[3E01-11] Surface Science / Chemical Property (SS2)

10:45 AM - 11:00 AM JST(1:45 AM - 2:00 AM UTC)

[3E07] CO coadsorption effects on the water–gas shift reaction over Cu clusters on Cu(111): insights from the machine learning force field and microkinetic modeling

*Muhammad Fadhlan Anshor¹, Harry Handoko Halim¹, Yoshitada Morikawa¹ (1. Department of Precision Engineering, Graduate School of Engineering, The University of Osaka (Japan))

CO-induced Cu clustering has been observed experimentally and theoretically, but its catalytic consequences remain unclear. Here, we combine a machine-learning force field, density functional theory, and microkinetic modeling with explicit CO coadsorption to study the water–gas shift reaction on Cu clusters (Cu₇, Cu₄, Cu₃) supported on Cu(111). Because CO binds more strongly to clusters than to Cu(111), clusters sustain higher CO coverages, making coverage-dependent lateral interactions essential for realistic activity predictions. Cu clusters are intrinsically more active than Cu(111) at 450–550 K due to lower H₂O dissociation barriers, the rate-determining step on Cu(111). However, coadsorbed CO suppresses cluster activity at 350–500 K by increasing barriers for H2O dissociation and H₂ recombinative desorption. Including these effects improves agreement with experiment at 450–500 K, while their influence weakens above 550 K as CO coverage decreases. Overall, CO coadsorption and cluster size jointly reshape WGSR activity trends under realistic conditions.

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