The development of multifunctional and durable electrocatalysts for hydrogen energy production via an energysaving avenue is urgently desired. Urea electrolysis by substituting the oxygen evolution reaction (OER) with a more oxidizable urea oxidation reaction (UOR) has been widely used to realize energysaving hydrogen production. Herein, metal−organic framework (MOF)-derived interface-engineered NiMoO 4 @NiFeP core−shell nanorods as electrocatalysts are constructed. Due to the integration of the advantages of the interface synergistic effect between the NiMoO 4 core and NiFeP shell, the as-fabricated NiMoO 4 @NiFeP electrocatalyst demonstrates remarkable electrocatalytic performance toward the hydrogen evolution reaction (HER), OER, and UOR. In the urea electrolysis system, an ultralow cell voltage of 1.30 V is needed to drive the current density of 10 mA cm −2 , which is 140 mV lower than that of the conventional overall water splitting system. The cost-efficient and high-performance NiMoO 4 @NiFeP electrocatalyst paves the way to explore practical applications of energy-saving hydrogen production.

Photocatalysis is a promising and sustainable technology in the fields of energy conversion/storage and environment purification; however, the utilization of individual component as photocatalyst is generally restricted due to the low catalytic activity deriving from the rapid recombination of photogenerated electrons/holes. Covalent organic framework (COF)‐semiconductor‐based composite photocatalysts with synergistic effects provide a feasible route to achieve high‐performance photocatalytic reactions with more active sites, strong light utilization ability, and high stability. In recent years, significant progress has been made in the rational design and preparation of the COF‐semiconductors‐based heterostructures for photocatalytic water splitting, carbon dioxide (CO2) reduction, and dye/pollutant degradation. In this Review, the synthetic strategies of COF‐semiconductor‐based heterostructures are first introduced, which includes the rational design of the morphology, connection modes, and type of heterojunctions. The performance of COF‐semiconductor‐based heterostructures in different photocatalytic reactions are comprehensively reviewed. The structure‐activity relationship and the synergistic effects within the heterostructures are discussed, and the photocatalytic mechanism and the role of COFs during the photocatalytic process are also presented. Finally, an outlook and challenges of realizing COF‐semiconductor‐based heterostructures with simple synthesis methods, diverse functions, high performance, and well‐defined reaction mechanisms are provided.