College of Materials Science and Engineering, Hunan Province Key Laboratory for Advanced Carbon Materials and Applied Technology, Hunan University, Changsha, 410082, P. R. China.
Chemistry Department, Faculty of Science, Fayoum University, Fayoum, 63514, Egypt.
ChemSusChem. 2020 Sep 18;13(18):5088-5099. doi: 10.1002/cssc.202001444. Epub 2020 Aug 10.
The sluggish kinetics of the oxygen evolution reaction (OER) at the anode severely limit hydrogen production at the cathode in water splitting systems. Although electrocatalytic systems based on cheap and earth-abundant copper catalysts have shown promise for water oxidation under basic conditions, only very few examples with high overpotential can be operated under acidic or neutral conditions, even though hydrogen evolution in the latter case is much easier. This work presents an efficient and robust Cu-based molecular catalyst, which self-assembles as a periodic film from its precursors under aqueous conditions on the surface of a glassy carbon electrode. This film catalyzes the OER under neutral conditions with impressively low overpotential. In controlled potential electrolysis, a stable catalytic current of 1.0 mA cm can be achieved at only 2.0 V (vs. RHE) and no significant decrease in the catalytic current is observed even after prolonged bulk electrolysis. The catalyst displays first-order kinetics and a single site mechanism for water oxidation with a TOF (k ) of 0.6 s . DFT calculations on of the periodic Cu(TCA) (HTCA=1-mesityl-1H-1,2,3-triazole-4-carboxylic acid) film reveal that TCA defects within the film create Cu active sites that provide a low overpotential route for OER, which involves Cu , Cu -OH, Cu =O and Cu -OOH intermediates and is enabled at a potential of 1.54 V (vs. RHE), requiring an overpotential of 0.31 V. This corresponds well with an overpotential of approximately 0.29 V obtained experimentally for the grown catalytic film after 100 CV cycles at pH 6. However, to reach a higher current density of 1 mA cm , an overpotential of 0.72 V is required.
在水分解系统中，阳极析氧反应（OER）的缓慢动力学严重限制了阴极的氢气生成。虽然基于廉价且丰富的铜催化剂的电催化体系在碱性条件下显示出了水氧化的前景，但只有极少数具有高过电位的例子可以在酸性或中性条件下运行，尽管在后一种情况下析氢要容易得多。本工作提出了一种高效且稳定的基于铜的分子催化剂，它可以在玻璃碳电极表面的水溶液中自组装成周期性薄膜。该薄膜在中性条件下可催化 OER，过电位极低。在控制电位电解中，仅在 2.0 V（相对于 RHE）时即可实现稳定的催化电流为 1.0 mA cm ，并且即使在长时间的本体电解后，也观察到催化电流没有明显下降。该催化剂显示出一级动力学和单活性位机制的水氧化，TOF（k ）为 0.6 s 。周期性 Cu(TCA)（HTCA=1-均三甲苯基-1H-1,2,3-三唑-4-羧酸）薄膜的 DFT 计算表明，薄膜内的 TCA 缺陷会形成 Cu 活性位，为 OER 提供低过电位途径，涉及 Cu 、Cu-OH、Cu=O 和 Cu-OOH 中间体，在 1.54 V（相对于 RHE）的电位下即可发生，过电位为 0.31 V。这与在 pH 6 下经过 100 次 CV 循环后生长的催化薄膜的实验过电位约为 0.29 V 非常吻合。然而，要达到更高的电流密度 1 mA cm ，则需要 0.72 V 的过电位。
