An Efficient and Durable Electrocatalyst Based on Strongly Coupled Pt Nanoparticles on CeO₂Microspheres for CO-Resilient Methanol Oxidation

Designing durable, highly active supported Pt catalysts has attracted tremendous interest in recent years due to their high electrocatalytic activities and stability in methanol oxidation reactions (MORs). Herein, we report an eco-friendly synthetic strategy for obtaining Pt/CeO₂composite microspheres, which are highly active and durable catalysts for MOR. The porous CeO₂microspheres were prepared through a hydrothermal method using the Piper longum fruit extract, which is an environmentally friendly solvent. The Pt nanoparticles (NPs) with an average size of ∼5 nm dispersed on CeO₂microspheres were obtained by the chemical reduction of Pt²⁺ions at room temperature. It was found that the supported Pt NPs are strongly coupled through strong metal-support interactions (SMSIs), which promoted the formation of oxygen vacancies (OVs) and increased the concentration of active Ce³⁺sites. Owing to the presence of high OVs and of Ce³⁺species, the Pt/CeO₂microsphere catalyst revealed enhanced MOR performance, with specific activity (SA) as high as 36.37 mA/cm²and mass activity (MA) of 229.44 mA/mg, which are substantially higher than those of commercial catalysts such as Pt/C and Pt/CeO₂prepared with commercial CeO₂nanoparticles. Moreover, the resultant catalyst showed excellent durability, retaining about 76.2% of its initial current density even after 5000 potential cycles. The used green extract-mediated synthesis process can be a promising alternative to conventional methods for the rational design of highly active metal nanoparticle-supported catalysts for heterogeneous catalysts.