Hu Yongke,Xia Jiawei,Li Jin,Li Huaju,Li Yanxing,Li Shaozhong,Duanmu Chuansong,Li Bindong,Wang Xin
A highly efficient nitrogen-doped carbon black (NCB)-supported PdBi alloy nanocatalyst has been fabricated via a facile coreduction wet chemical approach. The optimal PdBi/NCB shows outstanding catalytic performance with broad substrate scope, good functional group tolerance towards direct oxidative esterification of alcohols under mild conditions in a heterogeneous catalytic system with air as the sole oxidant. A variety of benzylic and allylic alcohols were smoothly reacted with methanol and even with long-chain aliphatic alcohols, providing desired esters in good to excellent yields. Moreover, the as-prepared catalyst is easily recycled and can be reused at least five times without a significant loss of catalytic activity. Superior catalytic activity is mainly attributable to the unique structure of the catalyst, including synergetic electronic effect between Pd and Bi, as well as modulated surface character by acidification and N doping for better active components’ anchoring and dispersion, as well as reactants’ adsorption. This study provides a facial, practical, eco-friendly and efficient catalytic system for oxidative esterification of alcohols and shows promising prospect in industrial production.
The morphology and compositional modulation of palladium-based nanomaterials are of paramount importance in enhancing the catalytic performance of the ethanol oxidation reaction (EOR). In this study, we employed a simple oil bath method to synthesize PdBi alloy nanoparticles (NPs), maintaining the same elemental ratio. The size of the NPs could be modulated by varying the surfactant dosage. The synthesized PdBi alloys exhibited alterations in the d-band center of Pd, which were attributed to strain and ligand effects. These alterations subsequently affected the adsorption energy of the catalyst surface for the reaction intermediates. The current density of the Pd9Bi/200 NP in the ethanol oxidation reaction was found to be as high as 1042.0 mA mg–1, which is approximately twice that of Pd/C (508.0 mA mg–1). This enhanced activity can be attributed to the modification of the electronic structure and morphology, which enables the material to possess a larger electrochemically active surface area (ESCA), thus providing a substantial number of active sites for the catalytic reaction. Furthermore, the experimental data indicated that increasing the electrocatalytic temperature, pH, and ethanol concentration could accelerate the electrooxidation rate of the EOR. This study presents an effective approach for investigating the role of surfactants in the synthesis of nanomaterials and enhancing the activity and stability of noble metal catalysts.
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