Quasi-square-shaped cadmium hydroxide nanocatalysts for electrochemical CO2 reduction with high efficiency.

Chunjun Chen,Yahui Wu,Longfei Lin,Ruizhi Wu,Shoujie Liu,Qinggong Zhu,Honglei Fan,Jingyuan Ma,Yuying Huang,Xiaofu Sun,Xupeng Yan,Buxing Han,Minqiang Hou,Zhaofu Zhang,Jun Ma

doi:10.1039/d1sc02328d

Abstract

Powered by a renewable electricity source, electrochemical CO2 reduction reaction is a promising solution to facilitate the carbon balance. However, it is still a challenge to achieve a desired product with commercial current density and high efficiency. Herein we designed quasi-square-shaped cadmium hydroxide nanocatalysts for CO2 electroreduction to CO. It was discovered that the catalyst is very active and selective for the reaction. The current density could be as high as 200 mA cm−2 with a nearly 100% selectivity in a commonly used H-type cell using the ionic liquid-based electrolyte. In addition, the faradaic efficiency of CO could reach 90% at a very low overpotential of 100 mV. Density functional theory studies and control experiments reveal that the outstanding performance of the catalyst was attributed to its unique structure. It not only provides low Cd–O coordination, but also exposes high activity (002) facet, which requires lower energy for the formation of CO. Besides, the high concentration of CO can be achieved from the low concentration CO2via an adsorption-electrolysis device.

Highlights

Ray absorption spectroscopy (XAS) and density functional theory (DFT) calculations showed that high activity facet (002) exposed on the surface and the low Cd–O coordination number resulted in the enhancement of CO2 activation
From transmission electron microscope (TEM) image of cadmium hydroxide (Cdhy)-QS (Fig. 1A), we can observe that the Cdhy was dispersed homogeneously on the cross-linked architecture of tannic acid (TA)
We have demonstrated that Cdhy-QS has highly reactive facet on the surface with low Cd–O coordination number, resulting in very high efficiency for CO2 electroreduction to CO

Summary

Introduction

The concentration of atmospheric carbon dioxide (CO2) increased dramatically with the consumption of fossil fuels, which has caused climate change and serious environmental issues.[1,2,3,4,5] Electrochemical CO2 reduction reaction (CO2RR) is a promising solution to facilitate the carbon balance, which can transfer CO2 into valuable fuels and chemicals, and provide a solution for storage of the renewable energy.[6,7,8,9,10] CO is Recently, Cd-based materials (e.g., CdS, CdSe and metallic Cd) have been reported to convert CO2 to CO efficiently, due to the Cd sites can suppress the hydrogen evolution reaction (HER) and exhibit excellent CO anti-poisoning.[27,28,29] The previous works showed that tuning the coverage of surface hydroxyl groups and developing special morphology of catalysts can promote CO2 reduction and inhibit the HER.[30,31] As an important and conventional semiconductor, cadmium hydroxide (Cdhy) has been applied in a wide range of elds, including solar cells, sensors, and cathode electrode materials of batteries.[32,33] It offers an opportunity for developing novel Cdhy catalysts, which may be favorable for improving the selectivity and activity of CO from CO2RR. It provides low Cd–O coordination, and exposes high activity (002) facet, which requires lower energy for the formation of CO. The selectivity and activity of CO2RR have been signi cantly improved in the ow cell and membrane electrode assembly (MEA),[35,36] the CO2 availability is low, and the product separation is high energy consumption.

Results

Conclusion