Constructing Highly Efficient ZnO Nanocatalysts with Exposed Extraordinary (110) Facet for CO₂ Electroreduction

Abstract

Electrochemical reduction of CO 2 to highly valuable products is a promising way to reduce CO 2 emissions. The shape and facets of metal nanocatalysts are the key parameters in determining the catalytic performance. However, the exposed crystal facets of ZnO with different morphologies and which facets achieve a high performance for CO 2 reduction are still controversial. Here, we systematically investigate the effect of the facetdependent reactivity of reduction of CO 2 to CO on ZnO (nanowire, nanosheet, and flower-like). The ZnO nanosheet with exposed (110) facet exhibited prominent catalytic performance with a Faradaic efficiency of CO up to 84% and a current density of −10 mA cm −2 at −1.2 V versus RHE, far outperforming the ZnO nanowire ( 101) and ZnO nanoflower (103). Based on detailed characterizations and kinetic analysis, the ZnO nanosheet (110) with porous architecture increased the exposure of active sites. Further studies revealed that the high CO selectivity originated from the enhancement of CO 2 adsorption and activation on the ZnO (110) facet, which promoted the conversion of CO 2 toward CO. This study provides a new way to tailor the activity and selectivity of metal catalysts by engineering exposed specific facets.

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

“…It is established that the OCHO* species transforms into formate through the capture of one electron, OCHO* + e – → HCOO – . − In this study, the FE for this formate process reached 20%. The HOOC* species is also known to convert into *CO via the reaction HOOC* + H + + e – → *CO + H 2 O. − Subsequently, *CO desorbs as free gaseous CO, which was a major product in this study with an FE exceeding 15%. Zn-based electrodes are recognized for their high FEs for CO. − These two primary C 1 reduction products are straightforward two-electron processes and were formed over Zn/Cu and Zn/CuZn electrodes.…”

“…The HOOC* species is also known to convert into *CO via the reaction HOOC* + H + + e – → *CO + H 2 O. − Subsequently, *CO desorbs as free gaseous CO, which was a major product in this study with an FE exceeding 15%. Zn-based electrodes are recognized for their high FEs for CO. − These two primary C 1 reduction products are straightforward two-electron processes and were formed over Zn/Cu and Zn/CuZn electrodes. Under more negative potentials and high electrolyte conditions, CH 4 was detected with an FE above 15%, indicating that *CO underwent hydrogenation to form hydrocarbons.…”

“…In contrast, catalysts based on other metals generally offer fewer options for reduction products. For instance, zinc catalysts are commonly used for CO reduction, − while certain materials like p-block elements are utilized for formate production. − …”