Micro-pyrolysis perturbation promotes electrocatalytic activity of tetranuclear nickel clusters

• Published in: Electrochimica acta 2023-10, Vol.464, p.142794, Article 142794
• Main Authors: Wang, Lu, Li, Li, Gan, Meixing, Wang, Zheng, Li, Tian, Wang, Zhao, Li, Yuebin, Tao, Shi, Peng, Xu
• Format: Article
• Language: English
• Subjects: Amorphous phase; Bifunctional electrocatalysts; Micro-pyrolysis; Tetranuclear nickel clusters
• ISSN: 0013-4686; 1873-3859
• DOI: 10.1016/j.electacta.2023.142794

•A Judicious Design of Nickel Precursor for OER/UOR.•Micro-pyrolysis perturbation strategy. We propose a new route for the preparation of high-performance bifunctional electrocatalysts by micro-pyrolysis perturbation from coordination molecular clusters.•Ni4-350 achieved the over-potential of 247 mV in 10 mA·cm−2 in 1 M KOH solution and the corresponding potential of 1.366 V in the solution of 1 M KOH + 0.33 M Urea. It also has good OER/UOR bifunctional electrochemical activity at long-term stability within 10 h. As for the preparation of efficient and stable electrocatalysts containing transition metal heteroatoms by high-temperature pyrolysis is intriguing. However, studies on the pyrolysis of complexes in low-temperature range to obtain efficient catalytic transport platforms are rare. Herein, we propose a micro-pyrolysis perturbation strategy in constructing nickel molecular cluster-based bifunctional electrocatalysts, derived from a case of the tetranuclear Schiff-based nickel molecular cluster Ni4 (Ni4(II)C46H68N4O18) with N, O coordination mode. The crystal structure undergoes mild decomposition of peripheral ligands during the pyrolysis process are revealed by in situ Thermogravimetry-mass spectrometry (TG-MS) and ex-situ synchrotron-based X-ray absorption spectroscopy (XAS) technology. Besides, nickel molecular clusters transform into amorphous materials with metal-centered active Ni-O exposed on the surface under micro-pyrolysis perturbation providing additional active sites. The bifunctional catalyst Ni4-350 displays a low overpotential of 247 mV for the OER, and 1.366 V for the UOR at 10 mA·cm−2, which is also stable in the alkaline medium for 10 h of continuous running. This model study highlights that the micro-pyrolysis perturbation strategy can provide stable highly active centres while retaining the host structural framework in Ni-based clusters with promising potential application in low-potential OER/UOR electrocatalysts. The intrinsic mechanism of tetranuclear nickel cluster decomposition in nitrogen atmosphere and the reason why the highly active µ2-O bridge is exposed on the surface to generate new active sites are studied through the micro thermal decomposition perturbation strategy. Ni4-350 exhibited good OER and UOR electrocatalytic activity at the current density of 10 mA·cm−2. [Display omitted]