A noble-metal-free, nickel(II)-doped MgO/Al2O3 catalyst for highly selective photothermal coupling of methane to ethane

Selective coupling of methane into high-value-added chemicals under mild conditions is a grand challenge since activation of the inert C–H bonds and inhibition of methane from over-oxidation are simultaneously required. Here, we report the fabrication of a noble-metal-free, Ni2+-doped MgO/Al2O3 photocatalyst where the Ni2+ ions are isomorphically doped into an MgO cell. By involving trace amounts of water, photothermal conversion of methane to ethane can be accomplished in a flow reactor with a high ethane production rate of 454.30 μmol g−1 h−1 and a superior selectivity of 97.8%. Detailed characterizations reveal that the electron-enriched oxygen species are the active sites in methane activation. The involved H2O repairs the oxygen defects generated during the reaction process and induces the reaction into the coupling conductive pathway, resulting in an increased catalytic stability and C2H6 selectivity.