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Assembly of a Highly Active Iridium-Based Oxide Oxygen Evolution Reaction Catalyst by Using Metal-Organic Framework Self-Dissolution.
ACS Applied Materials & Interfaces ( IF 8.3 ) Pub Date : 2020-06-04 , DOI: 10.1021/acsami.0c08358 Wei Sun 1 , Xinlong Tian 2 , Jianjun Liao 1 , Hui Deng 1 , Chenglong Ma 3 , Chengjun Ge 1 , Ji Yang 3 , Weiwei Huang 1
ACS Applied Materials & Interfaces ( IF 8.3 ) Pub Date : 2020-06-04 , DOI: 10.1021/acsami.0c08358 Wei Sun 1 , Xinlong Tian 2 , Jianjun Liao 1 , Hui Deng 1 , Chenglong Ma 3 , Chengjun Ge 1 , Ji Yang 3 , Weiwei Huang 1
Affiliation
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The proton exchange membrane (PEM) electrolyzer for hydrogen production has multiple advantages but is greatly restricted by expensive iridium and sluggish oxygen evolution reaction (OER) kinetics. The most promising way to reduce the precious metal loading is to design and develop highly active Ir-based catalysts. In this study, a versatile approach is reported to prepare a hybrid in the form of a catalyst-support structure (Fe-IrOx@α-Fe2O3, abbreviated Ir@Fe-MF) by utilizing the self-dissolving properties of Fe-MIL-101 under aqueous conditions. The formation of this hybrid is mainly due to the Ir4+ and released Fe3+ ions coprecipitated to assemble into Fe-IrOx nanoparticles, and the Fe3+ released from the inward collapse of the metal–organic framework (MOF) spontaneously forms α-Fe2O3. The prepared Ir@Fe-MF-2 hybrid exhibits enhanced catalytic activity toward OER with a lower onset potential and Tafel slop, and only 260 mV overpotential is required to drive the current density to reach 10 mA cm–2. The performed characterizations clearly indicate that the IrO6 coordination structure is changed significantly by Fe incorporated into the IrO2 lattice. The performed X-ray adsorption spectra (XAS) provides evidence that Ir 5d orbital degeneracy is eliminated because of multiple orbitals being semi-occupied in the presence of Fe, which is mainly responsible for the enhancement of OER activity. These findings open an opportunity for the design and preparation of more efficient OER catalysts of transition metal oxides by utilization of the MOF materials. It should be highlighted that a long-term stability of this catalyst run at a high current density in acidic conditions still faces great challenges.
中文翻译：
金属有机骨架自溶法制备高活性铱基氧化物析氧反应催化剂
用于制氢的质子交换膜（PEM）电解器具有多个优点，但受到昂贵的铱和缓慢的氧气析出反应（OER）动力学的极大限制。减少贵金属载量的最有前途的方法是设计和开发高活性的铱基催化剂。在这项研究中，一个通用的方法报告给在催化剂支撑结构的形式制备杂交体（铁的IrO X @的α-Fe 2 ö 3，缩写为铱@的Fe-MF）利用的自溶解性质Fe-MIL-101在水性条件下。该杂化物的形成主要归因于Ir 4+和释放的Fe 3+离子共沉淀组装成Fe-IrO x纳米颗粒，和所述的Fe 3+从金属-有机构架（MOF）自发地形成的α-Fe的向内塌陷释放2 ö 3。制备的Ir @ Fe-MF-2杂化物对OER具有增强的催化活性，具有较低的起始电势和Tafel斜率，仅需260 mV的超电势即可驱动电流密度达到10 mA cm –2。进行的表征清楚地表明，通过掺入IrO 2中的铁，IrO 6的配位结构发生了显着变化格子。进行的X射线吸收光谱（XAS）提供了消除Ir 5d轨道简并性的证据，因为在Fe的存在下半轨道占据了多个轨道，这主要是OER活性的增强。这些发现为利用MOF材料设计和制备更有效的过渡金属氧化物的OER催化剂提供了机会。应该强调的是，该催化剂在酸性条件下以高电流密度运行的长期稳定性仍面临巨大挑战。
更新日期：2020-06-04
中文翻译：
金属有机骨架自溶法制备高活性铱基氧化物析氧反应催化剂
用于制氢的质子交换膜（PEM）电解器具有多个优点，但受到昂贵的铱和缓慢的氧气析出反应（OER）动力学的极大限制。减少贵金属载量的最有前途的方法是设计和开发高活性的铱基催化剂。在这项研究中，一个通用的方法报告给在催化剂支撑结构的形式制备杂交体（铁的IrO X @的α-Fe 2 ö 3，缩写为铱@的Fe-MF）利用的自溶解性质Fe-MIL-101在水性条件下。该杂化物的形成主要归因于Ir 4+和释放的Fe 3+离子共沉淀组装成Fe-IrO x纳米颗粒，和所述的Fe 3+从金属-有机构架（MOF）自发地形成的α-Fe的向内塌陷释放2 ö 3。制备的Ir @ Fe-MF-2杂化物对OER具有增强的催化活性，具有较低的起始电势和Tafel斜率，仅需260 mV的超电势即可驱动电流密度达到10 mA cm –2。进行的表征清楚地表明，通过掺入IrO 2中的铁，IrO 6的配位结构发生了显着变化格子。进行的X射线吸收光谱（XAS）提供了消除Ir 5d轨道简并性的证据，因为在Fe的存在下半轨道占据了多个轨道，这主要是OER活性的增强。这些发现为利用MOF材料设计和制备更有效的过渡金属氧化物的OER催化剂提供了机会。应该强调的是，该催化剂在酸性条件下以高电流密度运行的长期稳定性仍面临巨大挑战。
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