Hierarchical Porous Ni3S4 with Enriched High‐Valence Ni Sites as a Robust Electrocatalyst for Efficient Oxygen Evolution Reaction

• Published in: Advanced functional materials Vol. 29; no. 18
• Main Authors: Wan, Kai, Luo, Jiangshui, Zhou, Chen, Zhang, Ting, Arbiol, Jordi, Lu, Xihong, Mao, Bing‐Wei, Zhang, Xuan, Fransaer, Jan
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc 02.05.2019
• Subjects: Catalysis; Catalysts; Chemisorption; durability; Electrocatalysts; Electron transfer; Energy conversion efficiency; hierarchical porous structure; high‐valence Ni3; Materials science; Ni3S4; Organic chemistry; oxygen evolution reaction; Oxygen evolution reactions; Porosity; Reaction kinetics; Structural hierarchy; Water splitting
• ISSN: 1616-301X; 1616-3028
• DOI: 10.1002/adfm.201900315

Electrochemical water splitting is a common way to produce hydrogen gas, but the sluggish kinetics of the oxygen evolution reaction (OER) significantly limits the overall energy conversion efficiency of water splitting. In this work, a highly active and stable, meso–macro hierarchical porous Ni3S4 architecture, enriched in Ni3+ is designed as an advanced electrocatalyst for OER. The obtained Ni3S4 architectures exhibit a relatively low overpotential of 257 mV at 10 mA cm−2 and 300 mV at 50 mA cm−2. Additionally, this Ni3S4 catalyst has excellent long‐term stability (no degradation after 300 h at 50 mA cm−2). The outstanding OER performance is due to the high concentration of Ni3+ and the meso–macro hierarchical porous structure. The presence of Ni3+ enhances the chemisorption of OH−, which facilitates electron transfer to the surface during OER. The hierarchical porosity increases the number of exposed active sites, and facilitates mass transport. A water‐splitting electrolyzer using the prepared Ni3S4 as the anode catalyst and Pt/C as the cathode catalyst achieves a low cell voltage of 1.51 V at 10 mA cm−2. Therefore, this work provides a new strategy for the rational design of highly active OER electrocatalysts with high valence Ni3+ and hierarchical porous architectures. The Ni3S4 enriched with high‐valence Ni3+ enhances the chemisorption of OH−, which facilitates electron transfer from the OH− to the surface Ni sites during the oxygen evolution reaction. The hierarchical porous structure enables a high number of active sites and faster mass transfer.