Boosting Formate Production in Electrocatalytic CO2 Reduction over Wide Potential Window on Pd Surfaces
Boosting Formate Production in Electrocatalytic CO2 Reduction over Wide Potential Window on Pd Surfaces
复制标题
在 Pd 表面的宽电位窗口内提高电催化 CO2 还原中的甲酸盐产量
DOI：
10.1021/jacs.7b12506
复制
发表时间：
2018-02-28
影响因子：
15
通讯作者：
Cai, Wen-Bin
中科院分区：
文献类型：
--
作者：
Jiang, Bei;Zhang, Xia-Guang;Cai, Wen-Bin
二氧化碳与甲酸盐/甲酸(FA)之间的快速相互转化在能量储存和转化以及中性碳排放方面具有广泛的应用价值。过去，二氧化碳在Pd表面还原甲酸盐的电化学反应被限制在-0.25V(Vs RHE)的窄电位范围内。本文以Pd/C为参照物，初步探索了一种能在-0.2~-1.0 V(Vs RHE)电位范围内电化学还原CO2的掺硼Pd催化剂(Pd-B/C)，该催化剂具有较高的CO耐受性，在-0.5 V(Vs RHE)下，0.1M KHCO3溶液中电解2 h，甲酸盐的法拉第效率(ETA(-)(HCOO))可达70%左右。这是国产或商用Pd/C催化剂的约12倍，在没有优化催化剂层和电解液的情况下，甲酸盐浓度约为234 mm mg(-1)Pd，约为Pd/C的18倍。此外，Pd-B/C上的竞争选择性ETA(-)(HCOO)/ETA(CO)始终显著高于Pd/C，尽管在-0.5V时ETA(-)(HCOO)降低，CO法拉第效率(ETA(CO))增加。对模拟的Pd(111)表面上有和没有H-吸附的CO2还原反应的能量进行密度泛函理论(DFT)计算表明，B掺杂在Pd亚表面更有利于吸附的HCOO*的形成，HCOO*是FA途径的中间产物，一氧化碳途径的中间体。本研究为Pd-B/C提供了一种独特的双功能催化剂，用于HCOOH-CO2的相互转化。
Facile interconversion between CO2 and formate/formic acid (FA) is of broad interest in energy storage and conversion and neutral carbon emission. Historically, electrochemical CO2 reduction reaction to formate on Pd surfaces was limited to a narrow potential range positive of -0.25 V (vs RHE). Herein, a boron-doped Pd catalyst (Pd-B/C), with a high CO tolerance to facilitate dehydrogenation of FA/formate to CO2 is initially explored for electrochemical CO2 reduction over the potential range of -0.2 V to -1.0 V (vs RHE), with reference to Pd/C. The experimental results demonstrate that the faradaic efficiency for formate (eta(-)(HCOO)) reaches ca. 70% over 2 h of electrolysis in CO2-saturated 0.1 M KHCO3 at -0.5 V (vs RHE) on Pd-B/C, that is ca. 12 times as high as that on homemade or commercial Pd/C, leading to a formate concentration of ca. 234 mM mg(-1) Pd, or ca. 18 times as high as that on Pd/C, without optimization of the catalyst layer and the electrolyte. Furthermore, the competitive selectivity eta(-)(HCOO)/eta(CO) on Pd-B/C is always significantly higher than that on Pd/C despite a decreases of eta(-)(HCOO) and an increases of the CO faradaic efficiency (eta(CO)) at potentials negative of -0.5 V. The density functional theory (DFT) calculations on energetic aspects of CO2 reduction reaction on modeled Pd(111) surfaces with and without H-adsorbate reveal that the B-doping in the Pd subsurface favors the formation of the adsorbed HCOO*, an intermediate for the FA pathway, more than that of *COOH, an intermediate for the CO pathway. The present study confers Pd-B/C a unique dual functional catalyst for the HCOOH CO2 interconversion.