NO Binding Energies to and Diffusion Barrier on Pd Obtained with Velocity-Resolved Kinetics.

Dmitriy Borodin,Georgios Skoulatakis,Stefan Hörandl,Alec M Wodtke,Michael Schwarzer,Dirk Schwarzer,Jan Fingerhut,Theofanis N Kitsopoulos,Igor Rahinov

doi:10.1021/acs.jpcc.1c02965

Abstract

We report nitric oxide (NO) desorption rates from Pd(111) and Pd(332) surfaces measured with velocity-resolved kinetics. The desorption rates at the surface temperatures from 620 to 800 K span more than 3 orders of magnitude, and competing processes, like dissociation, are absent. Applying transition state theory (TST) to model experimental data leads to the NO binding energy E0 = 1.766 ± 0.024 eV and diffusion barrier DT = 0.29 ± 0.11 eV on the (111) terrace and the stabilization energy for (110)-steps ΔEST = 0.060–0.030+0.015 eV. These parameters provide valuable benchmarks for theory.

Highlights

Binding energies of molecules at surfaces serve as important descriptors, for screening heterogeneous catalysts
The screening is done using electronic structure calculations based on density functional theory (DFT) with the generalized gradient approximation (GGA).[3−5] DFT-GGA often yields results in agreement with experimental binding energies,[3] there are examples where it fails
We have reported experimental desorption rates of nitric oxide from Pd(111) and Pd(332) between 620 and 800 K

Summary

Introduction

Binding energies of molecules at surfaces serve as important descriptors, for screening heterogeneous catalysts. Exchange-correlation functionals at the GGA level predict CO to be bound at the 3-fold hollow site of Pt(111); CO binds to the top site. This system has been tackled by various theoreticians, and improvements have been developed,[7−9] concluding that GGA-related overbinding errors are enhanced at sites with high coordination

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Results

Discussion

Conclusion