Lignin is the world's greatest renewable aromatic biofeedstock,and it has promising applications in high value-added chemical products.Herein,N-Co/ATP-CZO was used as a catalyst for the depolymerization of alkali ...Lignin is the world's greatest renewable aromatic biofeedstock,and it has promising applications in high value-added chemical products.Herein,N-Co/ATP-CZO was used as a catalyst for the depolymerization of alkali lignin in ethanol and isopropanol systems,and explored the effects of formic acid(FA)amount,reaction time,reaction temperature and other factors on the depolymerization of alkali lignin.Among them,formic acid serves as both catalytic and in situ-hydrogen donor.Ultimately,the highest yield of bio-oil(59.28%(mass)),including 30.05%(mass)of monomer,was obtained after a reaction of FA to alkali lignin mass ratio of 4 and 240°C for 8 h.Among the monomers,the yield of Guaiacol was the highest(5.94%(mass)),followed by 2-methoxy-4-methylphenol(5.74%(mass)).This study,the modification of attapulgite was carried out to reduce the acidity while enhancing the catalytic activity for depolymerization,and the selection of hydrogen donor was investigated.A feasible pathway for lignin depolymerization research was opened.展开更多
Solar-blind ultraviolet photodetectors with metal-semiconductor-metal structure were fabricated based onβ-(Al_(0.25)Ga_(0.75))_(2)O_(3)/β-Ga_(2)O_(3) film grown by metal-organic chemical vapor deposition.It was know...Solar-blind ultraviolet photodetectors with metal-semiconductor-metal structure were fabricated based onβ-(Al_(0.25)Ga_(0.75))_(2)O_(3)/β-Ga_(2)O_(3) film grown by metal-organic chemical vapor deposition.It was known that various surface states increase dark current and a large number of defects can hinder the transport of carriers,resulting in low switching ratio and low responsivity of the device.In this work,β-(Al_(0.25)Ga_(0.75))_(2)O_(3) films are used as surface passivation materials.Owning to its wide band gap,we obtain excellent light transmission and high lattice matching withβ-Ga_(2)O_(3).We explore the change and mechanism of the detection performance of theβ-Ga_(2)O_(3) detector afterβ-(Al_(0.25)Ga_(0.75))_(2)O_(3) surface passivation.It is found that under the illumination with 254 nm light at bias 5 V,theβ-(Al_(0.25)Ga_(0.75))_(2)O_(3)/β-Ga_(2)O_(3)photodetectors show dark current of just 18 pA and high current on/off ratio of 2.16×10^(5).The dark current is sharply reduced about 50 times after passivation of theβ-Ga_(2)O_(3) surface,and current on/off ratio increases by approximately 2 times.It is obvious thatβ-Ga_(2)O_(3) detectors withβ-(Al_(0.25)Ga_(0.75))_(2)O_(3) surface passivation can offer superior detector performance.展开更多
基金financially supported by National Natural Science Foundation of China (21774059)。
文摘Lignin is the world's greatest renewable aromatic biofeedstock,and it has promising applications in high value-added chemical products.Herein,N-Co/ATP-CZO was used as a catalyst for the depolymerization of alkali lignin in ethanol and isopropanol systems,and explored the effects of formic acid(FA)amount,reaction time,reaction temperature and other factors on the depolymerization of alkali lignin.Among them,formic acid serves as both catalytic and in situ-hydrogen donor.Ultimately,the highest yield of bio-oil(59.28%(mass)),including 30.05%(mass)of monomer,was obtained after a reaction of FA to alkali lignin mass ratio of 4 and 240°C for 8 h.Among the monomers,the yield of Guaiacol was the highest(5.94%(mass)),followed by 2-methoxy-4-methylphenol(5.74%(mass)).This study,the modification of attapulgite was carried out to reduce the acidity while enhancing the catalytic activity for depolymerization,and the selection of hydrogen donor was investigated.A feasible pathway for lignin depolymerization research was opened.
基金Project supported by China Postdoctoral Science Foundation (Grant No.042600055)Research on Frontiers of Materials Science,Beijing Municipal Science and Technology Commission (Grant No.Z181100004418006)。
文摘Solar-blind ultraviolet photodetectors with metal-semiconductor-metal structure were fabricated based onβ-(Al_(0.25)Ga_(0.75))_(2)O_(3)/β-Ga_(2)O_(3) film grown by metal-organic chemical vapor deposition.It was known that various surface states increase dark current and a large number of defects can hinder the transport of carriers,resulting in low switching ratio and low responsivity of the device.In this work,β-(Al_(0.25)Ga_(0.75))_(2)O_(3) films are used as surface passivation materials.Owning to its wide band gap,we obtain excellent light transmission and high lattice matching withβ-Ga_(2)O_(3).We explore the change and mechanism of the detection performance of theβ-Ga_(2)O_(3) detector afterβ-(Al_(0.25)Ga_(0.75))_(2)O_(3) surface passivation.It is found that under the illumination with 254 nm light at bias 5 V,theβ-(Al_(0.25)Ga_(0.75))_(2)O_(3)/β-Ga_(2)O_(3)photodetectors show dark current of just 18 pA and high current on/off ratio of 2.16×10^(5).The dark current is sharply reduced about 50 times after passivation of theβ-Ga_(2)O_(3) surface,and current on/off ratio increases by approximately 2 times.It is obvious thatβ-Ga_(2)O_(3) detectors withβ-(Al_(0.25)Ga_(0.75))_(2)O_(3) surface passivation can offer superior detector performance.
