Zhang Baohua, Zhao Guoqiang, Zhang Bingxing, Xia Lixue, Jiang Yinzhu, Ma Tianyi, Gao Mingxia, Sun Wenping, Pan Hongge
School of Materials Science and Engineering, State Key Laboratory of Clean Energy Utilization, Zhejiang University, Hangzhou, 310027, P. R. China.
State Key Laboratory of Silicate Materials for Architectures, International School of Materials Science and Engineering, Wuhan University of Technology, Wuhan, 430070, P. R. China.
Adv Mater. 2021 Oct;33(43):e2105400. doi: 10.1002/adma.202105400. Epub 2021 Sep 21.
Electrocatalysts with high activity and long-term stability for the hydrogen oxidation reaction (HOR) under alkaline conditions is still a major challenge for anion exchange membrane fuel cells (AEMFCs). Herein, a heterostructured Ir@Pd electrocatalyst with ultrasmall Ir nanoclusters (NCs) epitaxially confined on Pd nanosheets (NSs) for catalyzing the sluggish alkaline HOR is reported. Apparent charge redistribution occurs across the heterointerface, and both experimental and theoretical results suggest that the electrons transfer from Pd to Ir, which consequently greatly weakens the hydrogen binding on Pd. More interestingly, the interfacial epitaxy results in the formation of Ir/IrO Janus nanostructures, where the partially oxidized Ir species away from the interface further optimize the hydroxyl adsorption behavior. The unique Ir@Pd heterostructure eventually shows an optimal balance between hydrogen and hydroxyl adsorption, and hence exhibits impressive HOR activity with an exchange current density of up to 7.18 mA cm in 0.1 m KOH solution. In addition, the Ir@Pd electrocatalyst exhibits negligible activity degradation owing to the confinement effect of the unique epitaxial interface.
在碱性条件下，用于氢氧化反应（HOR）的具有高活性和长期稳定性的电催化剂仍然是阴离子交换膜燃料电池（AEMFCs）面临的一项重大挑战。在此，报道了一种异质结构的Ir@Pd电催化剂，其具有超小的Ir纳米团簇（NCs）外延限制在Pd纳米片（NSs）上，用于催化缓慢的碱性HOR。明显的电荷重新分布发生在异质界面上，实验和理论结果均表明电子从Pd转移到Ir，这从而极大地削弱了氢在Pd上的吸附。更有趣的是，界面外延导致形成Ir/IrO Janus纳米结构，其中远离界面的部分氧化的Ir物种进一步优化了羟基吸附行为。独特的Ir@Pd异质结构最终在氢和羟基吸附之间表现出最佳平衡，因此在0.1 m KOH溶液中表现出令人印象深刻的HOR活性，交换电流密度高达7.18 mA cm 。此外，由于独特外延界面的限制效应，Ir@Pd电催化剂的活性降解可忽略不计。
