Electrochemical conversion of CO₂ into fuels is a promising means to solve greenhouse effect and recycle chemical energy. However, the CO₂ reduction reaction (CO₂RR) is limited by the high overpotential, slow kinetics and the accompanied side reaction of hydrogen evolution reaction. Au nanocatalysts exhibit high activity and selectivity toward the reduction of CO₂ into CO. Here, we explore the Faradaic efficiency (FE) of CO₂RR catalyzed by 50 nm gold colloid and trisoctahedron. It is found that the maximum FE for CO formation on Au trisoctahedron reaches 88.80% at −0.6 V, which is 1.5 times as high as that on Au colloids (59.04% at −0.7 V). The particle-size effect of Au trisoctahedron has also been investigated, showing that the FE for CO decreases almost linearly to 62.13% when the particle diameter increases to 100 nm. The X-ray diffraction characterizations together with the computational hydrogen electrode (CHE) analyses reveal that the (2 2 1) facets on Au trisoctahedron are more feasible than the (1 1 1) facets on Au colloids in stabilizing the critical intermediate COOH*, which are responsible for the higher FE and lower overpotential observed on Au trisoctahedron.

将CO ₂电化学转化为燃料是解决温室效应和循环利用化学能的有效途径。然而，CO ₂还原反应(CO ₂ RR)受限于过电位高、动力学缓慢以及析氢反应伴随的副反应。Au 纳米催化剂对将 CO ₂还原为 CO 表现出高活性和选择性。在这里，我们探讨了 CO _{2的法拉第效率 (FE)}RR 由 50 nm 金胶体和三八面体催化。发现在-0.6 V 时，Au 三八面体上 CO 形成的最大 FE 达到 88.80%，是 Au 胶体（-0.7 V 时为 59.04%）的 1.5 倍。还研究了 Au 三八面体的粒径效应，表明当粒径增加到 100 nm 时，CO 的 FE 几乎线性下降到 62.13%。X 射线衍射表征与计算氢电极 (CHE) 分析表明，在稳定关键的中间体 COOH* 方面，Au 三八面体上的 (2 2 1) 面比 Au 胶体上的 (1 1 1) 面更可行，这是导致在 Au 三八面体上观察到的较高 FE 和较低过电势的原因。