon material as the support,prepared by pyrolysis of porous polyurea(PU) with Co(NO_(3))_(2)immobilized on its surface.To this end,PU was first synthesized,without any additive,through a very simple one-step precipitation polymerization of toluene diisocyanate in a binary mixture of H2O-acetone at room temperature.By immersing PU in an aqueous solution of Co(NO_(3))_(2)at room temperature,a cobalt coordinated polymer composite,Co(NO_(3))_(2)/PU,was obtained,which was heated at 500℃ in air for 2 h to get a hybrid,Co_(3)O_(4)/NC,consisting of Co_(3)O_(4)nanocrystals and sp2-hybridized N-doped carbon.Using this Co_(3)O_(4)/NC as a catalyst in OER,a current density of10 mA·cm^(-2)was readily achieved with a low overpotential of 293 mV with a Tafel slope of87 mV·dec^(-1),a high catalytic activity.This high performance was well retained after 1000 recycled uses,demonstrating its good durability.This work provides therefore a facile yet simple pathway to fabrication of a new transition metal oxides-based N-doped carbon catalyst for OER with high performance.
基金Natural Science Foundation of Shandong Province(Nos.ZR2019MB031 and ZR2021MB112)Science and Technology Bureau of Jinan city(No.2021GXRC105),Shandong Province,China.
文摘Conventional fluorescent polymers are featured by large conjugation structures.In contrast,a new class of fluorescent polymers without any conjugations is gaining great interest in immerging applications.Polyamide is a typical member of the conjugation-free fluorescent polymers.However,studies on their electrophotonic property are hardly available,although widely used in many fields.Herein,poly(ethylene succinamide),PA24,is synthesized;its chemical structure confirmed through multiple techniques(NMR,FTIR,XRD,etc.).PA24 is highly emissive as solid and in its solution at room temperature,and the emission is excitation and concentration dependant,with an unusual blue shift under excitation from 270 nm to 320 nm,a hardly observed phenomenon for all fluorescent polymers.Quite similar emission behavior is also observed under cryogenic condition at 77 K.Its emission behavior is thoroughly studied;the ephemeral emission blue-shift is interpreted through Förster resonance energy transfer.Based on its structures,the emission mechanism is ascribed to cluster-triggered emission,elucidated from multianalyses(NMR,FTIR,UV absorbance and DLS).In presence of a dozen of competitive metal ions,PA24 emission at 450 nm is selectively quenched by Fe^(3+).PA24 is used as probe for Fe^(3+)and H_(2)O_(2) detections and in data encryption.Therefore,this work provides a novel face of polyamide with great potential applications as sensors in different fields.
