Exfoliation of amorphous phthalocyanine conjugated polymers into ultrathin nanosheets for highly efficient oxygen reduction. Issue 7 (25th January 2019)

• Record Type: Journal Article
• Authors: Liu, Wenping; Wang, Chiming; Zhang, Lijie; Pan, Houhe; Liu, Wenbo; Chen, Jun; Yang, Dongjiang; Xiang, Yanjuan; Wang, Kang; Jiang, Jianzhuang; Yao, Xiangdong
• Is Part Of: Journal of materials chemistry. Volume 7:Issue 7(2019)
• Page Start: 3112
• Page End: 3119
• Publication Date: 2019-01-25
• Subjects: Materials -- Research -- Periodicals; Chemistry, Analytic -- Periodicals; Environmental sciences -- Research -- Periodicals; 543.0284
• DOI: 10.1039/c8ta11044a
• Languages: English
• ISSNs: 2050-7488

Abstract

Abstract : Defects and disorders in the individual layers of phthalocyanine CPs diminish interlayer π–π stacking interaction, favoring the exfoliation of the CPs into ultrathin nanosheets with a high yield. Abstract : It is a significant challenge to develop a high-efficiency synthetic methodology to access fully conjugated 2D conjugated polymer (CP)/covalent organic framework (COF) nanosheets (NSs) that have great application potential for electronics and energy. Herein, we report the exfoliation of a series of amorphous ethynyl-linked phthalocyanine (Pc) CPs (MPc-CPs, M = Fe, Co, Fe0.5 Co0.5 ) into ultrathin MPc-CP NSs. Random coupling between the four regioisomers (with D 4h, D 2h, C 2v and C s symmetry) of the two tetra-β-substituted phthalocyanine precursors endows the resulting phthalocyanine conjugated polymers MPc-CPs with intrinsic structural defects and a disordered framework on individual layers. This in turn induces a diminished interlayer overlapping and a weakened interlayer π–π stacking interaction, facilitating the possible exfoliation of MPc-CPs into ultrathin 2D NSs with a yield of over 50%. The direction observation by transmission electron microscopy (TEM) and atomic force microscopy (AFM) demonstrates that the ultrathin MPc-CP NSs possess a smooth surface with a uniform thickness of 1–3 nm and a lateral size of hundreds of nanometers. The as-prepared bimetallic Fe0.5 Co0.5 Pc-CP NSs were further used to fabricate a heterostructure Fe0.5 Co0.5 Pc-CP NS@G with graphene NSs as an oxygen reduction reaction (ORR) catalyst, which exhibits an onset potential of 1006 mV and a half-wave potential of 927 mV in 0.1 M KOH, representing one of the best values in an alkaline medium. Moreover, the excellent ORR activity of the exfoliated tetrapyrrole-based conjugated NSs hybridized with graphene has also been demonstrated by a Zn–air battery device, showing an open circuit voltage of 1.34 V and a peak power density of ca. 180 mW cm −2 .