The laminated porous N-deficient g-C3N4(CN–H)is successfully synthesized by a facile two-step hydrothermal calcination method using oxalic acid-assisted melamine as the precursor.Compared with pristine g-C3N4(224μmol g-1h-1),the CN–H shows superior photocatalytic hydrogen production activity(up to 728μmol g-1h-1),which is three times higher than the unmodified counterpart.To draw out the multifaceted influences of oxalic acid modification on the visible-light-induced photocatalytic activity,various techniques are utilized to investigate the formation mechanism,structural characteristics and photoelectrical properties of CN–H.The results indicate that the addition of a trace amount of oxalic acid to the precursor melamine results in a g-C3N4 structure possessing the advantage of both nitrogen defects and laminated porosity.These properties can enlarge specific surface areas of g-C3N4,enhance an efficient separating of photogenerated electron-hole pairs and extend the range of spectral response,all contributing to the enhancement of the visible-light-induced photocatalytic activity.
Fengli YangJia RenQianqian LiuLu ZhangYuanyuan ChaiWei-Lin Dai
Rapidly deactivation of Cu/SiO2 catalysts at high liquid hour space velocity(LHSV) has been an important obstacle for scale-up application.Herein,silver modified copper phyllosilicate nanotubes were fabricated by different strategies,and implemented to the selective hydrogenation of ethylene carbonate(EC) to methanol and ethylene glycol(EG) as alternative route for the indirect utilization of CO2.The CuPs Ag-copre catalyst synthesized by the co-ammonia evaporation hydrothermal process achieved79% methanol and 99% EG yield within various ranges of EC LHSV,which was attributed to the balanced Cu+/CuO ratio and the enhanced H2 dissociation ability.Inlaid silver species over copper phyllosilicate promoted the interaction between the metal and the support,which substantially regulated the reducibility and dispersion of copper species,meanwhile,increased the stability for long-term running of the catalyst.
Huabo LiYuanyuan CuiYixin LiuLu ZhangQuan ZhangJuhua ZhangWei-Lin Dai
The morphology effect of Zr-doped CeO_2 was studied in terms of their activities in the selective oxidation of styrene to styrene oxide using tert-butyl hydroperoxide as the oxidant. In the present work, Zrdoped CeO_2 nanorods exhibited the highest catalytic performance(yield of styrene oxide and TOF value)followed by nanoparticles and nanocubes. For the Zr-doped CeO_2 nanorods, the apparent activation energy is 56.3 k J/mol, which is much lower than the values of catalysts supported on nanoparticles and nanocubes(73.3 and 93.4 k J/mol). The high resolution transmission electron microscopy results indicated that(100) and(110) crystal planes are predominantly exposed for Zr-doped CeO_2 nanorods while(100)and(111) for nanocubes,(111) for nanoparticles. The remarkably increased catalytic activity of the Zrdoped CeO_2 nanorods is mainly attributed to the higher percentage of Ce^(3+)species and more oxygen vacancies, which are associated with their exposed(100) and(110) crystal planes. Furthermore, recycling studies proved that the heterogeneous Zr-doped CeO_2 nanorods did not lose its initial high catalytic activity after five successive recycles.
