Room-temperature precipitation synthesis and photocatalysis of Bi5O7I/g-C3N4 Z-scheme heterojunction

In this work, by using Bi5O7 I, KI and g-C3N4 as precursors, a novel Bi5O7 I/g-C3N4 Z-scheme heterojunction has been synthesized successfully by precipitation method at room temperature, its property of light absorption, morphologic structure, efficiency of photogenerated electron-hole were characterized. The visible-light degradation performance on Rhodamine B(RhB)by new type composite photocatalyst, the kinds of radicals and the mechanism in photocatalytic reaction system were studied. The results revealed that: The synthesis conditions of Bi5O7 I/g-C3N4 by precipitation were shown as follow:4.85g Bi(NO3)3•5H2O, 1.66g KI, 1.61g g-C3N4, 50mL glycol, 12 of reaction pH, 200r/min of reaction stirring rate and ambient reaction temperature(25℃).There's no impurity and influence on chemical structure of g-C3N4 and Bi5O7 I during the synthesis process, the recombination of Bi5O7I/g-C3N4 crystallographic plane occured on the {002} crystal plane of g-C3N4 and the {312} crystal plane of Bi5O7 I.The morphologic structure of Bi5O7 I/g-C3N4 was 3D nano petal-like, which furnished a large number of contacting site for the transfer of photogenerated electron-hole. The doping of g-C3N4 on Bi5O7 I can significantly enhance photocatalytic activity, its wavelength edge of light absorption shifted to 462nm from 425nm.The band arrangement structure of Bi5O7 I/g-C3N4 was matched with the Z-scheme heterojunction, which promoted the separation of photogenerated electron-hole, its photocurrent density (11.5mA/cm) is 2.66 and 1.47times than that of g-C3N4 (4.32mA/cm) and Bi5O7 I(7.8mA/cm) respectively. The photocatalytic degradation rate for RhB by Bi5O7I/g-C3N4 under visble light irradiation is 93.9%, which is 1.89 and 1.62times than that of Bi5O7 I and g-C3N4 respectively, the activity of photocatalytic oxidation was attributed to the intermediate radicals including •OH, •O2- and h+. © 2021, Editorial Board of China Environmental Science. All right reserved.