Exploiting layered double hydroxide with modulated atomic motifs enables enhanced peroxydisulfate activation

Abstract

Exploring advanced Fenton-like catalysts with modulated local structure and grasping how the atomic motifs govern the activity and stability is a major challenge. Herein, a series of nickel–iron layered double hydroxides (NiFe-LDH) with regulated local atomic structure were presented via introducing Fe2+ to partially substitute the Ni2+-site, thereby constructing Fe-O-Fe motifs. These regulated Fe2+ containing NiFe-LDHs (Fe2+-NiFe-LDH) demonstrated enhanced catalytic performance on peroxydisulfate (PDS) activation compared with pristine NiFe-LDH. Remarkable degradation efficiency was achieved: about 92.5 % of Orange II (30 mg·L−1) could be degraded within 60 min. Meanwhile, other simulated wastewater of tetracycline, bisphenol A, and ciprofloxacin were capable of achieving efficient removal as well. Detailed characterizations elucidated that the substitution of Fe2+ resulted in the formation of Fe-O-Fe couplings, which functioned as novel motifs and accounted for the expressively promoted intrinsic catalytic performance. Simultaneously, the incorporated Fe-O-Fe motifs can improve electrochemical properties, thereby accelerating the electron transfer between catalysts and oxidants, further clarifying the exceptionally enhanced catalytic activity. Furthermore, density functional theory (DFT) calculations corroborated that Fe2+ substitution could modulate surface electronic state, give rise to strengthened binding energy, and intensify electron transfer for PDS activation. Moreover, other Fe-O-M (M represents Co, Cu, Mn) motifs were also constructed within NiFe-LDH structure, with Co exhibiting the superior catalytic performance. This work conclusively proved the significance of tailoring the local atomic structure for constructing high-efficiency catalysts, and predicted to stimulate the rational design of LDHs-based catalysts.