G-C ₃ 4 Nano-Photocatalyst And The Mechanism Of Its Activity Improvement

Photocatalysis is considered as a solution to crisis of environment and energ y, converting solar energy into chemical energy to be applied practically. Graphit ic carbon nitride（g-C₃N₄） with unique layers, is earth-abundant, easy-to-prepare, m etal-free and high stability, being considered as a promising candidate semicondu ctor photocatalyst. Nevertheless, the lower photocatalystic activity during to high recombination. Hence,how to enhanced separation of photoinduced electron and hole, improving photocatalytic activity of g-C₃N₄ is a significant work. Modificati on such as phosphoric sulfuric and hydrofluoric and other inorganic acids capture s the photoinduced electron on the surface has made some success. Boric acid, h owever, during to the tendency to form aggregation, is not employed widely whi le borate modification has not been reported. Thus,this work would employ boric acid and borate to modified to the surface of g-C₃N₄, to enhance the separation of the photoproducted charge carriers and promote the degrading and hydrogen production activity. The mechanism would be studied as well.Through a hydrothermal process,the boric acid modified g-C₃N₄ is prepared with a high photocatalytic activity of degrading the organic pollution. The mechanism that after the modification of boric acid on the surface, the amount of adsorbed O2 is enhanced, which could capture photoinduced electrons forming O2-, promoting the separation of photoinduced charge carrier leading the higher activity of degrading the organic pollution, is based on the measurements of SS-SPS,TPD,and I-V curves.With the presence of methyl alcohol in the system, modified g-C₃N₄ by boric acid and borate exhibit enhanced hydrogen production. Bases on the measurements of SS-SPS,TPD,and I-V curves, it is revealed that photoinduced electron is captured by positive ion effectively, in consequence reduction reaction of the captured photoinduced electron and hydrogen ion is catalyzed, subsequently activity of hydrogen production enhanced.