Nitrogen-free charge-asymmetric indium cluster catalyst for efficient CO ₂ electroreduction to formate

Electrochemical CO₂ reduction reaction (CO₂RR) into high-value chemicals and fuels is recognized as a promising strategy for mitigating energy and environmental challenges. However, this process frequently faces limitations due to inadequate selectivity towards specific products and insufficient electrochemical stability. Main group indium (In) catalysts have emerged as promising materials for CO₂RR to highly valued formate. In this study, we constructed an indium cluster material with charge-asymmetric atomic structure anchored on nitrogen-free carbon nanoframeworks (designated as In Clu/C), which exhibits exceptional efficiency as a CO₂RR catalyst for formate production. Notably, the In Clu/C achieves a remarkable formate Faradaic efficiency of 98.7% at −0.70 V. Furthermore, <i>in-situ</i> X-ray absorption spectroscopy (XAS) measurements reveal that the superior catalytic performance can be attributed to partially positively charged In<i>^δ</i>⁺ (0 &lt; <i>δ</i> &lt; 3) active sites. This discovery may provide new insights into the precise synthesis of metal cluster catalysts for environmental and energy applications.