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Wang G, Ren R, Feng X, Wang Y, Meng J, Jia J. First-principle calculations study of the ORR/OER electrocatalytic activity of ruthenium polyphthalocyanine axially modified with aliphatic thiol groups. Phys Chem Chem Phys 2024; 26:16207-16217. [PMID: 38804323 DOI: 10.1039/d4cp00424h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/29/2024]
Abstract
In this study, the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) catalytic activity of ruthenium polyphthalocyanine axially modified with different aliphatic thiol groups, RuPPc-SR (SR = -SCH3, -SC2H5, -SC3H7, -SC4H9, -SC5H11, and -SC6H13), in an acidic medium were simulated using DFT. All -SR groups can effectively enhance the ORR and OER catalytic activities of RuPPc. The ORR and OER overpotentials of RuPPc-SC4H9 are 0.237 V and 0.436 V, respectively, which are far lower than those of RuPPc (0.960 V and 0.903 V). For RuPPc-SC4H9, the four C and S atoms of the -SC4H9 chain and Ru atom are coplanar, and thus, conjugate effects and inductive effects exist between the -SC4H9 chain and Ru atom. This makes the Ru atom exhibit the least positive Bader charge and smallest spin density, and the anti-bonding orbitals of dxz, dyz, and dz2 of the Ru atom shift below the Fermi level (Ef). This makes the adsorption strength of RuPPc-SC4H9 toward ORR and OER intermediates the weakest, which accelerates the reaction process, thus resulting in better ORR and OER catalytic activity. Therefore, the introduction of the aliphatic thiol groups might effectively improve the OER/ORR catalytic activity of RuPPc.
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Affiliation(s)
- Guilin Wang
- Key Laboratory of Magnetic Molecules and Magnetic Information Materials (Ministry of Education), School of Chemistry and Material Science, Shanxi Normal University, Taiyuan 030031, China.
- Department of Physics and Electronic Engineering, Yuncheng University, Yuncheng 044000, China
| | - Rongrong Ren
- Key Laboratory of Magnetic Molecules and Magnetic Information Materials (Ministry of Education), School of Chemistry and Material Science, Shanxi Normal University, Taiyuan 030031, China.
| | - Xiaoqin Feng
- Key Laboratory of Magnetic Molecules and Magnetic Information Materials (Ministry of Education), School of Chemistry and Material Science, Shanxi Normal University, Taiyuan 030031, China.
| | - Yuxin Wang
- Key Laboratory of Magnetic Molecules and Magnetic Information Materials (Ministry of Education), School of Chemistry and Material Science, Shanxi Normal University, Taiyuan 030031, China.
| | - Jie Meng
- Key Laboratory of Magnetic Molecules and Magnetic Information Materials (Ministry of Education), School of Chemistry and Material Science, Shanxi Normal University, Taiyuan 030031, China.
| | - Jianfeng Jia
- Key Laboratory of Magnetic Molecules and Magnetic Information Materials (Ministry of Education), School of Chemistry and Material Science, Shanxi Normal University, Taiyuan 030031, China.
