High-energy Charge Separation State for Photocatalytic Nonoxidative Methane Conversion

Abstract

The nonoxidative coupling of methane (NOCM) under mild conditions is a promising technique for low-cost H2 and carbon feedstock productions. Here, we fabricate a Ce-Zr solid solution photocatalyst containing nonstoichiometric CeO2 − x nano-islands with stepped surfaces and abundant oxygen vacancies, enabling unprecedented adsorption of methane and ideal for the photocatalytic NOCM at room temperature. It is revealed that the Ce-Zr photocatalyst can undergo a cooperative and reversible photo-induced transition from the initial resting state to the charge-separation state that stores sufficient energy to dissociate the inert methane C-H bond, thereby resulting in excellent photocatalytic activity with long-term stability (> 40 h, > 20 cycles) and high selectivity, exceeding that of traditional Ce-based photocatalysts by two orders of magnitude. This work not only provides fresh insight into the catalyst design for methane conversion but also extends the boundaries of conventional photocatalysts with the unique ability of storage and delayed release of solar energy.

Concepts of Computational Approach to Explore Heterogeneous Catalysts for Direct Methane Conversion

“…Because NOCM does not require oxidants, undesirable CO x species are not produced. [35,36] In addition, H 2 is coproduced as a valuable byproduct. [37] These factors make NOCM more attractive than OCM.…”