Role of Surface Oxophilicity in Copper-Catalyzed Water Dissociation

Abstract

Understanding water dissociation on nonprecious metal surfaces is essential toward designing efficient catalysts for important chemical reactions such as water-splitting and carbon dioxide reduction. Hydrogen binding energy (HBE) has been proposed to be a good descriptor to predict hydrogen evolution reaction (HER) activity in alkaline electrolytes. In this work, we showed that although HBE values could predict the HER activity reasonably well, the oxophilicity of the catalyst surface also played a significant role in water dissociation. To elucidate the role of surface oxophilicity, a series of nonprecious copper-based bimetallic materials were systematically studied for HER activity in alkaline conditions. By alloying copper with small amounts of oxophilic transition metals such as Ti, Co, or Ni, a significant enhancement in HER activity was achieved in comparison to pure copper. However, if the HBE was considered as the sole descriptor, the experimentally measured HER activity trend did not match the theoretical trend as predicted by density functional theory (DFT) calculations. Further studies combining both computational efforts and experimental investigation of metal oxide/hydroxide (MO/OH) clusters deposited on Cu surfaces showed that oxygen binding energies (i.e., the oxophilicity of the dopant metal) together with HBEs should be used as descriptors to predict HER activity in alkaline conditions due to the synergistic interactions between copper and the oxophilic metal.

Formation of carbon–nitrogen bonds in carbon monoxide electrolysis

“…Taking these energies as an input of the kinetic model, we predict the current density as shown in the Supplementary Figure 15, from which we estimated an overpotential of HER of ~0.4 V, consistent with the experiment. 6 Supplementary Figure 15: The current density of HER predicted from the kinetic model. 7…”

Synergistic Electrocatalysts for Alkaline Hydrogen Oxidation and Evolution Reactions

“…Introducing oxophilic metal elements to tailoring the adsorption energy of the OH ad intermediate thus modulating the kinetics of the Volmer step while preserving the high activity of hosts towards the Tafel or Heyrovsky step are more common strategies to boost the alkaline HER performance. [136] Kim et al calculated the change of the OH ad binding energies after incorporating a series of exophilic transition metal elements onto the metallic Ni surface. [129] The calculation model was shown in Figure 13e.…”

Synergistic Cascade Hydrogen Evolution Boosting via Integrating Surface Oxophilicity Modification with Carbon Layer Confinement

“…[ 6 ] Very recently, it was reported that HER activity of copper was significantly enhanced via doping with small amounts of oxophilic transition metals. [ 7 ] The promoted HER performance was mainly ascribed to the interaction between oxophilic component and oxygen atom of water molecule. Meanwhile, Kim et al.…”