Activating inert non-defect sites in Bi catalysts using tensile strain engineering for highly active CO2 electroreduction
Xingbao Chen, Ruihu Lu, Chengbo Li, Wen Luo, Ruohan Yu, Jiexin Zhu, Lei Lv, Yuhang Dai, Shanhe Gong, Yazhou Zhou, Weiwei Xiong, Jiahao Wu, Hongwei Cai, Xinfei Wu, Zhaohui Deng, Boyu Xing, Lin Su, Fei Wang, Feiyang Chao, Wei Chen, Chuan Xia, Ziyun Wang, Liqiang Mai
Abstract
Bi-defect sites are highly effective for CO2 reduction (CO2RR) to formic acid, yet most catalytic surfaces predominantly feature inert, non-defective Bi sites. To overcome this limitation, herein, tensile strain is introduced on wholescale non-defective Bi sites. Under rapid thermal shock, the Bi-based metal-organic framework (Bi-MOF-TS) shows weakened Bi–O bonds and produced tiny Bi clusters. During electrochemical reduction, these clusters create numerous continuous vacancies, inducing weak tensile strain over a large range of surrounding non-defective Bi sites. This strain enhances *OHCO intermediates adsorption and substantially lowers the reaction barrier. As a result, Bi-MOF-TS achieves a faradaic efficiency above 90% across 800 mV potential range, with an impressive formate partial current density of −995 ± 93 mA cm−2. Notably, Bi-MOF-TS exhibits a high HCOOH faradaic efficiency of 96 ± 0.64% at 400 mA cm−2 in acidic electrolyte and a high single-pass carbon conversion efficiency (SPCE) of 62.0%. Additionally, a Zn-CO2 battery with Bi-MOF-TS as the cathode demonstrates a peak power density of 21.4 mW cm−2 and maintains stability over 300 cycles. A large range of inert and non-defective sites in catalysts is a primary factor impeding catalyst activity in acidic CO2 electroreduction. Here, the authors achieve high HCOOH selectivity and activity in acidic electrolyte by introducing tensile strain to activate inert sites.