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Wang G, Yang X, Wang R, Jia J. A theoretical study on the ORR electrocatalytic activity of axial ligand modified cobalt polyphthalocyanine. Phys Chem Chem Phys 2023; 25:27342-27351. [PMID: 37791783 DOI: 10.1039/d3cp03707j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/05/2023]
Abstract
In this work, the catalytic activity in the oxygen reduction reaction (ORR) of cobalt polyphthalocyanine whose central Co atom is coordinated at the axial position by ligands (L = -F, -OH, -OCH3, -N3, -Cl, -Br, -I, -SCN, and -CN) (CoPPc-L) was investigated using theoretical calculations in alkaline medium. Among all CoPPc-L, CoPPc-N3 exhibited the lowest ORR overpotential of 0.23 V vs. a standard hydrogen electrode, which is significantly lower than those of CoPPc (0.48 V) and Pt(111) (0.43 V). There is a good linear relationship between ΔG*OOH and the electronegativity of ligating atoms in axial ligands of CoPPc-L. The greater the electronegativity, the stronger the adsorption of the catalyst to the intermediate. Additionally, the adsorption strength of CoPPc to the intermediate is modified by the axial ligands, which adjust the distribution of anti-bonding electronic states of dz2, dxz, and dyz orbitals near the Fermi level, Ef. A larger Mayer bond order of the Co-L bond resulted in a smaller bond order of the Co-O bond. CoPPc-N3 exhibited a moderate Co-O bond order of 0.737, corresponding to moderate adsorption energy to the OOH intermediate. This study demonstrates that the interaction strength between CoPPc and ORR intermediates can be adjusted by selecting appropriate axial ligands, which can modulate the ORR catalytic activity.
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Affiliation(s)
- Guilin Wang
- Key Laboratory of Magnetic Molecules and Magnetic Information Materials (Ministry of Education), School of Chemistry and Material Science, Shanxi Normal University, Taiyuan 030031, China.
- Department of Physics and Electronic Engineering, Yuncheng University, Yuncheng 044000, China
| | - Xiaoli Yang
- Key Laboratory of Magnetic Molecules and Magnetic Information Materials (Ministry of Education), School of Chemistry and Material Science, Shanxi Normal University, Taiyuan 030031, China.
| | - Ruiying Wang
- Key Laboratory of Magnetic Molecules and Magnetic Information Materials (Ministry of Education), School of Chemistry and Material Science, Shanxi Normal University, Taiyuan 030031, China.
| | - Jianfeng Jia
- Key Laboratory of Magnetic Molecules and Magnetic Information Materials (Ministry of Education), School of Chemistry and Material Science, Shanxi Normal University, Taiyuan 030031, China.
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Chen P, Fan D, Selloni A, Carter EA, Arnold CB, Zhang Y, Gross AS, Chelikowsky JR, Yao N. Observation of electron orbital signatures of single atoms within metal-phthalocyanines using atomic force microscopy. Nat Commun 2023; 14:1460. [PMID: 36928085 PMCID: PMC10020477 DOI: 10.1038/s41467-023-37023-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2022] [Accepted: 02/20/2023] [Indexed: 03/18/2023] Open
Abstract
Resolving the electronic structure of a single atom within a molecule is of fundamental importance for understanding and predicting chemical and physical properties of functional molecules such as molecular catalysts. However, the observation of the orbital signature of an individual atom is challenging. We report here the direct identification of two adjacent transition-metal atoms, Fe and Co, within phthalocyanine molecules using high-resolution noncontact atomic force microscopy (HR-AFM). HR-AFM imaging reveals that the Co atom is brighter and presents four distinct lobes on the horizontal plane whereas the Fe atom displays a "square" morphology. Pico-force spectroscopy measurements show a larger repulsion force of about 5 pN on the tip exerted by Co in comparison to Fe. Our combined experimental and theoretical results demonstrate that both the distinguishable features in AFM images and the variation in the measured forces arise from Co's higher electron orbital occupation above the molecular plane. The ability to directly observe orbital signatures using HR-AFM should provide a promising approach to characterizing the electronic structure of an individual atom in a molecular species and to understand mechanisms of certain chemical reactions.
