Highly selective photocatalytic oxidation of methane to methyl hydroperoxide

Partial oxidation of methane into primary oxidation products with high value remains a challenge.In this work,photocatalytic oxidation of methane(CH_(4))with high methyl hydroperoxide(CH_(3)OOH)selectivity is achieved using pure titanium oxide(TiO_(2))without any cocatalyst at room temperature and atmospheric pressure.The CH_(3)OOH production rate can reach up to 2050±88μmol·g^(-1)·h^(-1) at pH≈7.0 with 100%selectivity in the liquid product.The stable reaction cycle can reach more than 30 times.This low-cost system achieves superior CH_(4) conversion activity and selectivity compared with similar work.The energy of hydrogen peroxide(H_(2)O_(2))to adsorbed hydroperoxyl radical(^(*)OOH)has a significantly lower reaction energy than conversion to adsorbed hydroxyl radical(*OH)on the(210)surface of the TiO_(2).The^(*)OOH preferentially combines with methyl radical(·CH_(3))to form the most energetically favorable CH_(3)OOH.The mild oxidative environment of this system prevents the reduction of CH_(3)OOH to CH_(3)OH or over-oxidation of CH_(4),which ensures the final CH_(3)OOH with high selectivity and stability.This work provided a low-cost but highly efficient method to achieve partial oxidation with superior selectivity,i.e.,to convert CH_(4) into high-value chemicals.