You Hanhui, Wu Dongshuang, Si Duanhui, Cao Minna, Sun Fanfei, Zhang Hao, Wang HuiMin, Liu Tian-Fu, Cao Rong
State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou 350002, P. R. China.
Division of Chemistry, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan.
J Am Chem Soc. 2022 Jun 1;144(21):9254-9263. doi: 10.1021/jacs.2c00242. Epub 2022 May 10.
Promoting the oxygen evolution reaction (OER) with saline water is highly desired to realize seawater splitting. This requires OER catalysts to resist serious corrosion and undesirable chloride oxidation. We introduce a 5d transition metal, Ir, to develop a monolayer NiIr-layered double hydroxide (NiIr-LDH) as the catalyst with enhanced OER performance for seawater splitting. The NiIr-LDH catalyst delivers 500 mA/cm at only 361 mV overpotential with ∼99% O Faradaic efficiency in alkaline seawater, which is more active than commercial IrO (763 mV, 23%) and the best known OER catalyst NiFe-LDH (530 mV, 92%). Moreover, it shows negligible activity loss at up to 650 h chronopotentiometry measurements at an industrial level (500 mA/cm), while commercial IrO and NiFe-LDH rapidly deactivated within 0.2 and 10 h, respectively. The incorporation of Ir into the Ni(OH) layer greatly altered the electron density of Ir and Ni sites, which was revealed by X-ray absorption fine structure and density functional theory (DFT) calculations. Coupling the electrochemical measurements and in situ Raman spectrum with DFT calculations, we further confirm that the generation of rate-limiting intermediate *O and *OOH species was accelerated on Ni and Ir sites, respectively, which is responsible for the high seawater splitting performance. Our results also provide an opportunity to fabricate LDH materials containing 5d metals for applications beyond seawater splitting.
利用盐水促进析氧反应（OER）对于实现海水分解至关重要。这要求OER催化剂能够抵抗严重的腐蚀和有害的氯氧化。我们引入一种5d过渡金属Ir，以开发一种单层NiIr层状双氢氧化物（NiIr-LDH）作为催化剂，用于海水分解，其OER性能得到增强。在碱性海水中，NiIr-LDH催化剂在仅361 mV的过电位下就能提供500 mA/cm²的电流，法拉第效率约为99%，其活性高于商业IrO₂（763 mV，23%）和最著名的OER催化剂NiFe-LDH（530 mV，92%）。此外，在工业级（500 mA/cm²）长达650小时的计时电位测量中，其活性损失可忽略不计，而商业IrO₂和NiFe-LDH分别在0.2小时和10小时内迅速失活。Ir掺入Ni(OH)层极大地改变了Ir和Ni位点的电子密度，这通过X射线吸收精细结构和密度泛函理论（DFT）计算得以揭示。将电化学测量、原位拉曼光谱与DFT计算相结合，我们进一步证实，限速中间体O和OOH物种的生成分别在Ni和Ir位点上加速，这是其高海水分解性能的原因。我们的结果还为制备含5d金属的LDH材料用于海水分解以外的应用提供了机会。
