The ABC of Generalized Coordination Numbers and Their Use as a Descriptor in Electrocatalysis

Abstract

The quest for enhanced electrocatalysts can be boosted by descriptor‐based analyses. Because adsorption energies are the most common descriptors, electrocatalyst design is largely based on brute‐force routines that comb materials databases until an energetic criterion is verified. In this review, it is shown that an alternative is provided by generalized coordination numbers (denoted by CN¯$\overline {{\rm{CN}}} $ or GCN), an inexpensive geometric descriptor for strained and unstrained transition metals and some alloys. CN¯$\overline {{\rm{CN}}} $ captures trends in adsorption energies on both extended surfaces and nanoparticles and is used to elaborate structure‐sensitive electrocatalytic activity plots and selectivity maps. Importantly, CN¯$\overline {{\rm{CN}}} $ outlines the geometric configuration of the active sites, thereby enabling an atom‐by‐atom design, which is not possible using energetic descriptors. Specific examples for various adsorbates (e.g., *OH, *OOH, *CO, and *H), metals (e.g., Pt and Cu), and electrocatalytic reactions (e.g., O2 reduction, H2 evolution, CO oxidation, and reduction) are presented, and comparisons are made against other descriptors.

Gas-phase errors in computational electrocatalysis: a review

“…Scaling relations can be used to build Sabatier-type volcano plots, which are extensively used to display the trends in electrocatalytic activity of materials as a function of a given descriptor or a combination of them. 1,11,71,88,91,92 These plots also establish the conditions for optimal catalysis, found at the top of the volcano, and have led to the discovery of promising electrocatalysts for important reactions. 2,76,92,93…”

A structure-sensitive descriptor for the design of active sites on MoS2catalysts

“…For instance, conventional and “generalized” coordination numbers capture the trends in adsorption energy on extended surfaces and nanoparticles of Pt, Au, Cu and Zn. 6,44–50 In fact, there is an analytic relationship between coordination numbers and ε d , 6 and a linear proportionality between ε d and Δ E Ads by virtue of the d-band model. 1…”

Impact of Pt(hkl) Electrode Surface Structure on the Electrical Double Layer Capacitance

“…All potentials used in this study were referred to the reversible hydrogen electrode (RHE). Parametrization of the Pt­( hkl ) surfaces was done using the generalized coordination number (GCN) , approach (see Supporting Information (SI), Figure S1), similar to our previous study …”