Unlocking ethane production in photocatalytic methanol reforming based on a novel carbon–carbon coupling mechanism

Abstract

Photocatalytic methanol reforming represents a promising solution to energy and environmental challenges, yet the CO2 by-product poses significant environmental concerns. Recent advancements enhance the economic and environmental sustainability of this process by yielding valuable by-products like ethylene and ethylene–glycol. However, synthesizing ethane (C2H6), a crucial material, remains unattainable through this reaction, with an unclear mechanism. Herein, we synthesized oxygen-deficient two-dimensional TiO2 nanosheets to achieve ethane production via methanol reforming. Through theoretical calculations and in situ characterization, we unveil a novel carbon–carbon (C–C) coupling mechanism driving ethane production. It is discovered that methanol preferentially adsorbs on the oxygen vacancies of the defective TiO2 surface, forming methoxy radicals (*CH3O), facilitating C–C coupling for ethane formation. Furthermore, prolonged hydrogenation creates additional oxygen vacancies, leading to more adjacent oxygen vacancies. This results in more neighboring *CH3O, facilitating C–C coupling and elevating C2H6 production. Our study clarifies ethane production feasibility in photocatalytic methanol reforming, providing valuable references for future research.