Abstract: Water electrolysis is a sustainable approach for hydrogen production by using electricity from clean energy sources. However, both the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) associated with water electrolysis are kinetically sluggish, leading to low efficiency in corresponding electrolysis devices. In addition, current electrocatalysts that can catalyze both HER and OER to practical rates require noble metals such as platinum that are low in abundance and high in price, severely limiting commercialization. As a result, the development of high-performance and cost-effective non-noble metal electrocatalysts to replace noble ones has intensified. Based on this, this review will comprehensively present recent research in the design, synthesis, characterization and performance validation/optimization of non-noble metal HER electrocatalysts and analyze corresponding catalytic mechanisms. Moreover, several important types of non-noble metal electrocatalysts including zero-dimensional, one-dimensional, two-dimensional and three-dimensional materials are presented with an emphasis on morphology/structure, synergetic interaction between metal and support, catalytic property and HER activity/stability. Furthermore, existing technical challenges are summarized and corresponding research directions are proposed toward practical application.Water electrolysis is a sustainable approach for hydrogen production by using electricity from clean energy sources. However, both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) are kinetically sluggish, causing low efficiency of the electrolysis devices. The currently used noble metals, such as Pt-based electrocatalysts for catalyzing both HER and OER to practical rates, have low abundances and high price, limiting their commercialization. In this regard, developing high-performance and cost-effective non-noble metal electrocatalysts to replace noble ones has become a hot research topic.

Key words: Water electrolysis, Non-noble metal, Electrocatalysts, Hydrogen evolution reaction, Multidimensional material