Direct functionalization of methane into ethanol over copper modified polymeric carbon nitride via photocatalysis

Yuanyi Zhou,Ling Zhang,Wenzhong Wang

doi:10.1038/s41467-019-08454-0

Abstract

Direct valorization of methane to its alcohol derivative remains a great challenge. Photocatalysis arises as a promising green strategy which could exploit hydroxyl radical (·OH) to accomplish methane activation. However, both the excessive ·OH from direct H2O oxidation and the neglect of methane activation on the material would cause deep mineralization. Here we introduce Cu species into polymeric carbon nitride (PCN), accomplishing photocatalytic anaerobic methane conversion for the first time with an ethanol productivity of 106 μmol gcat−1 h−1. Cu modified PCN could manage generation and in situ decomposition of H2O2 to produce ·OH, of which Cu species are also active sites for methane adsorption and activation. These features avoid excess ·OH for overoxidation and facilitate methane conversion. Moreover, a hypothetic mechanism through a methane-methanol-ethanol pathway is proposed, emphasizing the synergy of Cu species and the adjacent C atom in PCN for obtaining C2 product.

Highlights

Direct valorization of methane to its alcohol derivative remains a great challenge
The samples were prepared by thermal condensation of the precursor, denoted as polymeric carbon nitride (PCN) or Cu-X/ PCN, where X corresponds to the theoretical weight percentage of Cu
Chemical structure of PCN and a series of Cu-X/PCN was first characterized by X-ray diffraction (XRD)

Summary

Introduction

Photocatalysis arises as a promising green strategy which could exploit hydroxyl radical (·OH) to accomplish methane activation. Both the excessive ·OH from direct H2O oxidation and the neglect of methane activation on the material would cause deep mineralization. It is hard to preserve the products from deep mineralization under practical situations since all the derivatives are easier to become activated for oxidation[6] Such prospects and challenges of methane conversion have captured the interest of both academic community and industry. The dominant way to activate methane is oxidizing H2O directly to produce ·OH, which would abstract a hydrogen atom from methane to generate methyl radical

Methods

Results

Conclusion