Steering Photooxidation of Methane to Formic Acid over A Priori Screened Supported Catalysts

Abstract

Efficient methane photooxidation to formic acid (HCOOH) has emerged as a sustainable approach to simultaneously generate value-added chemicals and harness renewable energy. However, the persistent challenge lies in achieving a high yield and selectivity for HCOOH formation, primarily due to the complexities associated with modulating intermediate conversion and desorption after methane activation. In this study, we employ first-principles calculations as a comprehensive guiding tool and discover that by precisely controlling the O₂ activation process on noble metal cocatalysts and the adsorption strength of carbon-containing intermediates on metal oxide supports, one can finely tune the selectivity of methane photooxidation products. Specifically, a bifunctional catalyst comprising Pd nanoparticles and monoclinic WO₃ (Pd/WO₃) would possess optimal O₂ activation kinetics and an intermediate oxidation/desorption barrier, thereby promoting HCOOH formation. As evidenced by experiments, the Pd/WO₃ catalyst achieves an exceptional HCOOH yield of 4.67 mmol g_cat^-1 h^-1 with a high selectivity of 62% under full-spectrum light irradiation at room temperature using molecular O₂. Notably, these results significantly outperform the state-of-the-art photocatalytic systems operated under identical condition.