TY - JOUR AU - Wu, Ziyang AU - Liao, Ting AU - Wang, Sen AU - Mudiyanselage, Janith Adikaram AU - Micallef, Aaron S. AU - Li, Wei AU - O’Mullane, Anthony P. AU - Yang, Jianping AU - Luo, Wei AU - Ostrikov, Kostya AU - Gu, Yuantong AU - Sun, Ziqi PY - 2022/04/01 Y2 - 2024/03/29 TI - Conversion of Catalytically Inert 2D Bismuth Oxide Nanosheets for Effective Electrochemical Hydrogen Evolution Reaction Catalysis via Oxygen Vacancy Concentration Modulation JF - Nano-Micro Letters JA - Nano-Micro Lett VL - 14 IS - SE - Articles DO - 10.1007/s40820-022-00832-6 UR - https://nmlett.org/index.php/nml/article/view/1077 SP - 90 AB - <p>Oxygen vacancies (<em>V</em><sub>o</sub>) in electrocatalysts are closely correlated with the hydrogen evolution reaction (HER) activity. The role of vacancy defects and the effect of their concentration, however, yet remains unclear. Herein, Bi<sub>2</sub>O<sub>3</sub>, an unfavorable electrocatalyst for the HER due to a less than ideal hydrogen adsorption Gibbs free energy (Δ<em>G</em><sub>H*</sub>), is utilized as a perfect model to explore the function of <em>V</em><sub>o</sub> on HER performance. Through a facile plasma irradiation strategy, Bi<sub>2</sub>O<sub>3</sub> nanosheets with different <em>V</em><sub>o</sub> concentrations are fabricated to evaluate the influence of defects on the HER process. Unexpectedly, while the generated oxygen vacancies contribute to the enhanced HER performance, higher <em>V</em><sub>o</sub> concentrations beyond a saturation value result in a significant drop in HER activity. By tunning the <em>V</em><sub>o</sub> concentration in the Bi<sub>2</sub>O<sub>3</sub> nanosheets via adjusting the treatment time, the Bi<sub>2</sub>O<sub>3</sub> catalyst with an optimized oxygen vacancy concentration and detectable charge carrier concentration of 1.52 × 10<sup>24</sup>&nbsp;cm<sup>−3</sup> demonstrates enhanced HER performance with an overpotential of 174.2&nbsp;mV to reach 10&nbsp;mA&nbsp;cm<sup>−2</sup>, a Tafel slope of 80&nbsp;mV dec<sup>−1</sup>, and an exchange current density&nbsp;of 316&nbsp;mA&nbsp;cm<sup>−2</sup> in an alkaline solution, which approaches the top-tier activity among Bi-based HER electrocatalysts. Density-functional theory calculations confirm the preferred adsorption of H* onto Bi<sub>2</sub>O<sub>3</sub> as a function of oxygen chemical potential (∆<em>μ</em><sub>O</sub>) and oxygen partial potential (<em>P</em><sub>O2</sub>) and reveal that high <em>V</em><sub>o</sub> concentrations result in excessive stability of adsorbed hydrogen and hence the inferior HER activity. This study reveals the oxygen vacancy concentration-HER catalytic activity relationship and provides insights into activating catalytically inert materials into highly efficient electrocatalysts.</p><p>Highlights:</p><p>1 Catalytically inert 2D Bi<sub>2</sub>O<sub>3</sub> is activated for boosting electrochemical hydrogen evolution reaction (HER) via oxygen vacancy concentration modulation.<br>2 The relationship between the varied oxygen vacancy concentrations and the corresponding HER activity is revealed by both experimental Vo verification and theoretical density-functional theory calculations.<br>3 This work provides insights into activating catalytically inert materials into high-performance catalysts.</p> ER -