Hierarchiral 4-tetranitro copper(II)phthalocyanine based metal organic framework hybrid composite with improved electrocatalytic efficiency towards hydrogen evolution reaction

Gobeng Release Monama; Mpitloane Joseph Hato; Kabelo Edmond Ramohlola; Thabiso Carol Maponya; Siyabonga Beizel Mdluli; Kerileng Mildred Molapo; Kwena Desmond Modibane; Emmanuel I. Iwuoha; Katlego Makgopa; Malesela Daniel Teffu

Results in Physics (Dec 2019)

Hierarchiral 4-tetranitro copper(II)phthalocyanine based metal organic framework hybrid composite with improved electrocatalytic efficiency towards hydrogen evolution reaction

Gobeng Release Monama,
Mpitloane Joseph Hato,
Kabelo Edmond Ramohlola,
Thabiso Carol Maponya,
Siyabonga Beizel Mdluli,
Kerileng Mildred Molapo,
Kwena Desmond Modibane,
Emmanuel I. Iwuoha,
Katlego Makgopa,
Malesela Daniel Teffu

Affiliations

Gobeng Release Monama: Nanotechnology Research Lab, Department of Chemistry, School of Physical and Mineral Sciences, University of Limpopo (Turfloop), Sovenga 0727, Polokwane, South Africa; SensorLab, Chemistry Department, University of the Western Cape, Bellville 7535, Cape Town, South Africa
Mpitloane Joseph Hato: Nanotechnology Research Lab, Department of Chemistry, School of Physical and Mineral Sciences, University of Limpopo (Turfloop), Sovenga 0727, Polokwane, South Africa; Department of Environmental Sciences, College of Agriculture and Environmental Sciences, University of South Africa (UNISA), Florida Science Campus, Johannesburg 1710, South Africa; Corresponding authors at: Nanotechnology Research Lab, Department of Chemistry, School of Physical and Mineral Sciences, University of Limpopo (Turfloop), Sovenga 0727, Polokwane, South Africa (M.J. Hato).
Kabelo Edmond Ramohlola: Nanotechnology Research Lab, Department of Chemistry, School of Physical and Mineral Sciences, University of Limpopo (Turfloop), Sovenga 0727, Polokwane, South Africa
Thabiso Carol Maponya: Nanotechnology Research Lab, Department of Chemistry, School of Physical and Mineral Sciences, University of Limpopo (Turfloop), Sovenga 0727, Polokwane, South Africa
Siyabonga Beizel Mdluli: SensorLab, Chemistry Department, University of the Western Cape, Bellville 7535, Cape Town, South Africa
Kerileng Mildred Molapo: SensorLab, Chemistry Department, University of the Western Cape, Bellville 7535, Cape Town, South Africa
Kwena Desmond Modibane: Nanotechnology Research Lab, Department of Chemistry, School of Physical and Mineral Sciences, University of Limpopo (Turfloop), Sovenga 0727, Polokwane, South Africa; Corresponding authors at: Nanotechnology Research Lab, Department of Chemistry, School of Physical and Mineral Sciences, University of Limpopo (Turfloop), Sovenga 0727, Polokwane, South Africa (M.J. Hato).
Emmanuel I. Iwuoha: SensorLab, Chemistry Department, University of the Western Cape, Bellville 7535, Cape Town, South Africa
Katlego Makgopa: Department of Chemistry, Faculty of Science, Tshwane University of Technology (Acardia Campus), Pretoria 0001, South Africa
Malesela Daniel Teffu: Nanotechnology Research Lab, Department of Chemistry, School of Physical and Mineral Sciences, University of Limpopo (Turfloop), Sovenga 0727, Polokwane, South Africa

Journal volume & issue: Vol. 15

Abstract

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A novel hybrid-hybrid nanocomposite based on 4-tetranitro copper(II)phthalocyanine (TNCuPc) grown on metal organic frameworks (MOF) as a noble metal-free catalyst for hydrogen evolution reaction (HER) was developed by a simple impregnation method. The structure, surface area and the morphology of the bare MOF, TNCuPc and the TNCuPc/MOF composite were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, ultraviolet-visible spectroscopy, Brunauer-Emmet-Teller, scanning electron microscopy, transmission electron microscopy and simultaneous thermal analysis. The electrocatalytic activity of the samples towards the HER was evaluated using electrochemical impedance spectroscopy (EIS) and cyclic voltammetry, exchange current density, i0, Tafel slope value, b, as well as charge transfer coefficient, α. The spectroscopic analyses indicated a successful synthesis of TNCuPc and its composite. The morphological results showed the development of rod-like structures of TNCuPc on the surface of the MOF. The composite exhibited an onset potential of about −0.713 V vs. Ag/AgCl in 0.1 M TBAP/DMSO and 0.3 M H2SO4 solutions, which is 44 mV and 9 mV more positive than that of MOF and TNCuPc respectively. The composite showed the rate determining step (RDS) to be the Volmer reaction in conjunction with either Heyrovsky or Tafel reaction as the RDS due to the Tafel slope value of 147 mV/dec and an α of 0.4. The i0 value of the TNCuPc/MOF composite was about 1.6 times that of the bare MOF. The EIS results showed the charge transfer resistance (Rct) of 12.6 kΩ for the TNCuPc/MOF composite as compared to MOF and TNCuPc values of 41 and 18.6 kΩ, respectively, demonstrating an excellent conductivity of the composite. In addition, Rct values of materials follow the sequence, blank < MOF < TNCuPc < TNCuPc/MOF. The fabricated composite displayed high activity towards the HER, high thermal stability, and excellent tolerance. Therefore, TNCuPc/MOF non-noble electrocatalyst can be a promising electrochemical catalyst to replace Pt-based catalysts for electrochemical hydrogen production. Keywords: Copper(II)phthalocyanine, Composite, Electrocatalysis, Hydrogen evolution reaction, Tafel parameters

Published in Results in Physics

ISSN: 2211-3797 (Online)
Publisher: Elsevier
Country of publisher: Netherlands
LCC subjects: Science: Physics
Website: http://www.journals.elsevier.com/results-in-physics/

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