An Ad-Hoc Pyrolized Phoenix-like Covalent Triazine Framework for the Selective CO₂-to-Formate Electroreduction

Selective electrochemical CO2 reduction reaction (CO2RR) to formic acid (HCOOH) represents a promising strategy for renewable energy storage other than being a key environmental route for CO2 recycling/mitigation. Covalent triazine frameworks (CTFs) are highly versatile N,C nanoarchitectures whose employment for electrochemical CO2RR as metal-based composites or metal-free systems has been documented in a number of seminal contributions. Here, we unveiled a silent electrochemical potentiality of a metal-free CTF sample already known as only moderately active in the CO2-to-CO electroreduction. Ad-hoc pyrolysis conditions gave rise to a unique and robust metal-free CTF catalyst with superior CO2RR selectivity toward the almost exclusive production of formic acid, at low overpotential values in aqueous electrolyte (FEHCOOH as high as 66% at -0.4 V vs. RHE). As a modern phoenix, the mythological bird that regenerates from its own ashes, the CTFph material described in this contribution demonstrates the impact that pyrolysis conditions have on the ultimate electrochemical properties of these samples.