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Affiliation(s)
- Pengcheng Chen
- Princeton Materials Institute, Princeton University, Princeton, NJ, 08540-8211, USA
| | - Dingxin Fan
- Princeton Materials Institute, Princeton University, Princeton, NJ, 08540-8211, USA.,McKetta Department of Chemical Engineering, University of Texas at Austin, Austin, TX, 78712-1589, USA
| | - Annabella Selloni
- Department of Chemistry, Princeton University, Princeton, NJ, 08544-0001, USA
| | - Emily A Carter
- Department of Mechanical and Aerospace Engineering and the Andlinger Center for Energy and the Environment, Princeton University, Princeton, NJ, 08544-5263, USA.,Princeton Plasma Physics Laboratory, Princeton, NJ, 08540-6655, USA
| | - Craig B Arnold
- Princeton Materials Institute, Princeton University, Princeton, NJ, 08540-8211, USA.,Department of Mechanical and Aerospace Engineering and the Andlinger Center for Energy and the Environment, Princeton University, Princeton, NJ, 08544-5263, USA
| | - Yunlong Zhang
- ExxonMobil Technology and Engineering Company, Annandale, NJ, 08801-3096, USA
| | - Adam S Gross
- ExxonMobil Technology and Engineering Company, Annandale, NJ, 08801-3096, USA
| | - James R Chelikowsky
- McKetta Department of Chemical Engineering, University of Texas at Austin, Austin, TX, 78712-1589, USA. .,Department of Physics, University of Texas at Austin, Austin, TX, 78712-1192, USA. .,Center for Computational Materials, Oden Institute for Computational Engineering and Sciences, University of Texas at Austin, Austin, TX, 78712-1229, USA.
| | - Nan Yao
- Princeton Materials Institute, Princeton University, Princeton, NJ, 08540-8211, USA.
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Wang YZ, Hsieh TH, Huang YC, Ho KS. 2,6-Diaminopyridine-Based Polyurea as an ORR Electrocatalyst of an Anion Exchange Membrane Fuel Cell. Polymers (Basel) 2023; 15:polym15040915. [PMID: 36850199 PMCID: PMC9965045 DOI: 10.3390/polym15040915] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2023] [Revised: 01/25/2023] [Accepted: 02/08/2023] [Indexed: 02/15/2023] Open
Abstract
In order to yield more Co(II), 2,6-diaminopyridine (DAP) was polymerized with 4,4-methylene diphenyl diisocyanates (MDI) in the presence of Co(II) to obtain a Co-complexed polyurea (Co-PUr). The obtained Co-PUr was calcined to become Co, N-doped carbon (Co-N-C) as the cathode catalyst of an anion exchange membrane fuel cell (AEMFC). High-resolution transmission electron microscopy (HR-TEM) of Co-N-C indicated many Co-Nx (Co covalent bonding with several nitrogen) units in the Co-N-C matrix. X-ray diffraction patterns showed that carbon and cobalt crystallized in the Co-N-C catalysts. The Raman spectra showed that the carbon matrix of Co-N-C became ordered with increased calcination temperature. The surface area (dominated by micropores) of Co-N-Cs also increased with the calcination temperature. The non-precious Co-N-C demonstrated comparable electrochemical properties (oxygen reduction reaction: ORR) to commercial precious Pt/C, such as high on-set and half-wave voltages, high limited reduction current density, and lower Tafel slope. The number of electrons transferred in the cathode was close to four, indicating complete ORR. The max. power density (Pmax) of the single cell with the Co-N-C cathode catalyst demonstrated a high value of 227.7 mWcm-2.
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Affiliation(s)
- Yen-Zen Wang
- Department of Chemical and Materials Engineering, National Yu-Lin University of Science & Technology, 123, Sec. 3, University Rd., Yun-Lin 64301, Taiwan
| | - Tar-Hwa Hsieh
- Department of Chemical and Materials Engineering, National Kaohsiung University of Science and Technology, 415, Chien-Kuo Road, Kaohsiung 80782, Taiwan
| | - Yu-Chang Huang
- Department of Chemical and Materials Engineering, National Kaohsiung University of Science and Technology, 415, Chien-Kuo Road, Kaohsiung 80782, Taiwan
| | - Ko-Shan Ho
- Department of Chemical and Materials Engineering, National Kaohsiung University of Science and Technology, 415, Chien-Kuo Road, Kaohsiung 80782, Taiwan
- Correspondence:
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