Covalently Grafting Graphene onto Si Photocathode to Expedite Aqueous Photoelectrochemical CO2 Reduction

Zhihe Wei; Yanhui Su; Weiyi Pan; Junxia Shen; Ronglei Fan; Wenjun Yang; Zhao Deng; Mingrong Shen; Yang Peng

doi:10.1002/anie.202305558

Covalently Grafting Graphene onto Si Photocathode to Expedite Aqueous Photoelectrochemical CO₂ Reduction

Angew Chem Int Ed Engl. 2023 Jul 10;62(28):e202305558. doi: 10.1002/anie.202305558. Epub 2023 Jun 1.

Authors

Zhihe Wei^{1

2

3}, Yanhui Su^{1

2}, Weiyi Pan^{1

2}, Junxia Shen³, Ronglei Fan³, Wenjun Yang^{1

2}, Zhao Deng^{1

2}, Mingrong Shen³, Yang Peng^{1

2}

Affiliations

¹ Soochow Institute of Energy and Material Innovations, College of Energy, Soochow University, Suzhou, 215006, China.
² Jiangsu Key Laboratory of Advanced Negative Carbon Technologies, Soochow University, Suzhou, 215123, Jiangsu, P. R. China.
³ School of Physical Science and Technology, Jiangsu Key Laboratory of Thin Films, Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University, Suzhou, 215006, China.

PMID: 37173611
DOI: 10.1002/anie.202305558

Abstract

Silicon semiconductor functionalized with molecular catalysts emerges as a promising cathode for photoelectrochemical (PEC) CO₂ reduction reaction (CO₂ RR). However, the limited kinetics and stabilities remains a major hurdle for the development of such composites. We herein report an assembling strategy of silicon photocathodes via chemically grafting a conductive graphene layer onto the surface of n⁺ -p Si followed by catalyst immobilization. The covalently-linked graphene layer effectively enhances the photogenerated carriers transfer between the cathode and the reduction catalyst, and improves the operating stability of the electrode. Strikingly, we demonstrate that altering the stacking configuration of the immobilized cobalt tetraphenylporphyrin (CoTPP) catalyst through calcination can further enhance the electron transfer rate and the PEC performance. At the end, the graphene-coated Si cathode immobilized with CoTPP catalyst managed to sustain a stable 1-Sun photocurrent of -1.65 mA cm^-2 over 16 h for CO production in water at a near neutral potential of -0.1 V vs. reversible hydrogen electrode. This represents a remarkable improvement of PEC CO₂ RR performance in contrast to the reported photocathodes functionalized with molecular catalysts.

Keywords: CO2 Reduction; Graphene; Molecular Catalyst; Photoelectrochemical Reaction; Silicon Photocathode.

Abstract

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