美国普林斯顿大学Bruce E. Koel团队报道了铪改性提高氧化铱析氧反应活性。相关研究成果于2021年9月1日发表在《美国化学会杂志》。

合成和使用高活性、稳定且价格合理的析氧反应电催化剂（OER）是开发高效节能且经济可行的能量转换装置（如电解槽、可充电金属空气电池和再生燃料电池）的主要挑战。目前用于OER的基准电催化剂基于氧化铱（IrOx），因为其优越的性能和优异的稳定性。然而，由于IrOx丰度低且成本高，因此大规模应用IrOx是不切实际的。

该文中，研究人员报道了一种用于OER的高活性铪改性氧化铱（IrHfxOy）电催化剂。IrHfxOy电催化剂在碱性条件下（pH=11）的活性比IrOx电催化剂高十倍，在酸性条件下（pH=1）的活性高四倍。IrHfxOy催化剂在酸性条件下的最高固有质量活性计算为6950 A gIrOx^–1，过电位（η）为0.3 V。综合利用操作数表面增强拉曼光谱（SERS）和DFT计算研究表明，对于IrOx和IrHfxOy催化剂，OER的活性位点都是Ir–O物种。Hf位的存在导致附近O位上更多的负电荷态，缩短Ir–O的键长，并降低OER中间体的自由能，从而加速OER过程。

附：英文原文

Title: Increasing Iridium Oxide Activity for the Oxygen Evolution Reaction with Hafnium Modification

Author: Fang Zhao, Bo Wen, Wenhan Niu, Zhu Chen, Chao Yan, Annabella Selloni, Christopher G. Tully, Xiaofang Yang, Bruce E. Koel

Issue&Volume: September 1, 2021

Abstract: Synthesis and implementation of highly active, stable, and affordable electrocatalysts for the oxygen evolution reaction (OER) is a major challenge in developing energy efficient and economically viable energy conversion devices such as electrolyzers, rechargeable metal-air batteries, and regenerative fuel cells. The current benchmark electrocatalyst for OER is based on iridium oxide (IrOx) due to its superior performance and excellent stability. However, large scale applications using IrOx are impractical due to its low abundance and high cost. Herein, we report a highly active hafnium-modified iridium oxide (IrHfxOy) electrocatalyst for OER. The IrHfxOy electrocatalyst demonstrated ten times higher activity in alkaline conditions (pH = 11) and four times higher activity in acid conditions (pH = 1) than a IrOx electrocatalyst. The highest intrinsic mass activity of the IrHfxOy catalyst in acid conditions was calculated as 6950 A gIrOx–1 at an overpotential (η) of 0.3 V. Combined studies utilizing operando surface enhanced Raman spectroscopy (SERS) and DFT calculations revealed that the active sites for OER are the Ir–O species for both IrOx and IrHfxOy catalysts. The presence of Hf sites leads to more negative charge states on nearby O sites, shortening of the bond lengths of Ir–O, and  lowers free energies for OER intermediates  that accelerate the OER process.

DOI: 10.1021/jacs.1c03473

Source: https://pubs.acs.org/doi/10.1021/jacs.1c03473