Lattice-Disordered Boron Nitride Colloidal Catalyst for Low-Temperature Selective Methane Oxidation

Abstract

Metal-free boron nitride (BN) catalysts hold great potential in numerous significant reactions, particularly in the selective oxidation of light alkanes, due to their unique ability to suppress overoxidation. However, the chemically stable BN catalysts often require high reaction temperatures, resulting in elevated energy consumption and less favorable for valuable oxygenate production. Enhancing the structural disorder within BN, increasing the density and refining the operational system are crucial for low-temperature applications, but modifying the inherently inert BN structure remains a significant challenge. Here, we report the controllable synthesis of lattice-disordered BN colloids by tailoring the defects. Spectroscopic, microscopic, and theoretical experiments revealed that increasing the number of vacancies in adjacent layers of hexagonal or porous BN leads to the formation of lattice-disordered structures. By employing the colloidal BN catalysts in the direct conversion of methane, an important greenhouse gas, into C1 oxygenates below 100 degrees C using H2O2 as a green oxidant, we achieved both high mass activity and selectivity (exceeding 90%), which is an order of magnitude higher than fresh hexagonal BN powder and rivaling conventional metal catalysts. Mechanistic investigations highlighted that the lattice-disordered BN catalyst follows a radical pathway for the C1 oxygenate production. Moreover, the disordered boron species are proposed to enable facile activation of reactants due to their enhanced structural flexibility.