Benzyl Alcohol\nValorization via the In Situ Production\nof Reactive Oxygen Species

In this contribution, we outline the efficacy of Pd-based\nbimetallic\ncatalysts toward the oxidative upgrading of benzyl alcohol via the\nin situ synthesis of H<sub>2</sub>O<sub>2</sub> (and related reaction\nintermediates) from the elements. In particular, the formation of\nPdAu and PdFe nanoalloys is observed to be highly effective, offering\nhigh yields of benzaldehyde and near total selectivity to the desired\nproduct, with these catalysts outperforming alternative materials\nreported in the literature. Notably, the PdFe formulation also achieves\nhigh selective utilization of H<sub>2</sub>, a key requirement if\nthe in situ approach to chemical synthesis is to become economically\nviable. Correlative studies, focusing on the direct synthesis of H<sub>2</sub>O<sub>2</sub> and further experiments utilizing preformed\nH<sub>2</sub>O<sub>2</sub>, coupled with Electron Paramagnetic Resonance\n(EPR) spectroscopy indicate that H<sub>2</sub>O<sub>2</sub> itself\nis not primarily responsible for the observed catalysis, but rather,\nthe performance of the PdAu and PdFe formulations can be related to\nthe generation of reactive oxygen species (ROS). While the origin\nof these ROS is not fully understood, it is hypothesized that they\nare generated through a combination of (i) the desorption of reaction\nintermediates formed during H<sub>2</sub>O<sub>2</sub> synthesis and\n(ii) through Fenton-mediated chemistry involving the synthesized H<sub>2</sub>O<sub>2</sub>, in the case of the PdFe-based materials. Importantly,\nour EPR studies also identify the noninnocent nature of the reaction\nsolvent.