Abstract
The effective adsorption of oxygen(O2)molecules over photocatalysts is a critical step in promoting the performance of photocatalytic H2O2 production.However,g-C3N4 usually features a Yeager-type(side-on)adsorption configuration of O2 molecules,which causes the breaking of O-O bonds and severely hinders the H2O2 production activity.Herein,we synthesized an oxygen-vacancy-rich TiO2-x/g-C3N4 step-scheme(S-scheme)heterojunction to regulate the oxygen adsorption configuration and improve the 2e-ORR se-lectivity of H2O2 production.In-situ X-ray photoelectron spectroscopy(in-situ XPS)and density functional theory(DFT)calculations reveal that the S-scheme heterojunction is formed between TiO2-x and g-C3N4.The difference between their Fermi levels leads to the electron flow from g-C3N4 to TiO2-x,which in-creases the electron-deficient sites in g-C3N4.As a result,the cleavage of O-O bonds on the surface of g-C3N4 is avoided and the oxygen adsorption configuration is tuned from Yeager-type to Pauling-type(end-on).Consequently,the photocatalytic H2O2 production rate is dramatically improved to 1780.3 μmol h-1,which is about 5 times higher than that of pristine g-C3N4.This work paves a new way to tailor the oxygen adsorption configuration by rationally designing S-scheme heterojunction photocatalysts.
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