通过使用局部静电相互作用控制不对称的甲的氧降低选择性
1Simon Fraser University, Department of Chemistry, 8888 University Drive, Burnaby BC V5A 1S6 Canada.
Journal of the American Chemical Society
|July 25, 2020
概括
开发新的氧降解反应 (ORR) 电催化剂至关重要. 这项研究使用阴离子辅助组增强了甲ORR催化剂,在广泛的pH范围内实现了高选择性.
科学领域:
- 电化学
- 材料科学
- 催化剂
背景情况:
- 氧降解反应 (ORR) 的电催化剂对于能量转化技术至关重要.
- 提高ORR的选择性和动力学,特别是将O2降低到H2的4H+/4e,仍然是一个重大挑战.
- 靠近活性部位的辅助组可以增强催化剂的性能,但色素的策略与铁色素的策略不同.
研究的目的:
- 为铁甲ORR催化剂开发的辅助组调整策略,以改进甲催化剂.
- 合成和研究一系列具有不同辅助组的改性甲电催化剂.
- 为了确定这些修改对ORR选择性和动力学在pH值范围的影响.
主要方法:
- 与 -NH2, -N(CH3) 2,和 -N(CH3) 3辅助组的 Co5,10,15,20-tetraphenylporphyrin) 衍生物的合成
- 使用循环电量测量和水力动力学电化学的电化学研究.
- 量子化学计算以阐明反应机制.
主要成果:
- 一个阴离子辅助组 (-N(CH3) 3+) 导致O2转化为H2O在广泛的pH范围 (0-7).
- 其他催化剂在更高的pH值下产生H2O2,而不是阴离子变体.
- -N(CH3) 3改性催化剂表现出稳定的ORR率为~106 M-1 s-1,选择性从pH0到7.
结论:
- 阴离子辅助组在增强甲电催化剂的选择性方面非常有效,使O2完全减少到H2O.
- 甲的机制可能涉及离子,过氧化物结合的中间体,这表明静电稳定是关键.
- 对于甲ORR催化剂而言,O2结合的中间体的静电稳定比铁甲中使用的辅助组更为关键.
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