PdAu/TiO2 nanoparticles: transforming methane to methanol for clean energy in PEM fuel cell reactors

Introduction: Methane valorization through its direct conversion into value-added chemicals is an attractive strategy for mitigating greenhouse gas emissions while producing high-value chemicals. In this study, the selective electrochemical oxidation of methane to methanol was investigated using a polymer electrolyte membrane (PEM) fuel cell reactor and PdAu bimetallic electrocatalysts supported on TiO2. Materials and methods: PdAu/TiO2 electrocatalysts with different Pd:Au compositions were synthesized and structurally characterized by transmission electron microscopy (TEM) and X-ray diffraction (XRD). Their electrocatalytic performance toward methane oxidation was evaluated in a PEM fuel cell reactor under mild operating conditions by measuring methanol production at different applied potentials. Results: TEM and XRD analyses confirmed the formation of PdAu nanoparticles with average particle sizes ranging from 5.0 to 8.0 nm. The incorporation of Au into Pd-based catalysts induced structural and electrochemical modifications, which influenced their catalytic performance for methane-to-methanol conversion. Among the investigated catalysts, Pd50Au50/TiO2 exhibited the highest methanol production rate, reaching 10.61 µmol cm−2 h−1 at an applied potential of 0.1 V. The superior performance of Pd50Au50/TiO2 may be associated with the specific Pd/Au composition and the resulting structural and electrochemical characteristics of the catalyst, which favored methanol formation under the investigated conditions. Conclusions: The results demonstrate that PdAu/TiO2 bimetallic electrocatalysts are promising materials for the electrochemical conversion of methane to methanol under mild conditions. In particular, the Pd50Au50/TiO2 catalyst exhibited the highest methanol production rate among the investigated catalysts, indicating that the Pd/Au composition plays an important role in the catalytic performance. These findings provide valuable insights into the development of efficient electrocatalysts for methane valorization and support the potential application of PEM fuel cell reactors for electrochemical methane-to-methanol conversion.