Water–Gas Shift Reaction on K/Cu(111) and Cu/K/TiO₂(110) Surfaces: Alkali Promotion of Water Dissociation and Production of H₂

Abstract

The addition of potassium atoms to Cu(111) and Cu/TiO 2 (110) surfaces substantially enhances the rate for water dissociation and the production of hydrogen through the water−gas shift reaction (WGS, CO + H 2 O → H 2 + CO 2 ). In the range of temperatures investigated, 550−625 K, Cu/K/TiO 2 (110) exhibits a WGS activity substantially higher than those of K/Cu(111), Cu(111), and Cu/ZnO(0001̅ ) systems used to model an industrial Cu/ZnO catalyst. The apparent activation energy for the WGS drops from 18 Kcal/mol on Cu(111) to 12 Kcal/mol on K/Cu(111) and 6 Kcal/mol on Cu/K/ TiO 2 (110). The results of density functional calculations show that K adatoms favor the thermochemistry for water dissociation on Cu(111) and Cu/TiO 2 (110) with the cleavage of an O−H bond occurring at room temperature. Furthermore, at the Cu/K/ TiO 2 interface, there is a synergy, and this system has a unique ability to dissociate the water molecule and catalyze hydrogen production through the WGS process. Therefore, when optimizing a regular catalyst, it is essential to consider mainly the effects of an alkali promoter on the metal−oxide interface.

Water Splitting: From Electrode to Green Energy System

“…WGS reaction was a main way for industrial H 2 production [193][194][195][196][197][198][199]. For the traditional WGS reaction, high temperatures and high pressures were essential, and H 2 contamination containing CO 2 , CH 4 and residual CO was inevitable [200][201][202][203][204]. Herein, Bao et al reported a novel electrochemical water-gas shift (EWGS) process for directly producing H 2 with the purity of over 99.99% and the FE of approximately 100% under mild conditions.…”

Application Prospect of K Used for Catalytic Removal of NOx, COx, and VOCs from Industrial Flue Gas: A Review

“…The promotion on the dissociation of H 2 O, the limited process of WGS, can reduce the apparent activation energy and increase the catalytic activity [27]. In addition, K favors the thermochemistry for water dissociation on Cu/TiO 2 with the cleavage of an O-H bond occurring at room temperature [169]. The addition of K on Pt-based catalysts weakens the strength of C-H bond in intermediate formate and promotes the decomposition of intermediate products [170].…”

Photocatalytic Cleavage of β-O-4 Ether Bonds in Lignin over Ni/TiO2

“…Semiconductor, such as TiO 2 , attracted the attention of many researchers due to its versatile advantages involving stable catalytic performance and low cost [28][29][30]. It has been widely reported that the introduction of transition metal [31][32][33] or noble metal nanoparticles [34][35][36] to TiO 2 support is beneficial for electron transfer in the photochemical reaction process. For instance, Farnood et al demonstrated a novel Bi and Pt co-modified TiO 2 catalyst for the photo-oxidation of lignin under solar light for the generation of guaiacol, vanillic acid, vanillin and 4-phenyl-1-buten-4-ol [37].…”