Gradient Doping of Tandem Catalysts to Boost Ethanol Production at Low Potential during CO<sub>2</sub> Electroreduction
Lidan Sun, Zhongxin Song, Mianrui Lin, JianZhao Peng, Yuanrui Li, Ruoyu Wei, Qingfeng Zhang, Jun Yu, Lei Zhang
Abstract
The electrochemical reduction of carbon dioxide (CO 2 ER) to valuable C 2+ chemicals has been demonstrated to be an effective and sustainable method using Cu-based catalysts. However, Cu catalysts still suffer from certain limitations, including high overpotential, low selectivity, and competitive hydrogen evolution. To achieve the valuable ethanol (C 2 H 5 OH) product from the CO 2 ER, a novel tandem catalyst featuring gradient doping of Cu in concave Pd nanoparticles (GD-PdCu 1.8 NPs) was designed in this study. Electrochemical tests conducted on the GD-PdCu 1.8 electrode reveal a nearly 100% faradaic efficiency (FE) for liquid products and a high FE of 40.0% for C 2 H 5 OH at the extremely low potential of −0.2 V versus the reversible hydrogen electrode (vs RHE). Furthermore, in-situ attenuated total reflection surface-enhanced infrared absorption spectroscopy (ATR-SEIRAS) and density functional theory (DFT) calculations provide insights into the underlying mechanism, indicating that gradient Cu doping in Pd can effectively facilitate the abundant formation of *CO, which then promotes the C–C asymmetric coupling step and ultimately leads to the production of C 2 H 5 OH with high selectivity. This study unveils the novel gradient doping of the tandem catalyst strategy to enhance multicarbon product selectivity at a relatively low overpotential for CO 2 ER, which can inform the rational catalyst design in the sustainable carbon cycle with high energy efficiency.