Well-exposed gold nanoclusters on Indonesia natural zeolite: a highly active and reusable catalyst for the reduction of p-nitrophenol

Herein we report the synthesis of gold nanoclusters upon the surface of Indonesia natural zeolite, denoted as Au/INZ. The as-prepared material has been characterized using X-ray diffraction, atomic absorption spectroscopy, UV–Vis diffuse reflectance spectroscopy, transmission electron microscopy, selected area electron diffraction and N₂ physisorption. These characterizations confirm the well-defined gold nanoclusters formed on the surface of Au/INZ. Our catalyst has been applied for the reduction of p-nitrophenol to p-aminophenol. The reduction conversion of ca. 95 % was achieved by the use of 50 mg Au/INZ for 10 min with the observed rate constant (k_obs) was of 0.818 min⁻¹. The E_a of the reaction was 16.9 kJ/mol, indicating the diffusion-controlled mechanism. In addition, the reusability test confirmed that our catalyst can be exploited for several times without the significant loss of its high activity.