Sustainable oxidation catalysis supported by light: Fe-poly (heptazine imide) as a heterogeneous single-atom photocatalyst

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da Silva, Marcos A. R. ; Silva, Ingrid F. ; Xue, Qi ; Lo, Benedict T. W. ; Tarakina, Nadezda, V ; Nunes, Barbara N. ; Adler, Peter ; Sahoo, Sudhir K. ; Bahnemann, Detlef W. ; Lopez-Salas, Nieves ; Savateev, Aleksandr ; Ribeiro, Caue ; Kuhne, Thomas D. ; Antonietti, Markus ; Teixeira, Ivo F.

• Document type: Journal article
• Source: APPLIED CATALYSIS B-ENVIRONMENTAL; v. 304, p. 11-pg., 2022-05-01.

Abstract

Fe-N-C materials, when prepared as single-atom catalysts (SAC), display excellent activities in oxidation reactions. The systematic investigation of the iron coordination mode revealed that Fe-N4C catalysts are the most active for C-H bond oxidation. However, many of these catalysts are synthesized through pyrolysis, which is characterized by a lack of control and structures with heterogeneous composition, rarely presenting only atomically dispersed Fe-N-C as active sites. Herein, an alternative, reliable and easily reproducible method to obtain highly active Fe SACs (atomically dispersed) with Fe-N4 sites is presented, which is based on ion exchange of sodium from high crystalline sodium poly(heptazine imide) (Na-PHI) by other ions. The obtained catalyst can photocatalytically oxidize C-H bonds selectively toward ketones using only dioxygen. Detailed mechanism investigations indicate that the active species in the C-H bond oxidation are highly valent Fe(IV)/Fe(V)-oxo species, which are further activated by the holes generated at the PHI support under light irradiation. (AU)

• FAPESP's process: 21/11162-8 - Multi-user equipment approved in grant 2020/14741-6: GC-MS/FID/TCD (2 injetores+Loop+Sistema valvulado)
• Grantee: Ivo Freitas Teixeira
• Support Opportunities: Multi-user Equipment Program
• FAPESP's process: 20/14741-6 - Graphitic carbon nitrides as platforms for single-atom photocatalysis: moving towards design principles for improved performance
• Grantee: Ivo Freitas Teixeira
• Support Opportunities: Research Grants - Young Investigators Grants