Gan Meixing, Li Li, Yang Xixian, Rong Hongwei, Wang Zheng, Li Yuebin, Zhang Yuexing, Chen Xueli, Peng Xu
Collaborative Innovation Center for Advanced Organic Chemical Materials Co-constructed by the Province and Ministry, College of Chemistry & Chemical Engineering, Research Institute of Qianjiang Industry Technology, Hubei University, No. 368 Youyi Avenue, Wuhan 430062, P. R. China.
Shandong Provincial Key Laboratory of Monocrystalline Silicon Semiconductor Materials and Technology, Shandong Universities Engineering Research Center of Integrated Circuits Functional Materials and Expanded Applications, College of Chemistry and Chemical Engineering, Dezhou University, Dezhou 253023, P. R. China.
ACS Appl Mater Interfaces. 2024 Jun 5;16(22):28664-28672. doi: 10.1021/acsami.4c04688. Epub 2024 May 24.
Transition metal oxides are widely pursued as potent electrocatalysts for the oxygen evolution reaction (OER). However, single-metal chromium catalysts remain underexplored due to their intrinsic activity limitations. Herein, we successfully synthesize mixed-valence, nitrogen-doped CrO/CrO/CrN@NC nanoelectrocatalysts via one-step targeted pyrolysis techniques from a binuclear Cr-based complex (Cr(Salophen)(CHOH)), which is strategically designed as a precursor. Comprehensive pyrolysis mechanisms were thoroughly delineated by using coupled thermogravimetric analysis and mass spectrometry (TG-MS) alongside X-ray diffraction. Below 800 °C, the generation of a reducing atmosphere was noted, while continuous pyrolysis at temperatures exceeding 800 °C promoted highly oxidized CrO species with an elevated +6 oxidation state. The optimized catalyst pyrolyzed at 1000 °C (CrO/CrO/CrN@NCs-1000) demonstrated remarkable OER activity with a low overpotential of 290 mV in 1 M KOH and excellent stability. Further density functional theory (DFT) calculations revealed a much smaller reaction energy barrier of CrO than the low oxidation state species for OER reactivity. This work reveals fresh strategies for rationally engineering chromium-based electrocatalysts and overcoming intrinsic roadblocks to enable efficient OER catalysis through a deliberate oxidation state and compositional tuning.
过渡金属氧化物作为析氧反应（OER）的高效电催化剂受到广泛关注。然而，单金属铬催化剂由于其固有的活性限制，仍未得到充分研究。在此，我们通过一步靶向热解技术，从一种经过精心设计的双核铬基配合物（Cr(Salophen)(CHOH)）成功合成了混合价态、氮掺杂的CrO/CrO/CrN@NC纳米电催化剂。利用热重分析与质谱联用（TG-MS）以及X射线衍射全面地描绘了热解机理。在800℃以下，观察到还原气氛的产生，而在超过800℃的温度下持续热解则促进了具有更高+6氧化态的高度氧化的CrO物种的生成。在1000℃热解得到的优化催化剂（CrO/CrO/CrN@NCs-1000）在1 M KOH中表现出显著的OER活性，过电位低至290 mV，且具有出色的稳定性。进一步的密度泛函理论（DFT）计算表明，对于OER反应性，CrO的反应能垒比低氧化态物种小得多。这项工作揭示了合理设计铬基电催化剂以及克服固有障碍以通过有意调整氧化态和组成来实现高效OER催化的新策略。
