(3k) Preserving the Exposed Facets Reveals the Higher Activity of Disordered Pt3sn Nanocubes Towards Electro-Reduction and Oxidation Reactions Compared to Ordered Counterparts

Ordered alloys have been demonstrated to catalyze electrochemical reactions with better stability and activity when compared to their disordered counterparts.¹ However, the exposed facets of these alloy can be easily altered in the process of disordered to ordered phase transition upon annealing at several hundred centigrade,² and hence it is challenging to differentiate the effect of structural ordering from the effect of surface faceting, which has been recognized as one of the crucial factors governing the activity of metal catalysts.³ In this work we reveal that by using the high mobility of Sn, partial phase transition can be achieved at relatively low temperature, which prevents the evolution of the exposed facets.⁴ We further reveal that when the {100} facets are maintained, the 60% ordered Pt₃Sn nanocubes outperform the 95% ordered Pt₃Sn nanocubes, achieving 2-fold and 5-fold of specific activity towards oxygen reduction and methanol oxidation, respectively. We discover by XANES analysis as well as benchmarking with the activity of pure Pt nanocubes that electronic effect is minimal, and the degree of defect formation and metal oxidation under working conditions varies with different degree of ordering, which is likely to be the cause of the higher activities of the more disordered nanocubes.

Reference

(1) Gamler, J. T. L.; Ashberry, H. M.; Skrabalak, S. E.; Koczkur, K. M. Random Alloyed versus Intermetallic Nanoparticles: A Comparison of Electrocatalytic Performance. Adv. Mater. 2018, 30 (40), 357–364.

(2) Li, Q.; Wu, L.; Wu, G.; Su, D.; Lv, H.; Zhang, S.; Zhu, W.; Casimir, A.; Zhu, H.; Mendoza-Garcia, A.; et al. New Approach to Fully Ordered Fct-FePt Nanoparticles for Much Enhanced Electrocatalysis in Acid. Nano Lett. 2015, 15 (4), 2468–2473.

(3) Jin, M.; Zhang, H.; Xie, Z.; Xia, Y. Palladium Nanocrystals Enclosed by {100} and {111} Facets in Controlled Proportions and Their Catalytic Activities for Formic Acid Oxidation. Energy Environ. Sci. 2012, 5 (4), 6352–6357.

(4) Chen, H. S.; Benedetti, T. M.; Goncales, V. R.; Bedford, N. M.; Scott, R. W. J.; Webster, R. F.; Cheong, S.; Gooding, J. J.; Tilley, R. D. Preserving the Exposed Facets of Pt3Sn Intermetallic Nanocubes during an Order to Disorder Transition Allows the Elucidation of the Effect of the Degree of Alloy Ordering on Electrocatalysis. J. Am. Chem. Soc. 2020, 142(6),3231-3239

Research Interests

• Catalysis for renewable energy production and utilization
• Design, synthesis and characterization of semiconductor and metal nanomaterials with well-defined and facet-specific interfaces
• Mechanistic study of reaction pathways and charge transfer on well-defined inorganic interfaces