Li Xingkang,Luo Yifan,Daroch Maurycy,Hou Juan,Gui Weiyang
Hemicellulose and lignin act as physical barriers impeding the hydrolysis of lignocellulosic biomass by cellulases. To develop a process which could simultaneously remove most hemicellulose and lignin in biomass, in this study, oxygen-assisted ethanol organosolv pretreatment (O 2 -EOP) of sugarcane bagasse (SCB) was carried out. The effects of temperature, time, oxygen pressure and ethanol concentration on the pH of the hydrolysate, the solubilization and the chemical composition of SCB were investigated. Compared with autocatalytic EOP and acid-catalyzed EOP, O 2 -EOP could remove most xylan and lignin from SCB at much milder conditions. At optimized conditions (40/60 ethanol/water (v/v), 1.5 MPa O 2 , 160 °C and 80 min), 82.9% xylan and 83.3% lignin were removed. Glucan content in the residue reached 86.3%, much higher than results obtained by autocatalytic EOP and acid-catalyzed EOP. In subsequent enzymatic hydrolysis (1% solid loading, 4.96 mg protein/g cellulose, 72 h), O 2 -EOP pretreated SCB produced 3.97 and 1.90 times more glucose than untreated material and N 2 -EOP pretreated SCB, respectively. O 2 -EOP also produced abundant organic acids, total amounts of formic acid and acetic acid in the hemicellulose hydrolysate reached 5.42 g/L. In conclusion, O 2 -assisted EOP was an effective process for the production of pulp with high cellulose purity and good accessibility to cellulases.
Oxide-on-metal particles with exposed interfaces exhibit wealthy structures and functions, but their facile synthesis remains as a challenge. Herein we report a facile O2-assisted hydrothermal method to synthesize CeO2-on-Ag particles with different CeO2 thicknesses. In this novel approach Ag particles catalyze the O2 + H2O reaction to form surface hydroxyls that induce the preferential nucleation of Ce(OH)3 on the surfaces of Ag particles, eventually forming CeO2 adlayers on Ag particles. CeO2-on-Ag particles exhibit the CeO2 thickness-dependent SERS effect in which their best SERS effect is 2 orders stronger than that of Ag particles. They also exhibit CeO2 thickness-dependent catalytic performance in CO oxidation in which the best one is as active as traditional CeO2-supported Ag catalyst. These results open up new opportunities to synthesize oxide-on-metal particles and explore their functions by tuning the oxide adlayer thickness.
Antimony sulfide (Sb 2 S 3 ) is regarded as one of the potential candidates for the next generation of photovoltaic absorber due to its excellent photoelectric properties. However, the selection and optimization of the hole transport layer (HTL) is still a major challenge for efficiency breakthrough of the Sb 2 S 3 solar cells. In this work, lead sulfide (PbS) is deposited as a HTL of the Sb 2 S 3 device by thermal evaporation for the first time. A high quality PbS films is conformally coated on the Sb 2 S 3 rear surface by regulating the feeding amount, which thanks to the mass transfer mechanism of Ostwald ripening by scrutinizing the film growth kinetics. Meanwhile, both the valence band maximum (VBM) and Fermi levels are shifted down by a deliberate oxygen doping under a low vacuum ambient, which effectively reduces the offset between Sb 2 S 3 and carbon electrode and then accelerates hole collection. Finally, it delivers an impressive photovoltaic conversion efficiency of 6.63% for carbon-based Sb 2 S 3 solar cells, coupled with a V oc of 779 mV, J sc of 14.9 mA cm −2 and FF of 57.13%, which is 13% higher than that under high vacuum condition.
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