Establishing and Understanding Adsorption–Energy Scaling Relations with Negative Slopes

Abstract

Adsorption-energy scaling relations are widely used for the design of catalytic materials. To date, only linear scaling relations are known in which the slopes are positive. Considering the adsorption energies of F, O, N, C, and B on transition metals, we show here that scaling relations with negative slopes also exist between certain adsorbates. The origin of such unconventional scaling relations is analyzed in terms of common descriptors such as d-band center, work function, number of outer electrons, electronic charge on the adsorbates, integrated crystal orbital overlap populations, and crystal orbital Hamilton populations. Conventional scaling relations are formed between adsorbates such as F, O, N, and C, which create ionic-like bonds with surfaces. Conversely, anomalous scaling relations are established between those and covalently bound adsorbates such as B. This widens the theory of adsorption-energy scaling relations and opens new avenues in physical chemistry and catalysis, for instance, in direct borohydride fuel cells.

Revealing the nature of active sites in electrocatalysis

“…In practice, D may be a simple descriptor such as the number of valence electrons of the metal atoms at the adsorption sites, 45,47,48 work functions, electronic charges on the adsorbates, d-band centers, or a more sophisticated descriptor such as the crystal orbital overlap population (coop) or the crystal orbital Hamilton population. 49 As shown in Fig. 1, the offset b depends on the value of the slope: 46,50 if m s 1, the offset is proportional to the coordination of the adsorption sites.…”

“…Conventional scaling relations are formed between electronegative adsorbates such as F, O, N, and C. Conversely, anomalous scaling relations with negative slopes are established between those and less electronegative adsorbates such as B. 49 The downside of scaling relations is that they allegedly limit the efficiency of electrocatalysts. For instance, the scaling relation between *OOH vs. *OH is thought to limit the oxygen evolution and reduction reactions (OER, ORR): while the energetic separation of those intermediates should ideally be 2.46 eV, on most catalysts it is $3.20 eV.…”

First-Principles microkinetic study of methanol synthesis on Cu(221) and ZnCu(221) surfaces

“…Based on many common electronic structure descriptors, such as lower d-band center and less charge transferred, etc. can lead to lower bond strength [39]. The discussion about the role of Zn can also be found in recent study by Liao et al [40].…”

Electrostatic Origins of Linear Scaling Relationships at Bifunctional Metal/Oxide Interfaces: A Case Study of Au Nanoparticles on Doped MgO Substrates

“…Recent efforts in this direction include breaking linear scaling relations at doped sulfur edges of MoS 2 for CO 2 electroreduction [17] and LiH mediation on transition metals in lowtemperature ammonia synthesis. [19,20] One class of catalytic active sites that is prevalent in heterogeneous catalysis,b ut for which the physics and even existence of scaling relationships are essentially unknown, consists of sites at the interface between metal nanoparticles and oxide supports. [19,20] One class of catalytic active sites that is prevalent in heterogeneous catalysis,b ut for which the physics and even existence of scaling relationships are essentially unknown, consists of sites at the interface between metal nanoparticles and oxide supports.…”