In Situ/Operando Capturing Unusual Ir6+ Facilitating Ultrafast Electrocatalytic Water Oxidation
In Situ/Operando Capturing Unusual Ir6+ Facilitating Ultrafast Electrocatalytic Water Oxidation
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原位/操作捕获异常 Ir6 促进超快电催化水氧化
DOI：
10.1002/adfm.202104746
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发表时间：
2021-08-03
影响因子：
19
通讯作者：
Zhang, Linjuan
中科院分区：
文献类型：
--
作者：
Li, Lili;Sun, Hainan;Zhang, Linjuan
识别真正的活性位点并了解析氧反应（OER）的机制仍然是当今在可再生能源技术中开发高效电化学催化剂的一大挑战。在这里，采用原位/操作实验和理论相结合的方法，研究了Sr2CoIrO6−δ中有序OER活性Co和Ir离子的催化机理，其表现出前所未有的低过电势210 mV，达到10 mA cm-2，在钙钛矿基固态催化剂中排名最高。作为施加电压的函数的原位X射线吸收光谱表明，在OER过程中，Ir4+离子逐渐转化为极高价的Ir5+/6+，而部分Co3+离子转化为Co4+。密度泛函理论计算明确揭示了 Co-O-Ir 有序网络是超高 OER 活性的起源。这项工作通过催化剂中多活性位点的适当排列，为克服水分解 OER 动力学缓慢的瓶颈开辟了一条有希望的道路。
Identifying real active sites and understanding the mechanism of oxygen evolution reaction (OER) are still a big challenge today for developing efficient electrochemical catalysts in renewable energy technologies. Here, using a combined in situ/operando experiments and theory, the catalytic mechanism of the ordered OER active Co and Ir ions in Sr2CoIrO6−δ is studied, which exhibits an unprecedented low overpotential 210 mV to achieve 10 mA cm–2, ranking the highest performance among perovskite‐based solid‐state catalysts. Operando X‐ray absorption spectroscopies as a function of applied voltage indicates that Ir4+ ion is gradually converted into extremely high‐valence Ir5+/6+, while the part of Co3+ ion is transferred into Co4+ under OER process. Density functional theory calculations explicitly reveal the order Co‐O‐Ir network as an origin of ultrahigh OER activity. The work opens a promising path to overcome the sluggish kinetics of OER bottleneck for water splitting via proper arrangements of the multi‐active sites in catalyst.