# Harnessing work-function-driven rotational steering for quantum state control in HCl dissociation on bimetallic alloys

## TL;DR

This paper shows how rotational energy can be used to control chemical reactions on bimetallic surfaces by leveraging differences in work functions.

## Contribution

The study introduces a new design principle for catalysts based on work function differences and surface strain to control reactivity.

## Key findings

- Rotational enhancement efficacies of 225 and 56 were observed on Ag/Pt(111) and Cu/Pt(111) surfaces.
- Rotational efficacy scales with work function difference and is modulated by surface strain.
- Rotational effects depend on the global topography of the potential energy surface, not just the transition state.

## Abstract

The dissociative chemisorption of heteronuclear molecules is a cornerstone of heterogeneous catalysis. However, the ability to predict and control how rotational excitation governs reactivity has remained a fundamental challenge, lagging far behind the established understanding of vibrational effects. Here, through six-dimensional quantum dynamics simulations of HCl dissociation on bimetallic surfaces, we report unprecedented rotational enhancement, with efficacies reaching roughly 225 and 56 on Ag/Pt(111) and Cu/Pt(111), respectively. This dramatic effect originates from interfacial charge transfer driven by work function differences between the substrate and the supported metal monolayer (Φsub > Φsup), which generates a non-monotonic orientation-dependent potential energy landscape. We further establish a quantitative, predictive design principle, where rotational efficacy scales primarily with the work function difference and is systematically modulated by surface strain, with the highest efficacy achieved when a large work function difference is combined with compressive strain. This multivariate framework resolves a long standing dichotomy by demonstrating that rotational effects depend decisively on the global topography of the potential energy surface (PES), a mechanism fundamentally distinct from the transition state (TS) localized picture of vibrational promotion. The resulting quantum state control window enables rotation to act as a precise external knob for steering reactivity, advancing a new paradigm for the design of catalysts with targeted, state selective function.

The dissociative chemisorption of heteronuclear molecules is a cornerstone of heterogeneous catalysis.