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Taranu BO, Fagadar-Cosma E. The pH Influence on the Water-Splitting Electrocatalytic Activity of Graphite Electrodes Modified with Symmetrically Substituted Metalloporphyrins. NANOMATERIALS (BASEL, SWITZERLAND) 2022; 12:3788. [PMID: 36364562 PMCID: PMC9656975 DOI: 10.3390/nano12213788] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/05/2022] [Revised: 10/19/2022] [Accepted: 10/24/2022] [Indexed: 06/16/2023]
Abstract
Hydrogen, considered to be an alternative fuel to traditional fossil fuels, can be generated by splitting water molecules into hydrogen and oxygen via the use of electrical energy, in a process whose efficiency depends directly on the employed catalytic material. The current study takes part in the relentless search for suitable and low-cost catalysts relevant to the water-splitting field by investigating the electrocatalytic properties of the O2 and H2 evolution reactions (OER and HER) of two metalloporphyrins: Zn(II) 5,10,15,20-tetrakis(4-pyridyl)-porphyrin and Co(II) 5,10,15,20-tetrakis(3-hydroxyphenyl)-porphyrin. The TEM/STEM characterisation of the porphyrin samples obtained using different organic solvents revealed several types of self-assembled aggregates. The HER and OER experiments performed on porphyrin-modified graphite electrodes in media with different pH values revealed the most electrocatalytically active specimens. For the OER, this specimen was the electrode manufactured with one layer of Co-porphyrin applied from dimethylsulfoxide, exhibiting an overpotential of 0.51 V at i = 10 mA/cm2 and a Tafel slope of 0.27 V/dec. For the HER, it was the sample obtained by drop casting one layer of Zn-porphyrin from N,N-dimethylformamide that displayed a HER overpotential of 0.52 V at i = -10 mA/cm2 and a Tafel slope of 0.15 V/dec.
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Affiliation(s)
- Bogdan-Ovidiu Taranu
- National Institute for Research and Development in Electrochemistry and Condensed Matter, Dr. A. Paunescu Podeanu Street No. 144, 300569 Timisoara, Romania
| | - Eugenia Fagadar-Cosma
- Institute of Chemistry “Coriolan Dragulescu”, Mihai Viteazu Ave. 24, 300223 Timisoara, Romania
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Fratilescu I, Lascu A, Taranu BO, Epuran C, Birdeanu M, Macsim AM, Tanasa E, Vasile E, Fagadar-Cosma E. One A3B Porphyrin Structure—Three Successful Applications. NANOMATERIALS 2022; 12:nano12111930. [PMID: 35683785 PMCID: PMC9182125 DOI: 10.3390/nano12111930] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/10/2022] [Revised: 05/26/2022] [Accepted: 06/03/2022] [Indexed: 11/16/2022]
Abstract
Porphyrins are versatile structures capable of acting in multiple ways. A mixed substituted A3B porphyrin, 5-(3-hydroxy-phenyl)-10,15,20-tris-(3-methoxy-phenyl)-porphyrin and its Pt(II) complex, were synthesised and fully characterised by 1H- and 13C-NMR, TLC, UV-Vis, FT-IR, fluorescence, AFM, TEM and SEM with EDX microscopy, both in organic solvents and in acidic mediums. The pure compounds were used, firstly, as sensitive materials for sensitive and selective optical and fluorescence detection of hydroquinone with the best results in the range 0.039–6.71 µM and a detection limit of 0.013 µM and, secondly, as corrosion inhibitors for carbon–steel (OL) in an acid medium giving a best performance of 88% in the case of coverings with Pt-porphyrin. Finally, the electrocatalytic activity for the hydrogen and oxygen evolution reactions (HER and OER) of the free-base and Pt-metalated A3B porphyrins was evaluated in strong alkaline and acidic electrolyte solutions. The best results were obtained for the electrode modified with the metalated porphyrin, drop-casted on a graphite substrate from an N,N-dimethylformamide solution. In the strong acidic medium, the electrode displayed an HER overpotential of 108 mV, at i = −10 mA/cm2 and a Tafel slope value of 205 mV/dec.
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Affiliation(s)
- Ion Fratilescu
- Institute of Chemistry “Coriolan Dragulescu”, Mihai Viteazu Ave. 24, 300223 Timisoara, Romania; (I.F.); (A.L.); (C.E.)
| | - Anca Lascu
- Institute of Chemistry “Coriolan Dragulescu”, Mihai Viteazu Ave. 24, 300223 Timisoara, Romania; (I.F.); (A.L.); (C.E.)
| | - Bogdan Ovidiu Taranu
- National Institute for Research and Development in Electrochemistry and Condensed Matter, Plautius Andronescu Street 1, 300224 Timisoara, Romania;
- Correspondence: (B.O.T.); (E.F.-C.)
| | - Camelia Epuran
- Institute of Chemistry “Coriolan Dragulescu”, Mihai Viteazu Ave. 24, 300223 Timisoara, Romania; (I.F.); (A.L.); (C.E.)
| | - Mihaela Birdeanu
- National Institute for Research and Development in Electrochemistry and Condensed Matter, Plautius Andronescu Street 1, 300224 Timisoara, Romania;
| | - Ana-Maria Macsim
- Institute of Macromolecular Chemistry “Petru Poni”, Grigore Ghica Vodă Alley, No. 41A, 700487 Iasi, Romania;
| | - Eugenia Tanasa
- Faculty of Applied Chemistry and Materials Science, University Politehnica of Bucharest, Splaiul Independentei 313, Sector 6, 060042 Bucharest, Romania; (E.T.); (E.V.)
| | - Eugeniu Vasile
- Faculty of Applied Chemistry and Materials Science, University Politehnica of Bucharest, Splaiul Independentei 313, Sector 6, 060042 Bucharest, Romania; (E.T.); (E.V.)
| | - Eugenia Fagadar-Cosma
- Institute of Chemistry “Coriolan Dragulescu”, Mihai Viteazu Ave. 24, 300223 Timisoara, Romania; (I.F.); (A.L.); (C.E.)
- Correspondence: (B.O.T.); (E.F.-C.)
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