Structure Dependent Product Selectivity for CO₂ Electroreduction on ZnO Derived Catalysts

Abstract

Electrochemical conversion of CO 2 is an attractive alternative to releasing it to the atmosphere. Catalysts derived from electroreduction of metal oxides are often more active than when starting with metallic phase catalyst. The origin of this effect is not yet clear. Using ZnO nanorods, we show that the initial structure of the oxide as well as the electrolyte medium have a profound impact on the structure of the catalytic active Zn phase, and thereby the selectivity of the catalysts. ZnO nanorods with various aspect ratios were electrochemically reduced in different electrolytes leading to metallic Zn with different structures; a sponge-like structure, nanorods and nanoplates. The sponge-like Zn produced syngas with H 2 : CO = 2, and some formate, the nanorods produced only syngas with H 2 : CO = 1, while Zn nanoplates exhibited 85 % selectivity towards CO. These results open a pathway to design new electrocatalysts with optimized properties by modifying the structure of the starting material and the electroreduction medium.

Transparent Porous ZnO|Metal Complex Nanostructured Materials: Application to Electrocatalytic CO2 Reduction

“…Currently, a variety of earth-abundant metal-based molecular catalysts have been identified, reporting high selectivity for the CO 2 reduction reaction. ,− Among examples, cobalt phthalocyanine has been identified as a good electrocatalyst for CO 2 RR owing to its high selectivity and activity for CO production. , Besides, oxide-derived metal-based materials such as CuO, Cu 2 O, − Ag 2 O, , NiO, , and TiO 2 − have been successfully demonstrated to be active and selective catalysts for CO 2 reduction. ZnO, a low toxic compound, is an oxide-derived non-noble metal with promising optical, electronic, photovoltaic, − and catalytic properties. − Recently, a maximum faradaic efficiency (FE) of 92% for CO 2 to CO conversion has been reported for a nanoporous (NP) ZnO . However, the catalytic system suffered from degradation issues due to morphological changes during CO 2 reduction in aqueous media.…”

Zn-Based Catalysts for Selective and Stable Electrochemical CO2Reduction at High Current Densities

“…The oxidederived Zn (OD-Zn) emerged as a catalytically active material, owing to its increased active surface area and grain boundary concentration. 27,28 Apart from its pristine metallic form, Zn exhibited remarkable ECR performance in sulfide 29 (ZnS 2 ) and oxide 30 interest not only for its ECR performance but also for its ability to act as an active catalyst substrate for various (catalytically active) d-block metals. 31 While much research has been devoted to improving the performance of such Zn-based catalysts, most of these studies performed ECR in aqueous (H-cell) systems where the current densities are limited to below 50 mA cm −2 .…”

“…Luo et al demonstrated a high-performance Zn cathode by creating an active Zn-foam, exploiting its high surface-area. The oxide-derived Zn (OD-Zn) emerged as a catalytically active material, owing to its increased active surface area and grain boundary concentration. , Apart from its pristine metallic form, Zn exhibited remarkable ECR performance in sulfide (ZnS 2 ) and oxide (ZnO) structures. The latter has attracted further interest not only for its ECR performance but also for its ability to act as an active catalyst substrate for various (catalytically active) d-block metals …”

Efficient Electrochemical Reduction of CO2 to CO in Ionic Liquids

“…Converting CO 2 into useful products is considered as an important way towards CO 2 utilization. [2] An important conversion process is the reduction of CO 2 to CO. The product CO is promising as the main reactant of Fischer-Tropsch process .…”

“…[15] At present, the above problems have been overcome by the use of IL with 1,2,4-triazole as anion. [7,15] The anion is able to chemically bind CO 2 absorption capacity and is easy to be synthesized. [18] And the important feature of the […”