Enhanced hydrogen peroxide production performance in visible light from ultra-thin g-C3N4 nanosheets with carbon vacancies
Photocatalytic production of hydrogen peroxide(H2O2),as a green and sustainable technology,has the advantages of clean and pollution-free,safety,low energy consumption and low cost compared with the anthraquinone method commonly used in industry.Graphitic phase carbon nitride(g-C3N4),as an inorganic nonmetallic material,is a promising H2O2producing photocatalyst.However,bulk g-C3N4 suffers from severe photogenerated electrons-holes complexation and weak photogenerated charge transfer ability,resulting in its low photocatalytic H2O2 production efficiency.In order to improve the photocatalytic H2O2 production activity of g-C3N4,ultrathin g-C3N4 nanosheets containing carbon vacancies(CNS580)were prepared by simple sequential two-step high-temperature calcination in this paper,and the structure and morphology,light absorption properties and electrochemical properties of photocatalysts were characterized by XRD,SEM,AFM,ESR,UV-Vis,TPC and EIS.The results showed that the photocatalyst had an ultrathin nanosheet structure with a thickness of about 2.15nm,which could improve the transmission efficiency of photogenerated charge.Meanwhile,the introduced carbon vacancies could capture photogenerated electrons,which would improve its photogenerated electrons-holes separation ability.In the experiment of photocatalytic H2O2 production,the H2O2 production concentration by CNS580 via photocatalytic reaction for 6h could reach 0.091mmol/L,which was 4.13 times higher than that of the bulk g-C3N4.In addition,the possible mechanism of photocatalytic H2O2 production for CNS580 was discussed and proposed.
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