Direct Z-Scheme Cs2O-Bi2O3-ZnO Heterostructures as Efficient Sunlight-Driven Photocatalysts

Abdo Hezam; K Namratha; Deepalekshmi Ponnamma; Q A Drmosh; Adel Morshed Nagi Saeed; Chun Cheng; K Byrappa

doi:10.1021/acsomega.8b01449

Direct Z-Scheme Cs₂O-Bi₂O₃-ZnO Heterostructures as Efficient Sunlight-Driven Photocatalysts

ACS Omega. 2018 Sep 28;3(9):12260-12269. doi: 10.1021/acsomega.8b01449. eCollection 2018 Sep 30.

Authors

Abdo Hezam¹, K Namratha¹, Deepalekshmi Ponnamma², Q A Drmosh³, Adel Morshed Nagi Saeed⁴, Chun Cheng⁵, K Byrappa¹

Affiliations

¹ Center for Materials Science and Technology, University of Mysore, Vijana Bhavana, Manasagangothiri, Mysuru 570 006, India.
² Center for Advanced Materials, Qatar University, P.O. Box 2713, Doha, Qatar.
³ Physics Department and Center of Research Excellence in Nanotechnology, King Fahd University of Petroleum and Minerals, Dhahran 31261, Saudi Arabia.
⁴ Department of Polymer Science and Technology, Sri Jayachamarajendra College of Engineering, JSS Science & Technology University, Mysuru 570 006, India.
⁵ Department of Materials Science and Engineering, Southern University of Science and Technology, Shenzhen 518055, P. R. China.

Abstract

Limited light absorption, inefficient electron-hole separation, and unsuitable positions of conduction band bottom and/or valence band top are three major critical issues associated with high-efficiency photocatalytic water treatment. An attempt has been carried out here to address these issues through the synthesis of direct Z-scheme Cs₂O-Bi₂O₃-ZnO heterostructures via a facile, fast, and economic method: solution combustions synthesis. The photocatalytic performances are examined by the 4-chlorophenol degradation test under simulated sunlight irradiation. UV-vis diffuse reflectance spectroscopy analysis, electrochemical impedance test, and the observed transient photocurrent responses prove not only the significant role of Cs₂O in extending light absorption to visible and near-infrared regions but also its involvement in charge carrier separation. Radical-trapping experiments verify the direct Z-scheme approach followed by the charge carriers in heterostructured Cs₂O-Bi₂O₃-ZnO photocatalysts. The Z-scheme charge carrier pathway induced by the presence of Cs₂O has emerged as the reason behind the efficient charge carrier separation and high photocatalytic activity.