Heterojunction of the CoMn Metal–Organic Framework with Lanthanum for Enhanced Oxygen Evolution Reaction
Yi Wang, Yi Wang, Bin Wang, Xiangyang Liu, Yajie Wang, Yajie Wang, Yichao Wang, Yichao Wang, Zhongqing Liu
Abstract
Surface and interfacial electron transfer tends to be the rate-limiting step in multiple electron electrocatalytic reactions such as oxygen evolution reaction (OER). Constructing a heterojunction structure is an effective approach to strengthen the processes. Here, CoMnLax-MOF/CF has been synthesized via a one-pot solvothermal pathway to integrate the charge transport advantage of the heterojunction and the mass-transfer superiority of high porosity of the metal–organic framework (MOF), wherein the heterojunction is formed by introducing La in preparing the CoMn-MOF process. The results demonstrate that the as-prepared CoMnLax-MOF/CF possesses flower-like/flower-bud microstructures with a CoMn-MOF/La-MOF heterojunction topology, resulting in superior OER performance. The enhanced OER property originates from reduced charge-transfer resistance and an enlarged activated surface area. At a molar ratio of nLa:nCo:nMn = 0.2:1:1, the CoMnLa0.2-MOF/CF presents optimal performance. In 1 M KOH, the overpotential is only 201 mV to reach 10 mA cm–2 current density. There appears no significant current density degeneration in the 25 h stability test. This work demonstrates one facile pathway for directly building the heterojunction in CoMn-MOF to achieve superb OER activity.