Stacking Fault‐Enriched MoNi <sub>4</sub> /MoO <sub>2</sub> Enables High‐Performance Hydrogen Evolution
Yuan Wang, Hamidreza Arandiyan, Sajjad S. Mofarah, Xiangjian Shen, Stuart A. Bartlett, Pramod Koshy, Charles C. Sorrell, Hongyu Sun, Cristina Pozo‐Gonzalo, Kamran Dastafkan, Sylvia Britto, Suresh K. Bhargava, Chuan Zhao
Abstract
Abstract Producing green hydrogen in a cost‐competitive manner via water electrolysis will make the long‐held dream of hydrogen economy a reality. Although platinum (Pt)‐based catalysts show good performance toward hydrogen evolution reaction (HER), the high cost and scarce abundance challenge their economic viability and sustainability. Here, a non‐Pt, high‐performance electrocatalyst for HER achieved by engineering high fractions of stacking fault (SF) defects for MoNi 4 /MoO 2 nanosheets (d‐MoNi) through a combined chemical and thermal reduction strategy is shown. The d‐MoNi catalyst offers ultralow overpotentials of 78 and 121 mV for HER at current densities of 500 and 1000 mA cm −2 in 1 M KOH, respectively. The defect‐rich d‐MoNi exhibits four times higher turnover frequency than the benchmark 20% Pt/C, together with its excellent durability (> 100 h), making it one of the best‐performing non‐Pt catalysts for HER. The experimental and theoretical results reveal that the abundant SFs in d‐MoNi induce a compressive strain, decreasing the proton adsorption energy and promoting the associated combination of *H into hydrogen and molecular hydrogen desorption, enhancing the HER performance. This work provides a new synthetic route to engineer defective metal and metal alloy electrocatalysts for emerging electrochemical energy conversion and storage applications.