Recent Progress on the Ultralow‐Overpotential Electrocatalysts for Hydrogen Evolution Reaction

ABSTRACT Electrocatalytic water splitting is crucial for sustainable clean hydrogen production through the cathodic hydrogen evolution reaction (HER). The development of efficient electrocatalysts with ultralow overpotentials is recognized as a key to the practical deployment of water electrolysis. This review outlines HER electrocatalysis fundamentals, including the reaction pathways and the performance evaluation metrics, and summarizes the recent progress of ultralow overpotential HER catalysts. For reducing the HER overpotential, a range of sophisticated strategies have been proposed for the noble or transition metal‐based catalytic systems, such as alloying, doping, interface, phase, and defect engineering. Emerging carbon‐supported single‐atom catalysts have also been introduced for the HER electrocatalysis. Moreover, critical challenges are discussed on the HER electrocatalysts, including poor industrial durability, limited scalable synthesis, and cost‐activity trade‐offs. Last but not least, future prospects have been outlooked for the HER catalyst innovations, such as machine learning for catalyst discovery, multi‐scale structural protocols of porous architectures, and so on. This review aims to provide a comprehensive reference for the community to promote the industrialization of water electrolysis technology and the green hydrogen economy.