Abstract：
Due to their abundant active sites and porous structures, metal-organic frameworks (MOFs) have garnered significant interest as oxygen evolution reaction (OER) electrocatalysts. Nevertheless, the development of MOF-based electrocatalysts with efficient OER activity and excellent stability simultaneously still faces challenges. Herein, a cathodic activation strategy was used to enhance the OER electrocatalytic performance of M-HHTP for the first time, where M refers to Ni, Cu, Co, Fe, while HHTP denotes 2, 3, 6, 7, 10, 11-hexahydroxytriphenylene. As a prototype, the activated Ni-HHTP (HA-Ni-HHTP) demonstrates outstanding OER performance, with an overpotential as low as 140 mV at 20 mA cm-2 and a small Tafel slope of 78.7 mV-1, surpassing commercial RuO2 and rivaling state-of-the-art MOFs-based electrocatalysts. Characterizations and density functional theory calculations reveal that the superior performance of HA-Ni-HHTP is primarily ascribed to changes in semiconductor type, contact angle, and oxygen vacancy content induced by cathodic activation. Electrochemical impedance spectroscopy analysis using the transmission line model confirms that cathodic activation accelerates charge transport, enhancing the OER process. Furthermore, the cathodic activation strategy holds promise for improving the water oxidation performance of other MOFs such as Fe-HHTP, Co-HHTP, and Cu-HHTP.
摘要：
由于其丰富的活性位点和多孔结构，金属有机骨架(MOFs)作为析氧反应(OER)电催化剂已经引起了人们的极大兴趣。然而，同时具有高效OER活性和优异稳定性的MOF基电催化剂的开发仍然面临挑战。在这里，首次采用阴极活化策略提高了M-HHTP的OER电催化性能,其中M是指Ni，Cu,Co,Fe,而HHTP表示2,3,6,7,10,11-六羟基三亚苯基。作为原型,活化的Ni-HHTP（HA-Ni-HHTP）具有出色的OER性能，具有在20mAcm-2时低至140mV的超电势和78.7mV-1的小Tafel斜率，超过了商业RuO2，并与最先进的基于MOF的电催化剂相媲美。表征和密度泛函理论计算表明，HA-Ni-HHTP的优异性能主要归因于半导体类型的变化，接触角,和阴极活化引起的氧空位含量。使用传输线模型的电化学阻抗谱分析证实，阴极活化加速了电荷传输，加强OER过程。此外，阴极活化策略有望改善其他MOFs的水氧化性能，如Fe-HHTP，Co-HHTP,和Cu-HHTP。
