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Site-Dependent Activity and Selectivity of H₂O₂ Formation from H₂ and O₂ over Au-Based Catalysts

Tang, Yanqiang, Zhang, Zhihua, Lu, Mengke, Chen, Bingxu, Fu, Wenzhao, Gan, Jie, Qian, Gang, Duan, Xuezhi, Zhou, Xinggui
Industrial & engineering chemistry process design and development 2019 v.58 no.33 pp. 15119-15126
active sites, catalysts, catalytic activity, chemical bonding, desorption, dissociation, energy, gold, hydrogen, hydrogen peroxide, hydrogenation, oxygen, process design
Fundamental understanding of the structure sensitivity of Au-catalyzed H₂O₂ formation from H₂ with O₂ is of prime scientific and industrial significance. Herein, DFT calculations are employed to reveal the underling nature of the site-dependent H₂O₂ formation activity and selectivity over three typical Au(111), Au(100), and Au(211) sites. The hydrogen dissociation is suggested as the rate-determining step. The structural and charge analysis and the energy barrier decomposition indicate one lower-coordinated edge atom on the Au(211) as the active site for hydrogen dissociation. Furthermore, competition reactions between hydrogenation/desorption of the species involving the O–O bonds and their cleavage are comparatively studied. Au(111) is found to exhibit the highest selectivity to H₂O₂. Finally, a combination of the low-coordinated Au atom with Au(111) is proposed as the catalytically active center of H₂O₂ formation. The results demonstrated here could be valuable for fabricating highly active and selective catalysts for H₂O₂ formation.