Structural Design of Amorphous CoMoPx with Abundant Active Sites and Synergistic Catalysis Effect for Effective Water Splitting

• Published in: Advanced functional materials Vol. 30; no. 43
• Main Authors: Huang, Huawei, Cho, Ara, Kim, Seongbeen, Jun, Hyunwoo, Lee, Ahryeon, Han, Jeong Woo, Lee, Jinwoo
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc 01.10.2020
• Subjects: Amorphous structure; amorphous structures; Atomic properties; Bimetals; Catalysis; Catalysts; Catalytic activity; Electrolysis; Energy conversion; hydrogen evolution; Hydrogen evolution reactions; Mass transfer; Materials science; nanosheets; Noble metals; Phosphides; porous materials; Structural design; Water splitting
• ISSN: 1616-301X; 1616-3028
• DOI: 10.1002/adfm.202003889

Herein, a structural design principle is presented to synthesize amorphous bimetallic phosphides (a‐CoMoPx/CF) to efficiently catalyze water splitting. Porous Co‐MOF/CF and defective CoMoO4/CF are used as structure‐inducing templates to introduce rich defects and large voids that facilitate the formation of amorphous a‐CoMoPx/CF. Theoretical calculations reveal a synergistic catalytic mechanism that is based on the bimetallic components. Hierarchical nanosheet arrays combined with amorphous structures provide a superior mass transfer capacity and fully exposed atoms, increasing the electrochemical active surface area (ECSA). The structural advantages and the synergistic catalytic effect of the bimetallic components generate a‐CoMoPx/CF with excellent catalytic activity for the hydrogen evolution reaction (HER), displaying a very low overpotential of 59 mV and delivering a current density of 10 mA cm‐2 under alkaline conditions. A full electrolysis apparatus with a‐CoMoPx/CF as both cathode and anode shows a catalytic performance comparable to that of a noble metal‐based catalyst set‐up (Pt/C‐CF // RuO2‐CF), achieving 10 mA cm‐2 at a potential of 1.581 V and stable operation at 100 mA cm‐2 for more than 100 h. These findings provide a novel concept to design stable structured catalysts based on earth‐abundant elements for the large‐scale application of electrocatalysis processes related to energy conversion technologies. Amorphous bimetallic phosphide nanosheet arrays (a‐CoMoPx/CF) are synthesized using Co‐MOF‐derived defective and porous CoMoO4 as structure‐inducing templates. The amorphous a‐CoMoPx/CF with its fully exposed atoms and open structure has a much larger electrochemical active surface area than that of its crystalline counterparts and exhibits a greatly enhanced catalytic performance for water splitting; theoretical calculations demonstrate the synergistic effect of the bimetal components.