Defect-healing driven stable Pt species formation in Silicalite-1 zeolite for base-free alcohol oxidation in water

Jingyi Chen, ^†1 Shuangfeng Ren, ^†1,2 Luyao Guo, ^†3 Tongtong Feng,^1,3 Xiaoling Mou,*¹ Jiaxu Liu,³* Li Yan,² Ronghe Lin,*¹ and Yunjie Ding*^1,2

Abstract

The development of robust Pt catalysts that simultaneously achieve efficient O₂ activation, high intrinsic activity, and structural stability remains a central challenge in aerobic alcohol oxidation. Herein, we report a hydrothermal defect-healing strategy to restructure impregnated weakly anchored Pt species in Silicalite-1 zeolite into highly stable Pt ensembles confined within the zeolite framework (Pt@S-1). Spectroscopic and microscopic analyses reveal that hydrothermal treatment heals silanol defects and drives controlled restructuring of isolated Pt atoms into small ensembles strongly stabilized by the zeolitic microenvironment. The resulting Pt@S-1 catalyst exhibits markedly enhanced intrinsic activity, achieving a turnover frequency of 5560 h^-1 in aqueous aerobic oxidation of 3,5,5-trimethylhexanol, exceeding conventional nanoparticle and impregnated analogues by over one order of magnitude despite significantly lower Pt loading. Kinetic studies demonstrate a reduced apparent activation energy (65.7 kJ mol^-1) and nearly first-order dependence on O₂ pressure, indicating facilitated O₂ activation and optimized competitive adsorption between oxygen and alcohol substrates. The zeolite confinement and aqueous reaction medium synergistically promote selective formation of isononanoic acid and ester while suppressing catalyst sintering and thermal runaway. Furthermore, the catalyst shows excellent stability without requiring hydrogen pretreatment or additional base. This work establishes defect-healing-induced restructuring as an effective approach to generate stable and highly active catalytic ensembles from labile atomically dispersed precursors and provides fundamental insights into structure–activity relationships governing selective aerobic alcohol oxidation.