Grain-Boundary-Enriched Copper Electrocatalysts for Efficient Carbon Dioxide Reduction to Multi-Carbon Products

BinPeng, Xin-YuanChen, Ya-XinXie, RuiShu, Li-JuanShi, Hui-JuanGuo*, Fan-PengCheng, QunYi*

10.1021/acs.iecr.5c00765

Abstract:

 The electrocatalytic carbon dioxide reduction reaction (CO2RR) provides a promising strategy for converting CO² into valuable chemicals, with multicarbon (C²⁺) products being particularly attractive due to their diverse industrial applications. Grain boundaries in Cu-based electrocatalysts have been demonstrated to improve the selectivity of the CO₂RR toward C₂₊ products. However, methods for creating grain boundaries in Cu remain limited. Herein, a grain-boundary-enriched Cu electrocatalyst (GB-Cu) was successfully synthesized via in situ electrodeposition, in which sodium pyridine-2-carboxylate is introduced as an additive to control the deposition kinetics and generate new active species through the presence of GB. In situ attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy reveals that the abundance of grain boundaries enhances CO adsorption during C-C coupling. This leads to a significantly higher Faradaic efficiency (FE) of 57.7% for C₂₊ products, with a notable 43% for C₂H₄, in the H-cell. Furthermore, GB-Cu demonstrated high C²⁺ selectivity over a wide range of current densities (100-250 mA cm^-2) in a flow cell, achieving the highest C²⁺ FE of 50.03% at 100 mA cm^-2.

电催化二氧化碳还原反应（CO2RR）为将二氧化碳转化为高附加值化学品提供了一种有前景的策略，其中多碳（C2+）产物因其广泛的工业应用而备受关注。研究表明，铜基电催化剂中的晶界能够提升CO2RR生成C2+产物的选择性。然而，目前在铜中引入晶界的方法仍然有限。本研究中，通过原位电沉积方法成功合成了一种富含晶界的铜电催化剂（GB-Cu），在电沉积过程中引入吡啶-2-羧酸钠作为添加剂，用于调控沉积动力学行为，并通过晶界的存在生成新的活性物种。原位衰减全反射傅里叶变换红外光谱（ATR-FTIR）表明，晶界的丰富增强了C–C耦合过程中对CO的吸附能力。这使得在H型电解池中，C2+产物的法拉第效率（FE）达到57.7%，其中乙烯（C2H4）的效率显著高达43%。此外，在流动电解池中，GB-Cu在较宽的电流密度范围（100–250 mA cm⁻²）内均表现出优异的C2+选择性，在100 mA cm⁻²下实现了最高达50.03%的C2+法拉第效率。