Dynamic Micelle-Hydrogels for 3D-Architected Transition Metal Sulfides.

Abstract

Additive manufacturing of transition metal sulfides (TMS) enables the creation of complex 3D structures, significantly expanding their applications. However, preparing 3D-structured TMS remains challenging due to difficulties in developing suitable inks. In this study, a supramolecular micelle hydrogel as the ink to fabricate 3D-structured TMS is utilized. Initially, the hydrogels are printed and infused with metal salt solutions to stabilize the structures, which are then calcined to convert into miniaturized 3D-TMS replicas. The micellar hydrogels crosslink via hydrophobic interactions, with sodium dodecyl sulfonate (SDS) micelles providing both a hydrophobic environment and sulfur sources. During calcination, the decomposed sulfur precursors coordinate with metal ions to form various TMS, including FeS₂, Cu₂S, Ni₃S₂, and Co₉S₈, along with several metal sulfides like PbS and SnS. Additionally, the method also allows for the preparation of transition metal dichalcogenides such as MoS₂ and WS₂. The formation mechanism is demonstrated using Ni₃S₂ as an example which exhibits notable catalytic activity in oxygen evolution reactions (OER) and hydrogen evolution reactions (HER). Given its simplicity and versatility, this dynamic micellar hydrogel-derived strategy offers a promising pathway for creating advanced TMS materials.