Department of Chemistry, University of California Berkeley , Berkeley, California 94720, United States.
The Molecular Foundry, Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States.
J Am Chem Soc. 2017 Mar 22;139(11):4052-4061. doi: 10.1021/jacs.6b12217. Epub 2017 Mar 7.
Regulating the complex environment accounting for the stability, selectivity, and activity of catalytic metal nanoparticle interfaces represents a challenge to heterogeneous catalyst design. Here we demonstrate the intrinsic performance enhancement of a composite material composed of gold nanoparticles (AuNPs) embedded in a bottom-up synthesized graphene nanoribbon (GNR) matrix for the electrocatalytic reduction of CO. Electrochemical studies reveal that the structural and electronic properties of the GNR composite matrix increase the AuNP electrochemically active surface area (ECSA), lower the requisite CO reduction overpotential by hundreds of millivolts (catalytic onset > -0.2 V versus reversible hydrogen electrode (RHE)), increase the Faraday efficiency (>90%), markedly improve stability (catalytic performance sustained over >24 h), and increase the total catalytic output (>100-fold improvement over traditional amorphous carbon AuNP supports). The inherent structural and electronic tunability of bottom-up synthesized GNR-AuNP composites affords an unrivaled degree of control over the catalytic environment, providing a means for such profound effects as shifting the rate-determining step in the electrocatalytic reduction of CO to CO, and thereby altering the electrocatalytic mechanism at the nanoparticle surface.
调控催化金属纳米粒子界面的稳定性、选择性和活性的复杂环境是对多相催化剂设计的一个挑战。在这里，我们展示了由金纳米粒子（AuNPs）嵌入自下而上合成的石墨烯纳米带（GNR）基质组成的复合材料在 CO 电化学还原中的固有性能增强。电化学研究表明，GNR 复合基质的结构和电子特性增加了 AuNP 的电化学活性表面积（ECSA），使 CO 还原的过电位降低了数百毫伏（催化起始>-0.2 伏相对于可逆氢电极（RHE）），增加了法拉第效率（>90%），显著提高了稳定性（超过 24 小时的催化性能持续），并提高了总催化输出（比传统非晶态碳 AuNP 载体提高了 100 多倍）。自下而上合成的 GNR-AuNP 复合材料的固有结构和电子可调性提供了对催化环境的无与伦比的控制程度，为改变纳米粒子表面的电催化机制提供了一种方法，例如将 CO 电化学还原的速率决定步骤转移到 CO。
