In-and-out of inert sites on high-entropy layered double hydroxide to facilitate peroxymonosulfate-assisted photocatalytic removal of microplastics

Abstract

Photocatalytic removal of microplastics (MPs) represents an appealing approach for simultaneously achieving MPs removal and resource recovery, while facing the challenge of developing advanced photocatalysts. Herein, this work delivers a strategy that precisely steers inert sites in-and-out from high entropy materials to optimize the activity of metal sites for efficient MPs removal. As a proof of concept, a high-entropy layered double hydroxide (LDHs) featuring high-valence Fe3+δ, Co2+ε, and Ni2+ζ metal sites is obtained by inserting and successively etching the inert Zn/Al sites, denoted as CoNiFe(VZn-Al)-LDHs. The in-and-out of Zn/Al on LDHs reduces the occupancy of the d orbital of any remaining transitional metal sites, which is favorable for promoting the scope for solar harvesting and electron-hole separation. Experimental characterization, combined with theoretical simulation, validates how transitional metal sites endow a low-energy barrier for peroxymonosulfate (PMS)-assisted photocatalysis. As a result, the CoNiFe(VZn-Al)-LDHs demonstrate excellent performance for removing various types of MPs as well as real-world plastic products. This study thus provides an atomic-scale strategy for modulating the site activity of photocatalysts and provides insights into the catalytic removal of MPs.