Modulating the Band Structure of Metal Coordinated Salen COFs and an In Situ Constructed Charge Transfer Heterostructure for Electrocatalysis Hydrogen Evolution

Boying Zhang; Liling Chen; Zhenni Zhang; Qing Li; Phathutshedzo Khangale; Diane Hildebrandt; Xinying Liu; Qingliang Feng; Shanlin Qiao

doi:10.1002/advs.202105912

Modulating the Band Structure of Metal Coordinated Salen COFs and an In Situ Constructed Charge Transfer Heterostructure for Electrocatalysis Hydrogen Evolution

Adv Sci (Weinh). 2022 Aug;9(22):e2105912. doi: 10.1002/advs.202105912. Epub 2022 Jun 3.

Authors

Boying Zhang^{1

2}, Liling Chen^{1

3}, Zhenni Zhang¹, Qing Li¹, Phathutshedzo Khangale², Diane Hildebrandt⁴, Xinying Liu⁵, Qingliang Feng³, Shanlin Qiao^{1

6}

Affiliations

¹ College of Chemistry and Pharmaceutical Engineering, Hebei University of Science and Technology, Shijiazhuang, 050018, P. R. China.
² Department of Chemical Engineering, Faculty of Engineering and the Built Environment, University of Johannesburg, Doornfontein, 2028, South Africa.
³ Key Laboratory of Special Functional and Smart Polymer Materials of Ministry of Industry and Information Technology School of Chemistry and Chemical Engineering, Northwestern Polytechnical University, Xi'an, 710072, P. R. China.
⁴ African Energy Leadership Centre, WITS Business School and Molecular Science Institute, School of Chemistry, University of Witwatersrand, Johannesburg, 2050, South Africa.
⁵ Institute for Development of Energy for African Sustainability, University of South Africa, Florida, 1709, South Africa.
⁶ Hebei Electronic Organic Chemicals Technology Innovation Center, Shijiazhuang, 050018, P. R. China.

Abstract

A series of crystalline, stable Metal (Metal = Zn, Cu, Ni, Co, Fe, and Mn)-Salen covalent organic framework (COF)_EDA complex are prepared to continuously tune the band structure of Metal-Salen COF_EDA , with the purpose of optimizing the free energy intermediate species during the hydrogen evolution reaction (HER) process. The conductive macromolecular poly(3,4-ethylenedioxythiophene) (PEDOT) is subsequently integrated into the one-dimensional (1D) channel arrays of Metal-Salen COF_EDA to form heterostructure PEDOT@Metal-Salen COF_EDA via the in situ solid-state polymerization method. Among the Metal-Salen COF_EDA and PEDOT@Metal-Salen COF_EDA complexes, the optimized PEDOT@Mn-Salen COF_EDA displays prominent electrochemical activity with an overpotential of 150 mV and a Tafel slope of 43 mV dec^-1 . The experimental results and density of states data show that the continuous energy band structure modulation in Metal-Salen COF_EDA has the ability to make the metal d-orbital interact better with the s-orbital of H, which is conducive to electron transport in the HER process. Moreover, the calculated charge density difference indicates that the heterostructures composed of PEDOT and Metal-Salen COF_EDA induce an intramolecular charge transfer and construct highly active interfacial sites.

Keywords: Salen covalent organic frameworks (COFs); band structure modulation; heterostructures; hydrogen evolution reaction; in situ solid-state polymerization.

Abstract

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