A Phase and Interface Co-Engineered MoPxSy@NiFePxSy@NPS-C Hierarchical Heterostructure for Sustainable Oxygen Evolution Reaction

The construction of heterostructures with engineered phases and interfaces is crucial to essentially reform the oxygen evolution reaction (OER) in water splitting. Herein, a fine ion exchange route combined with subsequent phosphorization and sulfurization processes is developed for the controllable synthesis of a novel MoPxSy@NiFePxSy@NPS-C hierarchical heterostructure. The well-designed MoPxSy@NiFePxSy@NPS-C consists of multiple components (NiFePx, NiFeSy, and MoPxSy) anchored on N,P,S co-doped carbon, forming abundant engineered phases and interfaces, which have shown an impressive OER activity and long-term stability. The density functional theory (DFT) calculations have revealed the enhanced electronic interactions and favorable charge transfer at engineered interfaces. The introduction of N, P, and S in the engineered phases helps to tune the electronic structure of the heterostructure and promote the adsorption and desorption of the OER intermediates over the heterostructure because of the lowered energy barrier involved in the electrocatalytic OER. The new approach to multiple engineered interfaces and multiple phases may pave a way for construction of high performance heterostructure electrocatalysts.