Efficient generation of singlet oxygen(1 O_(2)) by an excitonic ene rgy transfer process is highly desired on a semiconductor photocatalyst for selective oxidation of methyl phenyl sulfide(MPS).Herein,it is demonstrat...Efficient generation of singlet oxygen(1 O_(2)) by an excitonic ene rgy transfer process is highly desired on a semiconductor photocatalyst for selective oxidation of methyl phenyl sulfide(MPS).Herein,it is demonstrated that a large amount of 1 O_(2) is produced on pristine graphitic carbon nitride(CN) nanosheet compared with bismuth oxybromide(BiOBr) and comme rcial P25 titanium dioxide(TiO_(2)).This leads to a certain photoactivity of CN for MPS oxidation.The observed ~77% selectivity for CN depends on the competitive results of excitonic energy transfer for 1 O_(2) formation and charge carrier separation for superoxide radical(O_(2)·) production,which are based on the phosphorescence spectra and electron paramagnetic resonance signals,respectively.Moreover,ultrathin CN nanosheets are synthesized by thermal treatment with the cyanuric acid-melamine hydrogen bonded aggregates as precursors.It is confirmed that the amount of produced 1 O_(2) could be increased by decreasing the thickness of resultant CN nanosheets.The optimized ultrathin CN nanosheet(~4 nm) exhibits excellent photoactivity with high selectivity(~99%).It is suggested that the excitonic energy transfer for 1 O_(2) formation is close related to the intrinsic exciton binding energy and the two-dimensional quantum confinement effect.This work establishes a basic mechanistic understanding on the excitonic processes in CN,and develops a feasible route to design CN-based photocatalysts for efficient 1 O_(2) generation.展开更多
Myocardial infarction is a devastating disease worldwide.At present,nearly 40 million patients suffer from heart failure.Owing to a lack of adequate blood supply,25%of cardiomyocytes are subjected to apoptosis and nec...Myocardial infarction is a devastating disease worldwide.At present,nearly 40 million patients suffer from heart failure.Owing to a lack of adequate blood supply,25%of cardiomyocytes are subjected to apoptosis and necrosis within a few hours after infarction.It remains challenging to find effective therapeutic methods for heart failure.On the other hand,zebrafish and neonatal mouse hearts have a strong ability to regenerate(Poss et al.,2002;Raya et al.,2003;Porrello et al.,2011),and their regeneration derives from existing cardiomyocytes(Jopling et al.,2010;Kikuchi et al..展开更多
基金NSFC(Nos.U1805255,11804086,21706044,21971057)General Financial Grant from the China Postdoctoral Science Foundation(No.2017M621316)+2 种基金the Natural Science Foundation of Heilongjiang Province,China(No.B2017006)the General Financial Grant from the Postdoctoral Science Foundation of Heilongjiang Province,China(No.LBHZ17187)the General Financial Grant from Heilongjiang Province for returned students from overseas in 2018。
文摘Efficient generation of singlet oxygen(1 O_(2)) by an excitonic ene rgy transfer process is highly desired on a semiconductor photocatalyst for selective oxidation of methyl phenyl sulfide(MPS).Herein,it is demonstrated that a large amount of 1 O_(2) is produced on pristine graphitic carbon nitride(CN) nanosheet compared with bismuth oxybromide(BiOBr) and comme rcial P25 titanium dioxide(TiO_(2)).This leads to a certain photoactivity of CN for MPS oxidation.The observed ~77% selectivity for CN depends on the competitive results of excitonic energy transfer for 1 O_(2) formation and charge carrier separation for superoxide radical(O_(2)·) production,which are based on the phosphorescence spectra and electron paramagnetic resonance signals,respectively.Moreover,ultrathin CN nanosheets are synthesized by thermal treatment with the cyanuric acid-melamine hydrogen bonded aggregates as precursors.It is confirmed that the amount of produced 1 O_(2) could be increased by decreasing the thickness of resultant CN nanosheets.The optimized ultrathin CN nanosheet(~4 nm) exhibits excellent photoactivity with high selectivity(~99%).It is suggested that the excitonic energy transfer for 1 O_(2) formation is close related to the intrinsic exciton binding energy and the two-dimensional quantum confinement effect.This work establishes a basic mechanistic understanding on the excitonic processes in CN,and develops a feasible route to design CN-based photocatalysts for efficient 1 O_(2) generation.
基金supported by grants from the National Natural Science Foundation of China(Nos.31730061,81870198 and 31821091)the National Key R&D Program of China(2018YFA080050 and 2019YFA0801602)
文摘Myocardial infarction is a devastating disease worldwide.At present,nearly 40 million patients suffer from heart failure.Owing to a lack of adequate blood supply,25%of cardiomyocytes are subjected to apoptosis and necrosis within a few hours after infarction.It remains challenging to find effective therapeutic methods for heart failure.On the other hand,zebrafish and neonatal mouse hearts have a strong ability to regenerate(Poss et al.,2002;Raya et al.,2003;Porrello et al.,2011),and their regeneration derives from existing cardiomyocytes(Jopling et al.,2010;Kikuchi et al..
