ABSTRACT
Photocatalysis of dye degradation is one of green and cheap technologies for solving environmental pollution. Whereas it is rarely concerned that the degradation process varied with the change of solution condition, this work studied the influence of hydrion in the solution on the photodegradation process of Rhodamine B (RhB) over g-C3N4. The photocatalytic activity of RhB degradation was enhanced gradually with increased hydrion content in the system. The efficiency for RhB degradation over g-C3N4 in weak acidic system with interference of multiple metal-ions still reached near 95% after 30 min of natural sunlight irradiation. A large amount of oxidation species and the hydroxylation mineralization process were induced by increasing the hydrion concentration. Two degradation processes for deethylation of four ethyl groups and the direct chromophoric degradation were discovered and proved by multifarious intermediates in different systems using the ESR technique, LC/MS and GC/MS analysis. In addition, the photosensitization played a critical role in the RhB degradation. A feasible degradation mechanism was proposed for the RhB degradation based on the experimental results.
ABSTRACT
Hematite-cuprous oxide (α-Fe2O3/Cu2O) nanocomposites are synthesized based on the design of Z-scheme photocatalyst for CO2 reduction. The band structure for the typical Fe2O3/Cu2O (with 1:1 mole ratio) is characterized by UV-vis reflectance spectroscopy and X-ray/ultraviolet photoelectron spectroscopy, and its heterojunction is determined to be Type II band alignment. The photoreduction CO2 activities of the heterostructures are investigated in the presence of water vapor. The CO yields are changed with Fe/Cu mole ratio, and the maximal CO yield attains 5.0 µmol·g cat(-1) after 3 h of visible-light irradiation. Besides the effect of light wavelength, H2O/CO2 molar ratio and temperature on the products is studied. The selectivity of the prepared catalysts is tunable by modulating the light wavelength. The reaction mechanism is proposed and further confirmed experimentally. The results gained herein may provide some insights into the design of Z-scheme photocatalysts for CO2 reduction.
