Boosting Electrochemical Oxygen Reduction Performance of Iron Phthalocyanine through Axial Coordination Sphere Interaction. Issue 3 (10th January 2022)

• Record Type: Journal Article
• Authors: Zhang, Wenlin; Meeus, Eva J.; Wang, Lei; Zhang, Lu‐Hua; Yang, Shuangcheng; de Bruin, Bas; Reek, Joost N. H.; Yu, Fengshou
• Is Part Of: ChemSusChem. Volume 15:Issue 3(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-01-10
• Subjects: carbon nanotubes -- electrocatalysis -- heterogeneous catalysis -- iron phthalocyanine -- oxygen reduction; Green chemistry -- Periodicals; Sustainable engineering -- Periodicals; Chemistry -- Periodicals; Chemical engineering -- Periodicals; 660
• DOI: 10.1002/cssc.202102379
• Languages: English
• ISSNs: 1864-5631

Abstract

Abstract: Precise regulation of the electronic states of catalytic sites through molecular engineering is highly desired to boost catalytic performance. Herein, a facile strategy was developed to synthesize efficient oxygen reduction reaction (ORR) catalysts, based on mononuclear iron phthalocyanine supported on commercially available multi‐walled carbon nanotubes that contain electron‐donating functional groups (FePc/CNT‐R, with "R" being −NH2, −OH, or −COOH). These functional groups acted as axial ligands that coordinated to the Fe site, confirmed by X‐ray photoelectron spectroscopy and synchrotron‐radiation‐based X‐ray absorption fine structure. Experimental results showed that FePc/CNT‐NH2, with the most electron‐donating −NH2 axial ligand, exhibited the highest ORR activity with a positive onset potential ( E onset =1.0 V vs. reversible hydrogen electrode) and half‐wave potential ( E 1/2 =0.92 V). This was better than the state‐of‐the‐art Pt/C catalyst ( E onset =1.00 V and E 1/2 =0.85 V) under the same conditions. Overall, the functionalized FePc/CNT‐R assemblies showed enhanced ORR performance in comparison to the non‐functionalized FePc/CNT assembly. The origin of this behavior was investigated using density functional theory calculations, which demonstrated that the coordination of electron‐donating groups to FePc facilitated the adsorption and activation of oxygen. This study not only demonstrates a series of advanced ORR electrocatalysts, but also introduces a feasible strategy for the rational design of highly active electrocatalysts for other proton‐coupled electron transfer reactions. Abstract : Interaction of the spheres : Molecular iron phthalocyanine is supported on functionalized multi‐walled carbon nanotubes through axial coordination interaction and π‐π stacking. The formed axial coordination configuration N−Fe−N4 can effectively break the planar structure of Fe−N4 and enhance the oxygen reduction performance with a half‐wave potential of E 1/2 =0.92 V, which far exceeds commercial Pt/C with 0.85 V.