Hu Fei, Huang Peiyu, Feng Xu, Zhou Changjian, Zeng Xinjuan, Liu Congcong, Wang Guangjin, Yang Xiaowei, Hu Huawen
School of Materials Science and Hydrogen Energy, Foshan University, Foshan, 528000, P.R. China.
Flexible Electronics Innovation Institute (FEII), Jiangxi Science and Technology Normal University, Nanchang 330013, P.R. China.
Mater Horiz. 2025 Jan 20;12(2):630-641. doi: 10.1039/d4mh01358a.
While proton exchange membrane water electrolyzers (PEMWEs) are essential for realizing practical hydrogen production, the trade-off among activity, stability, and cost of state-of-the-art iridium (Ir)-based oxygen evolution reaction (OER) electrocatalysts for PEMWE implementation is still prohibitively challenging. Ir minimization coupled with mass activity improvement of Ir-based catalysts is a promising strategy to address this challenge. Here, we present a discovery demonstrating that boron doping facilitates the one-dimensional (1D) anisotropic growth of IrO crystals, as supported by both experimental and theoretical evidence. The synthesized porous network of ultralong boron-doped iridium oxide (B-IrO) nanoneedles exhibits improved electronic conductivity and reduced charge transfer resistance, thereby increasing the number of active sites. As a result, B-IrO displays an ultrahigh OER mass activity of 3656.3 A g with an Ir loading of 0.08 mg cm, which is 4.02 and 6.18 times higher than those of the un-doped IrO nanoneedle network (L-IrO) and Adams IrO nanoparticles (A-IrO), respectively. Density functional theory (DFT) calculations reveal that the B doping moderately increases the d-band center energy level and significantly lowers the free energy barrier for the conversion of *O to *OOH, thereby improving the intrinsic activity. On the other hand, the stability of B-IrO can be synchronously promoted, primarily attributed to the B-induced strengthening of the Ir bonds, which help resist electrochemical dissolution. More importantly, when the B-IrO catalysts are applied to the membrane electrode assembly for PEM water electrolysis (PEMWE), they generate a remarkable current density of up to 2.8 A cm and maintain operation for at least 160 h at a current density of 1.0 A cm. This work provides new insights into promoting intrinsic activity and stability while minimizing the usage of noble-metal-based OER electrocatalysts for critical energy conversion and storage.
虽然质子交换膜水电解槽（PEMWEs）对于实现实际制氢至关重要，但用于PEMWE实施的最先进的铱（Ir）基析氧反应（OER）电催化剂在活性、稳定性和成本之间的权衡仍然极具挑战性。减少Ir用量并提高Ir基催化剂的质量活性是应对这一挑战的一个有前景的策略。在此，我们展示了一项发现，即硼掺杂促进了IrO晶体的一维（1D）各向异性生长，这得到了实验和理论证据的支持。合成的超长硼掺杂氧化铱（B-IrO）纳米针多孔网络表现出改善的电子导电性和降低的电荷转移电阻，从而增加了活性位点的数量。结果，B-IrO在Ir负载量为0.08 mg cm时表现出3656.3 A g的超高OER质量活性，分别比未掺杂的IrO纳米针网络（L-IrO）和亚当斯IrO纳米颗粒（A-IrO）高4.02倍和6.18倍。密度泛函理论（DFT）计算表明，硼掺杂适度提高了d带中心能级，并显著降低了O转化为OOH的自由能垒，从而提高了本征活性。另一方面，B-IrO的稳定性可以同步提高，这主要归因于硼诱导的Ir键强化，有助于抵抗电化学溶解。更重要的是，当将B-IrO催化剂应用于PEM水电解（PEMWE）的膜电极组件时，它们产生高达2.8 A cm的显著电流密度，并在1.0 A cm的电流密度下保持至少160 h的运行。这项工作为在关键能量转换和存储中促进本征活性和稳定性同时最小化贵金属基OER电催化剂的使用提供了新的见解。
