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On the nature of Pt-carbon interactions for enhanced hydrogen generation

Chen, Wenyao, Chen, Shuangming, Qian, Gang, Song, Li, Chen, De, Zhou, Xinggui, Duan, Xuezhi
Journal of catalysis 2020 v.389 pp. 492-501
ammonia, carbon, catalysts, catalytic activity, electron transfer, energy, engineering, hydrogen, hydrogen production, hydrolysis, platinum
Understanding the metal-support interactions in heterogeneous catalysis is critical yet complicated to tailor-design the catalysts with desirable properties. Exemplified with Pt-catalyzed ammonia borane (AB) hydrolysis, a dramatic increase of 20 folds in the catalytic activity is achieved by engineering the Pt-carbon interactions via adopting four different carbon materials (AC, CNT, f-CNF and p-CNF) as the catalyst supports. Multiple characterization techniques reveal that the Pt-carbon electronic interactions, including electron transfer and interfacial bonding, are deemed to be mainly responsible for the remarkable enhancement in the hydrogen generation rate. The molar ratio of electron-withdrawing group to electron-donating group (nEWG/nEDG) is further identified as a descriptor of catalyst in terms of Pt binding energy, which exhibits an almost linear relationship with the catalytic activity. Moreover, a comparison of Pt catalyst pre-treatments, i.e., H₂ and AB reduction as well as Ar calcination, suggests that the Pt-O-C linkages within the Pt-carbon interactions are highly stable yet inferior to this reaction. As a result, combining the merits of the highest Pt binding energy as well as the minimum Pt-O-C linkages, the Pt/p-CNF delivers the highest catalytic activity. The insights presented here could shed new lights on the nature of Pt-carbon interactions, which could be extended to the design and manipulation of other metal-carbon catalysts.