Gao Likun, Cui Xun, Wang Zewei, Sewell Christopher D, Li Zili, Liang Shuang, Zhang Mingyue, Li Jian, Hu Yingjie, Lin Zhiqun
School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA 30332.
Key Laboratory of Bio-based Material Science and Technology of Ministry of Education, Northeast Forestry University,150040 Harbin, China.
Proc Natl Acad Sci U S A. 2021 Feb 16;118(7). doi: 10.1073/pnas.2023421118.
The ability to develop highly active and low-cost electrocatalysts represents an important endeavor toward accelerating sluggish water-oxidation kinetics. Herein, we report the implementation and unraveling of the photothermal effect of spinel nanoparticles (NPs) on promoting dynamic active-sites generation to markedly enhance their oxygen evolution reaction (OER) activity via an integrated Raman and density functional theory (DFT) study. Specifically, NiFeO (NFO) NPs are first synthesized by capitalizing on amphiphilic star-like diblock copolymers as nanoreactors. Upon the near-infrared light irradiation, the photothermal heating of the NFO-based electrode progressively raises the temperature, accompanied by a marked decrease of overpotential. Accordingly, only an overpotential of 309 mV is required to yield a high current density of 100 mA cm, greatly lower than recently reported earth-abundant electrocatalysts. More importantly, the photothermal effect of NFO NPs facilitates surface reconstruction into high-active oxyhydroxides at lower potential (1.36 V) under OER conditions, as revealed by Raman spectroelectrochemistry. The DFT calculation corroborates that these reconstructed (Ni,Fe)oxyhydroxides are electrocatalytically active sites as the kinetics barrier is largely reduced over pure NFO without surface reconstruction. Given the diversity of materials (metal oxides, sulfides, phosphides, etc.) possessing the photo-to-thermal conversion, this effect may thus provide a unique and robust platform to boost highly active surface species in nanomaterials for a fundamental understanding of enhanced performance that may underpin future advances in electrocatalysis, photocatalysis, solar-energy conversion, and renewable-energy production.
开发高活性和低成本的电催化剂是加速缓慢的水氧化动力学的一项重要努力。在此，我们通过拉曼光谱和密度泛函理论（DFT）的综合研究，报告了尖晶石纳米颗粒（NPs）的光热效应在促进动态活性位点生成方面的实现及解析，以显著提高其析氧反应（OER）活性。具体而言，首先利用两亲性星状二嵌段共聚物作为纳米反应器合成了NiFeO（NFO）NPs。在近红外光照射下，基于NFO的电极的光热加热使温度逐渐升高，同时过电位显著降低。因此，仅需309 mV的过电位就能产生100 mA cm的高电流密度，大大低于最近报道的储量丰富的电催化剂。更重要的是，如拉曼光谱电化学所揭示的，NFO NPs的光热效应有助于在OER条件下在较低电位（1.36 V）下将表面重构为高活性羟基氧化物。DFT计算证实，这些重构的（Ni，Fe）羟基氧化物是电催化活性位点，因为与没有表面重构的纯NFO相比，动力学障碍大大降低。鉴于具有光热转换特性的材料（金属氧化物、硫化物、磷化物等）的多样性，这种效应可能因此提供一个独特而强大的平台，以促进纳米材料中高活性表面物种的生成，从而从根本上理解性能的增强，这可能为电催化、光催化、太阳能转换和可再生能源生产的未来进展奠定基础。
