Electrocatalytic reduction of CO2 to formate has become one way to increase the value of CO2 and to overcome the climate change issue. Novel catalysts for the critical role of enhancing reaction selectivity have been continuously explored to provide the best performance. Lately, composite materials have drawn much attention because the synergistic effect between the components provides enhanced physical and chemical properties. Here, we present a highly efficient CO2 reduction reaction to formate on a tin­(IV) oxide/zinc oxide (SnO2/ZnO) composite electrocatalyst with a grainy hollow nanofiber (HNF) structure. The faradaic efficiency (FE) of formate on the SnO2/ZnO composite HNF reaches as high as 97.9% at −1.34 V vs reversible hydrogen electrode (RHE), outperforming many tin-based catalysts. At −1.54 V (vs RHE), the SnO2/ZnO HNF exhibits 2 times and 4 times higher current density for formate generation than those of SnO2 HNF and nanoparticles (NPs), respectively. This superior catalytic performance is attributed to its one-dimensional continuous structure as well as to the synergistic effects between SnO2 and ZnO, which facilitate faster electron transfer and improve the conductivity of SnO2/ZnO composite HNF.

The CO 2 atmospheric concentration level hit the record at more than 400 ppm and is predicted to keep increasing as the dependence on fossil fuels is inevitable. The CO 2 electrocatalytic conversion becomes an alternative due to its environmental and energy-friendly properties and benign operation condition. Lately, bimetallic materials have drawn significant interest as electrocatalysts due to their distinct properties, which the parents' metal cannot mimic. Herein, the indium−bismuth nanosphere (In 16 Bi 84 NS) was fabricated via the facile liquid-polyol technique. The In 16 Bi 84 NS exhibits exceptional performance for CO 2 reduction to formate, with the faradaic efficiency (FE) approaching ∼100% and a corresponding partial current density of 14.1 mA cm −2 at −0.94 V [vs the reversible hydrogen electrode (RHE)]. Furthermore, the FE could be maintained above 90% in a wide potential window (−0.84 to −1.54 V vs the RHE). This superior performance is attributed to the tuned electronic properties induced by the synergistic interaction between In and Bi, enabling the intermediates to be stably adsorbed on the catalyst surface to generate more formate ions.

No abstract

The electrochemical CO 2 reduction reaction (CO 2 RR) to form C 2+ products was investigated to obtain high selectivity in liquid CO 2 -fed systems having the limitation of low current density. Over the past decade, flow cells with gas diffusion electrodes (GDEs) have emerged to achieve high current densities close to the industrial-relevance scale by overcoming gas diffusion limitations. However, key parameters of GDE design, including binders, were not sufficiently identified to enhance selectivity and current density for C 2+ products. Nafion, FAA-3, and polypyrrole were used to explore the effects of binder type and content on GDE properties such as porosity (gas permeability), ion conductivity, and electron conductivity for the modulation of the CO 2 RR on the Cu 2 O catalyst. The Cu 2 O GDEs with high binder content showed poor selectivity for C 2+ products because of their low exposure to the catalyst surface and decreased gas permeability. The anion exchange ionomer, FAA-3, showed high selectivity for C 2+ products and electrode stability resulting from the C−C coupling increase and suppression of the hydrogen evolution reaction, which was induced by OH − conductivity. In contrast, the cation exchange ionomer, Nafion, exhibited low electrode stability due to the loss of gas products through the catholyte and due to its excessive wettability.

No abstract