ALD-Engineered Cu_xO Overlayers Transform ZnO Nanorods for Selective Production of CO in Electrochemical CO₂ Reduction

Abstract

The electrochemical CO 2 reduction reaction (CO 2 RR) holds tremendous promise as a strategy for lowering atmospheric CO 2 levels and creating new clean energy sources. The conversion of CO 2 RR to CO, in particular, has garnered significant scientific interest due to its industrial feasibility. Within this context, the CuZn-based electrocatalyst presents an attractive alternative to conventional CO-selective electrocatalysts, which are often costly and scarce. Nevertheless, the wide-range utilization of CuZn electrocatalysts requires a more comprehensive understanding of their performance and characteristics. In this study, we synthesized ZnO nanorods through electrodeposition and subsequently coated them with Cu x O overlayers prepared by atomic layer deposition (ALD). Cu x O significantly enhanced CO selectivity, and 88% CO selectivity at a relatively low potential of −0.8 V was obtained on an optimized Cu x O overlayer thickness (Cu x O-250/ZnO). The addition of Cu x O on ZnO was found to dramatically increase the electrochemical surface area (ESCA), lower the charge-transfer resistance (R ct ), and introduce new active sites in the ε-CuZn 4 phase. Furthermore, electrochemical Raman spectroscopy results showed that the Cu x O-250/ALD electrode developed a ZnO layer on the surface during the CO 2 RR, while the bare ZnO electrode showed no evidence of ZnO during the reaction. These results suggest that the addition of Cu x O by ALD played a crucial role in stabilizing ZnO on the surface. The initial amount of Cu x O was shown to further affect the redeposition of the ZnO layer and hence affect the final composition of the surface. We attribute the improvement in CO selectivity to the introduction of both ε-CuZn 4 and ZnO that developed during the CO 2 RR. Overall, our study provides new insights into the dynamic behavior and surface composition of CuZn electrocatalysts during CO 2 RR.

Customized CO2 electroreduction to methane or ethylene by manipulating *H and *CO adsorption on Cu/CeOx catalysts

“…3a, were deconvoluted into eight peaks corresponding to Ce 3d 5/2 (v, 882.4 eV; v′,884.9 eV; v′′, 888.7 eV; v′′′, 898.2 eV) and Ce 3d 3/2 states (μ, 900.8 eV; μ′, 903.5 eV; μ′′, 907.2 eV; μ′′′, 916.6 eV). 36,37 Peaks designated v, v′′, v′′′, μ, μ′′, and μ′′′ are indicative of Ce 4+ species, while the v′ and μ′ peaks are attributed to Ce 3+ species, denoting the coexistence of Ce 4+ and Ce 3+ within the composite matrix. 38 The relative abundance of Ce 3+ to total cerium species was quantitatively assessed and was summarized in Table S1 †.…”

Electrocatalytic CO2 Reduction for Dynamic C1, C2, and C3+ Chemistry over Electrodeposited Zn on Cu and CuZn Mesh Supports

“…Numerous studies have utilized copper as a foundational material to develop Cu-based compounds, aiming to enhance the reduction properties of pure Cu through advanced surface modifications . Among various Cu-based bimetals, the combination of Cu and Zn has been synthesized using a variety of methods to explore new EC CO 2 reduction characteristics. − These fabrication techniques have unveiled a range of properties and high selectivity for products such as formate, CO, CH 4 , C 2 H 4 , and ethanol. Notably, electrodeposition has emerged as a prominent and straightforward method for fine-tuning the properties of overlayer metals. − Meng et al utilized potential step electrodeposition to create a Cu/Zn bimetal catalyst, achieving a Faradaic efficiency (FE) of 40.2% for C 2 H 4 .…”