Luo Heng, Li Lu, Lin Fangxu, Zhang Qinghua, Wang Kai, Wang Dawei, Gu Lin, Luo Mingchuan, Lv Fan, Guo Shaojun
School of Materials Science and Engineering, Peking University, Beijing, 100871, P. R. China.
Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, P. R. China.
Adv Mater. 2024 Aug;36(32):e2403674. doi: 10.1002/adma.202403674. Epub 2024 Jun 4.
High-entropy alloys (HEAs) confine multifarious elements into the same lattice, leading to intense lattice distortion effect. The lattice distortion tends to induce local microstrain at atomic level and thus affect surface adsorptions toward different adsorbates in various electrocatalytic reactions, yet remains unexplored. Herein, this work reports a class of sub-2 nm IrRuRhMoW HEA nanoparticles (NPs) with distinct local microstrain induced by lattice distortion for boosting alkaline hydrogen oxidation (HOR) and evolution reactions (HER). This work demonstrates that the distortion-rich HEA catalysts with optimized electronic structure can downshift the d-band center and generate uncoordinated oxygen sites to enhance the surface oxophilicity. As a result, the IrRuRhMoW HEA NPs show a remarkable HOR kinetic current density of 8.09 mA µg at 50 mV versus RHE, 8.89, 22.47 times higher than those of IrRuRh NPs without internal strain and commercial Pt/C, respectively, which is the best value among all the reported non-Pt based catalysts. IrRuRhMoW HEA NPs also display great HER performances with a turnover frequency (TOF) value of 5.93 H s at 70 mV versus RHE, 4.6-fold higher than that of Pt/C catalyst, exceeding most noble metal-based catalysts. Experimental characterizations and theoretical studies collectively confirm that weakened hydrogen (H) and enhanced hydroxyl (OH) adsorption are achieved by simultaneously modulating the hydrogen adsorption binding energy and surface oxophilicity originated from intensified ligand effect and microstrain effect over IrRuRhMoW HEA NPs, which guarantees the remarkable performances toward HOR/HER.
高熵合金（HEAs）将多种元素限制在同一晶格中，导致强烈的晶格畸变效应。这种晶格畸变倾向于在原子水平上诱导局部微应变，从而影响各种电催化反应中对不同吸附质的表面吸附，但这一点尚未得到探索。在此，本文报道了一类亚2纳米的IrRuRhMoW高熵合金纳米颗粒（NPs），其具有由晶格畸变引起的独特局部微应变，用于促进碱性氢氧化反应（HOR）和析氢反应（HER）。本文表明，具有优化电子结构的富含畸变的高熵合金催化剂可以降低d带中心并产生未配位的氧位点，以增强表面亲氧性。结果，IrRuRhMoW高熵合金纳米颗粒在相对于可逆氢电极（RHE）为50 mV时显示出8.09 mA μg的显著氢氧化反应动力学电流密度，分别比无内部应变的IrRuRh纳米颗粒和商业铂碳（Pt/C）高8.89倍和22.47倍，这是所有报道的非铂基催化剂中的最佳值。IrRuRhMoW高熵合金纳米颗粒在相对于RHE为70 mV时也表现出优异的析氢反应性能，周转频率（TOF）值为5.93 H s，比Pt/C催化剂高4.6倍，超过了大多数贵金属基催化剂。实验表征和理论研究共同证实，通过同时调节IrRuRhMoW高熵合金纳米颗粒上源自增强的配体效应和微应变效应的氢吸附结合能和表面亲氧性，实现了减弱的氢（H）吸附和增强的羟基（OH）吸附，这保证了其对氢氧化反应/析氢反应的卓越性能。
