Near‐100% Selective Photocatalytic Methane‐to‐Methanol Conversion Enabled by Synergistic Chlorine Radicals and Oxygen Vacancies

Abstract

ABSTRACT The selective photocatalytic conversion of methane to a single product is a grand challenge, primarily due to uncontrollable over‐oxidation and inefficient reduction. Herein, we pioneer a radical/active‐site synergistic strategy to steer the reaction pathway exclusively toward methanol. This is realized by a dual‐functional Cl─TiO 2 ‐OV catalyst that integrates chlorine modification and oxygen vacancy (OV) engineering. Crucially, surface chlorine redirects the oxidation route: instead of generating non‐selective •OH radicals from H 2 O, photogenerated holes preferentially drive a Cl − /Cl• cycle. The resulting Cl• radicals activate the C─H bond of CH 4 to form •CH 3 , which combines with O 2 to yield the CH 3 OOH intermediate. Simultaneously, the engineered OV sites act as electron‐rich centers that efficiently reduce CH 3 OOH to CH 3 OH. This decoupling of selective oxidation (via Cl•) and efficient reduction (via OVs) suppresses all side‐reactions, delivering methanol with nearly 100% selectivity and a yield of 1242 µmol g −1 . In contrast, TiO 2 ‐OV suffers from •OH‐mediated sequential oxidation to HCHO/CO 2 , and Cl─TiO 2 lacks sufficient reduction power, resulting in a CH 3 OOH/CH 3 OH mixture. This work not only offers an effective approach for highly selective photocatalytic methane conversion but also deepens mechanistic insight into radical/active‐site cooperativity in synergistic catalysis.