Investigation of Electron Transfer Properties on Silicalite-1 Zeolite for Potential Electrocatalytic Applications

To develop high-performance electrocatalysts is critical to sustainable conversion and storage of renewable energy. Silicalite-1 (S-1) zeolite is considered promising for constructing electrocatalysts featuring uniform and precise porosity and a stable structural skeleton even at extreme potentials. However, its electrochemical properties remain poorly understood, particularly regarding the roles of internal pore channels. Herein, inner- and outer-sphere electron transfer (ISET/OSET) routes on the S-1 zeolite were investigated by classical redox probes. The results for the first time revealed that the ISET kinetics inside the pores of S-1 zeolite is more rapid than that on external surfaces, optimized by microporous scale channels and terminated hydroxyl groups. Conversely, the kinetics of the OSET did not closely depend on the porosity and surface properties of the S-1 zeolite. These electrochemical insights further initiated a lithium-ion-incorporated S-1 zeolite with rapid ISET kinetics for electrocatalysis of oxygen reduction. It demonstrated a high performance of 85% selectivity for H₂O₂ production in a neutral solution and a yield of 9.2 mol g_cat^-1 h^-1 when configured in a flow cell.