Laboratory of Nanochemistry for Energy Research, Institute of Chemical Sciences and Engineering, Ecole Politechnique Fédérale de Lausanne, Sion CH-1950, Switzerland.
Swiss-Norwegian Beamlines, European Synchrotron Radiation Facility, 38000 Grenoble, France.
J Am Chem Soc. 2023 Mar 8;145(9):5370-5383. doi: 10.1021/jacs.2c13437. Epub 2023 Feb 27.
Copper nanocatalysts are among the most promising candidates to drive the electrochemical CO reduction reaction (CORR). However, the stability of such catalysts during operation is sub-optimal, and improving this aspect of catalyst behavior remains a challenge. Here, we synthesize well-defined and tunable CuGa nanoparticles (NPs) and demonstrate that alloying Cu with Ga considerably improves the stability of the nanocatalysts. In particular, we discover that CuGa NPs containing 17 at. % Ga preserve most of their CORR activity for at least 20 h while Cu NPs of the same size reconstruct and lose their CORR activity within 2 h. Various characterization techniques, including X-ray photoelectron spectroscopy and operando X-ray absorption spectroscopy, suggest that the addition of Ga suppresses Cu oxidation at open-circuit potential (ocp) and induces significant electronic interactions between Ga and Cu. Thus, we explain the observed stabilization of the Cu by Ga as a result of the higher oxophilicity and lower electronegativity of Ga, which reduce the propensity of Cu to oxidize at ocp and enhance the bond strength in the alloyed nanocatalysts. In addition to addressing one of the major challenges in CORR, this study proposes a strategy to generate NPs that are stable under a reducing reaction environment.
铜纳米催化剂是推动电化学 CO 还原反应（CORR）最有前途的候选者之一。然而，此类催化剂在运行过程中的稳定性并不理想，提高催化剂行为的稳定性仍然是一个挑战。在这里，我们合成了具有明确结构和可调谐性的 CuGa 纳米颗粒（NPs），并证明了 Ga 与 Cu 的合金化可显著提高纳米催化剂的稳定性。具体来说，我们发现，含有 17 原子% Ga 的 CuGa NPs 在至少 20 小时内保留了大部分 CORR 活性，而相同尺寸的 Cu NPs 在 2 小时内重构并失去了 CORR 活性。包括 X 射线光电子能谱和原位 X 射线吸收光谱在内的各种表征技术表明，Ga 的添加抑制了开路电位（ocp）下的 Cu 氧化，并在 Ga 和 Cu 之间诱导了显著的电子相互作用。因此，我们将 Ga 对 Cu 的稳定作用解释为 Ga 的更高氧化亲合性和更低电负性的结果，这降低了 Cu 在 ocp 下氧化的趋势，并增强了合金纳米催化剂中的键强度。除了解决 CORR 中的主要挑战之一外，本研究还提出了一种策略，用于生成在还原反应环境下稳定的 NPs。
