Hunan Joint International Research Center for Carbon Dioxide Resource Utilization, State Key Laboratory of Powder Metallurgy, School of Physics and Electronics, Central South University, Changsha, 410083, P. R. China.
College of Materials Science and Engineering, Hunan University, Changsha, 410082, P. R. China.
Adv Mater. 2023 May;35(21):e2300695. doi: 10.1002/adma.202300695. Epub 2023 Apr 2.
Main group single atom catalysts (SACs) are promising for CO electroreduction to CO by virtue of their ability in preventing the hydrogen evolution reaction and CO poisoning. Unfortunately, their delocalized orbitals reduce the CO activation to *COOH. Herein, an O doping strategy to localize electrons on p-orbitals through asymmetric coordination of Ca SAC sites (Ca-N O) is developed, thus enhancing the CO activation. Theoretical calculations indicate that asymmetric coordination of Ca-N O improves electron-localization around Ca sites and thus promotes *COOH formation. X-ray absorption fine spectroscopy shows the obtained Ca-N O features: one O and three N coordinated atoms with one Ca as a reactive site. In situ attenuated total reflection infrared spectroscopy proves that Ca-N O promotes *COOH formation. As a result, the Ca-N O catalyst exhibits a state-of-the-art turnover frequency of ≈15 000 per hour in an H-cell and a large current density of -400 mA cm with a CO Faradaic efficiency (FE) ≥ 90% in a flow cell. Moreover, Ca-N O sites retain a FE above 90% even with a 30% diluted CO concentration.
主族单原子催化剂 (SACs) 具有防止析氢反应和 CO 中毒的能力，因此在 CO 电还原为 CO 方面具有广阔的应用前景。然而，其离域轨道降低了 CO 向 *COOH 的活化程度。在此，通过 Ca SAC 位点（Ca-N O）的不对称配位开发了一种 O 掺杂策略，以通过非对称配位将电子局域在 p 轨道上，从而增强 CO 的活化。理论计算表明，Ca-N O 的不对称配位改善了 Ca 位点周围的电子局域化程度，从而促进了 *COOH 的形成。X 射线吸收精细光谱显示了所获得的 Ca-N O 的特征：一个 O 和三个 N 配位原子与一个作为反应位点的 Ca。原位衰减全反射红外光谱证明了 Ca-N O 促进了 *COOH 的形成。结果表明，Ca-N O 催化剂在 H 电池中具有约 15000 每小时的出色周转频率和在流动电池中具有-400 mA cm 的大电流密度，且 CO 法拉第效率 (FE)≥90%。此外，即使在 CO 浓度稀释 30%的情况下，Ca-N O 位点仍保持超过 90%的 FE。
