posted on 2024-02-06, 04:14authored byMuhammed Yusufoğlu, Saeede Tafazoli, Hadi Jahangiri, M. Barış Yağcı, Timuçin Balkan, Sarp Kaya
The electrochemical CO2 reduction reaction
(CO2RR) holds tremendous promise as a strategy for lowering
atmospheric
CO2 levels and creating new clean energy sources. The conversion
of CO2RR 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 CuxO overlayers prepared by atomic layer deposition
(ALD). CuxO significantly enhanced CO
selectivity, and 88% CO selectivity at a relatively low potential
of −0.8 V was obtained on an optimized CuxO overlayer thickness (CuxO-250/ZnO).
The addition of CuxO on ZnO was found
to dramatically increase the electrochemical surface area (ESCA),
lower the charge-transfer resistance (Rct), and introduce new active sites in the ε-CuZn4 phase. Furthermore, electrochemical Raman spectroscopy results showed
that the CuxO-250/ALD electrode developed
a ZnO layer on the surface during the CO2RR, while the
bare ZnO electrode showed no evidence of ZnO during the reaction.
These results suggest that the addition of CuxO by ALD played a crucial role in stabilizing ZnO on the surface.
The initial amount of CuxO 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-CuZn4 and ZnO that developed during the CO2RR. Overall, our
study provides new insights into the dynamic behavior and surface
composition of CuZn electrocatalysts during CO2RR.