<i>In Situ</i> Reconstruction of Scalable Amorphous Indium-Based Metal–Organic Framework for CO<sub>2</sub> Electroreduction to Formate over an Ultrawide Potential Window
Ziyun Liu, Xinxin Han, Junhui Liu, Shixia Chen, Shuguang Deng, Jun Wang
Abstract
Amorphous metal–organic frameworks (aMOFs) are highly attractive for electrocatalytic applications due to their exceptional conductivity and abundant defect sites, but harsh preparation conditions of “top-down” strategy have hindered their widespread use. Herein, the scalable production of aMIL-68(In)-NH 2 was successfully achieved through a facile “bottom-up” strategy involving ligand competition with 2-methylimidazole. Multiple in situ and ex situ characterizations reveal that aMIL-68(In)-NH 2 evolutes into In/In 2 O 3– x as the genuine active sites during the CO 2 electrocatalytic reduction (CO 2 RR) process. Moreover, the retained amino groups could enhance the CO 2 adsorption. As expected, the reconstructed catalyst demonstrates high formate Faradaic efficiency values (>90%) over a wide potential range of 800 mV in a flow cell, surpassing most top-ranking electrocatalysts. Density functional theory calculations reveal that the abundant oxygen vacancies in aMIL-68(In)-NH 2 induce more local charges around electroactive sites, thereby promoting the formation of HCOO* intermediates. Furthermore, 16 g of samples can be readily prepared in one batch and exhibit almost identical CO 2 RR performances. This work offers a feasible batch-scale strategy to design amorphous MOFs for the highly efficient electrolytic CO 2 RR.