Ambient catalyst-free conversion of methane to methanol by water radical cations.

Methane combustion contributes 30% to global warming, making its conversion to cleaner chemicals a critical challenge. Here, we report a catalyst-free ambient conversion of methane to methanol with a remarkable yield exceeding 650 millimoles per hour and a high conversion rate of ~35%, achieved using in situ-generated water dimer radical cations, [Formula: see text] , in a specially designed batch reactor operating under mild conditions. In a single run, the reactor was typically operated for 10 minutes. The atom efficiency for hydrogen in our approach for methanol synthesis is ~67%. Hydrogen gas is the by-product, produced at a rate of over 2 millimoles per hour. Compared to the previously reported catalytic methods, our production yields are up by between 10 and 10 times depending on the literature method. This breakthrough enables clean, energy-efficient methane conversion without unwanted oxidation by-products, offering substantial environmental and economic benefits beyond combustion.