In<sup>3+</sup>-Induced In–O–Sn Superexchange and Oxygen Vacancies Synergistically Boosting Acidic CO<sub>2</sub>-to-HCOOH Electrolysis at Ampere-Current Levels over Sn-Based Perovskite Oxides
Junjie Zhu, Junjie Zhu, Hongyan Zhao, Qi Wang, Haijiao Kong, Xiaoyue Tu, Yu Zhang, Zhihui Lv, Zhenbao Zhang, Xiangjian Liu, Zhen Xue, Lei Shi, Xin‐Ming Hu, Jiawei Zhu, Jiawei Zhu, Heqing Jiang, Yongfa Zhu
Abstract
Sn-based catalysts feature significant potential for acidic CO 2 electroreduction (CO 2 RR) to HCOOH, but encounter unsatisfactory selectivity and poor stability, especially at high current densities. Here, we report In 3+ -induced In–O–Sn superexchange and oxygen vacancies synergistically enabling ampere-level, selective, and stable CO 2 -to-HCOOH electroreduction over Sn-based perovskite oxides in a strong acid. For the proof-of-concept catalysts of SrSn 1– x In x O 3−δ ( x = 0.05, 0.1, and 0.2), In 3+ introduction not only generates additional oxygen vacancies but also engenders marked In–O–Sn superexchange. This superexchange modulates electronic structures, including the upward-shifted band center ( e.g., Sn 5p) and the strengthened Sn–O bond covalency. In HCOOH production, relative to the parent SrSnO 3, the SrSn 1– x In x O 3−δ series demonstrate enhancements in activity and selectivity (more pronounced with In 3+ content) while also featuring significantly boosted stability. In strong acid (pH = 1), SrSn 0.8 In 0.2 O 3−δ achieves high HCOOH selectivity of 91.2% at 1 A cm –2 and a single-pass carbon efficiency of up to 81.0%, together with a steady operation over 80 h, outperforming previously reported Sn-based catalysts. Our experiments and theoretical calculations attribute these performance improvements to the following factors: the superexchange-shifted band centers and the additional oxygen vacancies synergistically facilitating *CO 2 protonation to *OCHO; the superexchange-strengthened Sn–O bond covalency stabilizing the Sn–O lattice.