Oxygen Serves as an Electron Acceptor for Efficient Photocatalytic Acetylene Hydrochlorination in Seawater

Abstract

ABSTRACT The photocatalytic acetylene hydrochlorination with H 2 O as hydrogen source and Cl – as chlorine source in seawater is a highly promising alternative to traditional thermocatalytic acetylene hydrochlorination, but seriously suffers from poor performance due to the rapid recombination of photogenerated electrons and holes as well as the sluggish redox kinetics caused by low H + and Cl – concentrations. Here, we report an O 2 ‐accelerated photocatalytic acetylene hydrochlorination in seawater, where the O 2 serves as an efficient electron acceptor for rapidly consuming photo‐generated electrons. Consequently, the as‐fabricated tubular carbon nitride photocatalyst (MTA‐C 3 N 4 ) delivers a substantially enhanced vinyl chloride monomer (VCM) production rate of 567.0 µmol g cat −1 h −1 under 420 nm light‐emitting diode (LED) irradiation in simulated seawater with O 2 , which is ∼66‐fold higher than that without O 2 . Even in natural seawater, the MTA‐C 3 N 4 maintains a stable VCM production rate of 433.3 µmol g cat −1 h −1 over 10 days. Mechanistic studies reveal that O 2 acts as an electron acceptor to suppress charge recombination and promote the formation of holes, thereby accelerating the hole‐driven chloride oxidation kinetics to generate *Cl for selective acetylene hydrochlorination. This work not only reveals the vital role of molecular oxygen in photoredox kinetics, but also provides an appealing strategy for enhancing photocatalytic performance.