Electrochemical reduction of carbon monoxide (CO) has recently been emerging as a potential alternative for converting carbon emission into high-value multi-carbon products such as acetate. Nonetheless, the activity and selectivity for producing acetate have remained low. Herein, we developed an atomically ordered copper-palladium intermetallic compound (CuPd-IC) structure that achieved a high Faradaic e ciency of 70 ± 5% for CO-to-acetate production with a partial current density of 425 mA•cm − 2 . This corresponded to an acetate production rate of 4.0 mmol•h − 1 •cm − 2 , and 5.3 times of enhancement in acetate production compared to pure Cu. Structural characterizations and density functional theory calculations suggested that CuPd-IC presents a high density of Cu-Pd pairs that act as the active sites to enrich the surface CO coverage, stabilize the surface ethenone as a key acetate-path intermediate, and inhibit hydrogen evolution reaction, thus promoting acetate formation. Using a membrane electrode assembly device, the CuPd-IC catalyst enabled 100 hours of CO-to-acetate operation at 500 mA•cm − 2 and an average acetate Faradaic e ciency of 43%, producing ~ 2 mol acetate.

Microkinetic analysis plays an important role in catalyst design. Although Langmuirian microkinetics is widely used, surface kinetics is actually non-Langmuirian, which depends on the surface nonuniformity caused by either the adsorbate−adsorbate interactions or various types of active sites exposed on the surfaces. Herein we proposed an approach based on the maximum rate analysis for an accurate and efficient analysis of surface kinetics, where the details of the surface nonuniformity were incorporated into the apparent rate coefficients. The present approach was verified by using the water-gas shift reaction on Cu(111) surfaces as a case study. Furthermore, a formulation of free energy landscape (FEL) was proposed to provide a general and intuitive picture of the catalytic reaction network, which was used to understand how surface coverages could affect the values of the macroscopic measurables. Our results demonstrated that even a mild coverage effect, which changed the overall rate only slightly, could significantly change the values of the macroscopic measurables, such as the reaction orders and the apparent activation energies. These were mainly due to the fact that even a mild coverage effect could change the rate-determining steps and weaken the binding strength of some key intermediates. Our results highlight the importance of the coverage-dependent microkinetic analysis aided by the present formulation FEL, which offers a useful tool to bridge theory and experiment and to reveal the in situ nature of the active sites, the rate-determining steps, and the key intermediates, which in turn are beneficial to the rational design of catalysts.

Heterogeneous catalysts often work under high pressure with high surface coverage, which can markedly affect their catalytic performances. Herein, we propose a protocol for an operando theoretical analysis to explore, accurately and efficiently, the on-site dynamics of the adlayer using syngas conversion on Rh(111) surfaces as an example. While it is often emphasized that coadsorbates influence the intermediate reactivity greatly, our work demonstrates here that the intermediate can induce a local environment that is optimal to itself so as to optimize the reaction paths. The commonly used mean-field models fail to account for this dynamic and intermediate-specific local coverage change and thus fail to reproduce the experimental observations on the pressure-dependent selectivity changes. The present study provides new insights into how local surface coverage tunes the catalysis, highlighting the importance of the operando theoretical analysis in understanding the catalytic phenomena and providing a powerful tool for rational design of catalysts.