Size Modulation of Pt Cocatalysts Enabled the Selectivity Switching of Photocatalytic Oxidation of CH4

Abstract Direct and efficient photocatalytic oxidation of methane to the desired liquid oxygenates provides a promising pathway for sustainable chemical industry. Though many advancements have demonstrated a considerable yield of valuable liquid chemicals, including methanol (CH 3 OH), formic acid (HCOOH), and formaldehyde (HCHO), selective generation of a single product is still unsatisfactory. In this work, we propose a highly efficient strategy, based on the precise control of the type of as‐formed reactive oxygen species (ROS) by rational design of photocatalysts, to achieve both high selectivity and high productivity of CH 3 OH and CH 3 OOH in CH 4 photooxidation. By virtue of the suitable valence band position of In 2 O 3 support, which is above the oxidation potential of H 2 O to ·OH but below that of CH 4 into ·CH 3 , the left holes on the valence band specifically convert CH 4 into ·CH 3 . Meanwhile, the transferred electrons could reduce the adsorbed O 2 on Pt single atoms or Pt nanoparticles, leading to the selective formation of ·OOH and ·OH, respectively, which directly determines the selectivity of products. As a result, the formation rate of liquid oxygenates is 2966.98 µmol·g cat −1 ·h −1 over Pt 0.08 /In 2 O 3 with CH 3 OOH as the main product at a selectivity of 87.5%. Over Pt 2.3 /In 2 O 3 , and CH 3 OH was the primary product with the formation rate and selectivity of 2885.5 µmol·g cat −1 ·h −1 and 88.3%, respectively.