ZnO/black phosphorus/C3N4 composite: An effective photocatalyst for Cr (VI) reduction and degradation of rhodamine B

Sahar Moradian; Ghodsi Mohammadi Ziarani; Alireza Badiei; Siavash Iravani

doi:10.1016/j.envres.2023.117122

ZnO/black phosphorus/C₃N₄ composite: An effective photocatalyst for Cr (VI) reduction and degradation of rhodamine B

Environ Res. 2023 Dec 1;238(Pt 1):117122. doi: 10.1016/j.envres.2023.117122. Epub 2023 Sep 15.

Authors

Sahar Moradian¹, Ghodsi Mohammadi Ziarani², Alireza Badiei³, Siavash Iravani⁴

Affiliations

¹ School of Chemistry, College of Sciences, University of Tehran, Tehran, Iran.
² Department of Organic Chemistry, Faculty of Chemistry, Alzahra University, Tehran, Iran.
³ School of Chemistry, College of Sciences, University of Tehran, Tehran, Iran. Electronic address: abadiei@ut.ac.ir.
⁴ Independent Researcher, W Nazar ST, Boostan Ave, Isfahan, Iran. Electronic address: siavashira@gmail.com.

PMID: 37717806
DOI: 10.1016/j.envres.2023.117122

Abstract

The utilization of photocatalysts offers a promising approach for the removal of Cr (VI) and rhodamine dyes. Through the generation of reactive species and subsequent degradation reactions, photocatalysis provides an efficient and environmentally friendly method for the remediation of wastewater. In this study, we have synthesized an n-p-n heterojunction of carbon nitride (C₃N₄), zinc oxide (ZnO), and black phosphorus (BP) through the sonication-stirring method. The photocatalytic ability of this composite was examined for the decomposition rhodamine B (RhB) and detoxification of hexavalent chromium ion (up to 97% during 80 min) under Xenon irradiation. The results of trapper experiments indicated that the active species were hydroxyl radical (^˙OH), electron (e^-), and superoxide anion radical (^˙O₂^-). Based on the obtained potential of the lowest unoccupied molecular orbitals (LUMO) and the highest occupied molecular orbital (HOMO) for the mentioned semiconductors, through Mutt-Schottky results, the double Z-scheme mechanism was proposed for the studied process. The electrochemical impedance spectroscopy data exhibited good charge transfer for the evaluated composite versus the pure compounds. The impressive separation of holes and electrons along with the low recombination were confirmed by the responses of photocurrent and quenching the photoluminescence (pl) intensity for the composite, respectively. The current density of the composite recorded 66.6%, 87.3%, and 92% higher than those of BP, C₃N₄, and ZnO, indicating an excellent electron-hole separation for the ternary composite compared to the pure semiconductors. Diffuse reflectance spectra (DRS) data revealed 2.9, 3.17, 1.15, and 2.63 eV as the band gap values for C₃N₄, ZnO, BP, and composite. The rate constant of the new composite to remove RhB and reduce hexavalent chromium were about 4.79 and 2.64 times higher than that of C₃N₄, respectively.

Keywords: Black phosphorus; Detoxification; Heterojunction; Photocatalyst; Photodegradation.

MeSH terms

Phosphorus
Rhodamines
Superoxides
Zinc Oxide*

Substances

chromium hexavalent ion
rhodamine B
Zinc Oxide
Phosphorus
Rhodamines
Superoxides