A critical review: 1D/2D nanostructured self-supported electrodes for electrochemical water splitting

Hydrogen economy based on electrochemical water splitting represents one of the most promising means for overcoming the rapid consumption of fossil fuels and the serious deterioration of global climate. The development of earth-abundant, efficient, and durable electrocatalysts for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) plays a vital role in the commercialization of water electrolysis. The self-supported electrode is regarded as an effective approach to developing highly active electrocatalysts with exceptional stability, compared to the conventional coated powdery-type electrocatalysts. However, lack of systematic reviews for the development of self-supported electrodes limits its innovation. The one-dimensional (1D) and two-dimensional (2D) nanostructures are substantially investigated for boosting catalytic activity due to their large surface areas, effective mass transport, and fast electron transfer. Herein, we review the state-of-the-art development of self-supported transition-metal-based electrodes with 1D/2D nanostructures for HER, OER, as well as both HER and OER, classify them as general 1D/2D nanoarrays, hierarchical 1D/2D nanostructures, and hollow 1D/2D nanostructures. This review will advance future researches and provide a guideline in developing self-supported electrodes with excellent electrocatalytic performances.