Rhakho Novuhulu, Patil Sayali Ashok, Austeria P Muthu, Nagaraj Monika, Saxena Manav, Jadhav Arvind H, Samal Akshaya K
Centre for Nano and Material Sciences, Jain University, Jain Global Campus, Ramanagara, Bangalore 562112, Karnataka, India.
ACS Appl Mater Interfaces. 2025 Jun 18;17(24):35505-35521. doi: 10.1021/acsami.5c05517. Epub 2025 Jun 3.
Metal oxides are among the most promising electrocatalysts for the oxygen evolution reaction (OER). However, metal oxides often exhibit poor conductivity and electron transfer, limiting efficient charge transfer. Tuning the population of the d-orbital near the Fermi level and inducing porosity at the electrode-electrolyte interface can alter the charge transfer kinetics. This can also be achieved via doping with a conductive metal such as nickel (Ni) as it effectively tunes the electronic conductivity of lanthanum (La) coordinated complex and offers lattice stability by lowering the formation energy of LaO(CO). However, the precise addition of dopants for tuning the interfacial charge transfer properties and structural transformation of nanomaterials is poorly understood. Understanding and optimizing the surface and intrinsic properties are two integral parameters for developing an efficient electrocatalyst. Therefore, this work focuses on tuning and stabilizing the structure by lowering the lattice formation energy. Thick and broad petals developed at lower doping transformed into thin and sharp petals upon increasing the number of dopants. This transformation indicates that the optimal concentration facilitates greater electron redistribution and increased active site density. In addition, the transformation of smooth surface petals of NiLaOHCO to porous surface NiLaO(CO) microflowers by calcination exhibits superior OER activity, exhibiting an overpotential of 309 mV at a current density of 10 mA cm in alkaline conditions. This enhanced activity is attributed to enhanced ion diffusion and charge transfer kinetics. This work establishes a clear correlation between doping and the optimum molar concentration of Ni content for a stable lattice structure of La. Additionally, it explores the design and structural construction of electrocatalysts by doping and calcination processes to provide insights into the structural and chemical aspects that drive the OER efficiency.
金属氧化物是析氧反应（OER）最具前景的电催化剂之一。然而，金属氧化物通常表现出较差的导电性和电子转移能力，限制了有效的电荷转移。调节费米能级附近的d轨道数量并在电极 - 电解质界面诱导孔隙率可以改变电荷转移动力学。这也可以通过掺杂导电金属如镍（Ni）来实现，因为它有效地调节了镧（La）配位络合物的电子导电性，并通过降低LaO(CO)的形成能提供晶格稳定性。然而，对于精确添加掺杂剂以调节纳米材料的界面电荷转移特性和结构转变的理解却很少。理解和优化表面及本征性质是开发高效电催化剂的两个不可或缺的参数。因此，这项工作专注于通过降低晶格形成能来调节和稳定结构。在较低掺杂量下形成的厚而宽的花瓣在增加掺杂剂数量后转变为薄而尖的花瓣。这种转变表明最佳浓度有利于更大程度的电子重新分布和增加活性位点密度。此外，通过煅烧将NiLaOHCO的光滑表面花瓣转变为多孔表面的NiLaO(CO)微花表现出优异的OER活性，在碱性条件下，在电流密度为10 mA cm时过电位为309 mV。这种增强的活性归因于增强的离子扩散和电荷转移动力学。这项工作建立了掺杂与La稳定晶格结构的最佳镍含量摩尔浓度之间的明确关联。此外，它还通过掺杂和煅烧过程探索了电催化剂的设计和结构构建，以深入了解驱动OER效率的结构和化学方面。
