 The rational design and construction of bifunctional electrocatalysts through interface engineering is crucial for improving water splitting efficiency. Most tools slash NIS-2 heterostructures show enhanced electrocatalytic performance as bifunctional catalysts due to their abundant heterogeneous interfaces, which facilitate electron transfer and cooperate synergistically towards electrocatalytic reactions. This study highlights the potential of rationally constructing heterogeneous interfaces to maximize electrochemical performances for non-precious electrocatalysts in overall water splitting. This article was authored by Jing Wang Lin, Peng Cheng Wang, Hao Hen Wang, and others.