Facile fabrication of atom-level heterojunction 2D MoSSe nanoplates with excellent performance in photoelectrochemistry and photocatalytic levofloxacin degradation

Abstract

Designing highly efficient photocatalysts for the degradation of overused levofloxacin (LEV) antibiotics is an important and challenging task. Herein, novel atom-level heterojunction 2D MoSSe nanoplates (MSS) with various S:Se molar ratios were obtained by hydrothermal synthesis . XRD studies indicated lattice constants of these MSS catalysts were intermediate between the values for MoS 2 and MoSe 2 , and their internal lattice distortion energy increased due to the interaction between the two types of lattice structures. Further analysis revealed the appearance of the internal electric fields in MSS catalysts, which appeared as the centers of the positive charge and the negative charge did not coincide. Due to the internal electric field, MSS catalysts had lower internal resistances, which were conducive to the transmission of internal carriers, and eventually enhanced the photoelectrochemical activity. The photocatalytic LEV degradation rate ( k ) of the MSS1 was 7.5 and 8.1 times superior to that of MoS 2 and MoSe 2 , respectively. The photocurrent densities of MSS1 and MSS4 were 3.5 and 18.2 times higher than that of MoS 2 . In addition, the conduction band position of MSS1 shifted to the higher than O 2 /•O 2 − and that of MoS 2 , which could generate •O 2 − for LEV degradation. Moreover, Electron Spin Resonance (ESR) analysis further revealed that the main active species in photocatalytic LEV degradation were photo-generated •O 2 – and •OH that generated from the transformation of the •O 2 − . Finally, a possible photocatalytic mechanism for LEV degradation was proposed. These results confirm the advantage of the developed ternary compound. • Novel atom-level heterojunction 2D MoSSe nanoplates with tunable S:Se molar ratio were obtained. • The photocatalytic and photoelectrochemical activity of the MoSSe is largely enhanced. • The photocurrent of the MoSSe photocatalyst has an enhancement of 17.26 times. • The photocatalytic activity of the MoSSe photocatalyst has an enhancement of 6.58 times.