Interfacial peroxidase-like catalytic activity of surface-immobilized cobalt phthalocyanine on multiwall carbon nanotubes

Abstract

The rapid diffusional mass transfer process (DMTP) always results in a highly efficient reaction. Herein, cobalt phthalocyanine (CoPc) was covalently anchored on to multiwall carbon nanotubes (MWCNTs) by an easy and moderate one-step deamination method to obtain the catalyst MWCNT-immobilized CoPc (CoPc-MWCNT). The interfacial peroxidase-like catalytic activity of CoPc-MWCNTs is described for controllable H 2 O 2 activation. According to the experimental results and density functional theory calculations, we can be confident that high-valent cobalt-oxo intermediates are formed during the H 2 O 2 activation. Such active species are anchored and exposed on the surface of MWCNTs, shortening the DMTP and enhancing the resistance of CoPc-MWCNTs to oxidative decay. The introduction of linear alkylbenzene sulphonates (LAS) facilitates the catalytic H 2 O 2 activation by CoPc-MWCNTs, and at the same time, CoPc-MWCNTs could maintain a high and sustained catalytic activity because of the specific hydrophobic interactions between the long-chain alkyl group of LAS and the p-conjugated surface of the MWCNTs. † Electronic supplementary information (ESI) available: The XPS Co1s data, UV-vis spectra, raman spectra, dynamic thermogravimetric analytical results, the EPR spectra, the calculated bond lengths for the energy minimized DFT models and the catalytic performance of CoPc-MWCNTs under other different conditions. See www.rsc.org/advances 9374 | RSC Adv., 2015, 5, 9374-9380 This journal is

CO2 electrochemical catalytic reduction with a highly active cobalt phthalocyanine

“…All these spectra present the typical features expected for a cobalt (II) phthalocyanine complex, i.e., a low intensity pre-edge peak at 7711 eV (corresponding to a 1s to 3d/4p transition) and a shoulder at 7717 eV (corresponding to a 1s to 4p z transition) 29,40,41 . The intensity of these two transitions were shown by Li et al 41 to depend on the attachment to a surface, i.e., the pre-edge intensity increases and the shoulder decreases upon adsorption onto nanotubes, respectively.

Fig. 5Controlled potential electrolysis and CoPc2 film characterization.

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Aqueous Electrochemical Reduction of Carbon Dioxide and Carbon Monoxide into Methanol with Cobalt Phthalocyanine

“…TheC oK -edge X-ray absorption near-edge structure (XANES) spectra of the CoPc starting complex as well as the CoPc-MWCNT electrodes before and after electrolysis at À0.64 Vv s. RHE under CO atmosphere are shown in Figure 1d.T he three spectra present the typical features expected for cobalt phthalocyanine complexes: af irst, low-intensity pre-edge peak at 7710 eV which is assigned to the 1s!3d/4p transition and as econd intense peak at 7716 eV for the 1s!4p z transition which is characteristic to Co-N4 interactions. [24,25] Only slight changes are observed after catalysis,which can be attributed to changes in the interactions between CoPc and the MWCNTs. [24] A comparison of the spectrum obtained after electrolysis with those of reference cobalt species further demonstrates the intactness of the CoPc-MWCNT hybrid ( Figure S7).…”

“…[24,25] Only slight changes are observed after catalysis,which can be attributed to changes in the interactions between CoPc and the MWCNTs. [24] A comparison of the spectrum obtained after electrolysis with those of reference cobalt species further demonstrates the intactness of the CoPc-MWCNT hybrid ( Figure S7). However,i ts hould be noted that the catalytic activity progressively decreased at longer times,asobserved from the drop of the Faradaic yield for methanol production after ac ouple of hours.Itm ay be due to reductive hydrogenation of the C=N double bonds of the phthalocyanine core,w hich has already been previously reported.…”

Reactive Cobalt–Oxo Complexes of Tetrapyrrolic Macrocycles and N-based Ligand in Oxidative Transformation Reactions

“…The oxidation activity of catalyst is remarkably enhanced in the presence of bicarbonate ion (HCO 3 − ) due to the generation of (PcCo IV =O) by the heterolytic cleavage of O–O bond of peroxymonosulfate. Later, the same group [58] employed the multiwall carbon nanotubes (MWCNTs) as protein-like backbone anchored on cobalt phthalocyanine (CoPc) for peroxidase like activation of hydrogen peroxide. The anchoring of catalytic entity on MWCNTs decreases the diffusional mass transfer process (DMTP) and enhances the resistance of CoPc-MWCNTs oxidative decay.…”