Rapid Fabrication of Defective CuInP2S6 Nanosheets for Efficient CO2-to-Formate Conversion over Wide Current Densities.

Electrochemical CO2 reduction reaction (CO2RR) to produce value-added chemicals offers a promising approach to mitigate global warming and address the energy crisis. However, the development of highly selective and durable catalysts that perform reliably across varying operational conditions remains challenging. In this work, we report the synthesis of lithium-intercalated CuInP2S6 (Li-CIPS) with a layered structure via a one-step chemical vapor transport method. Compared to pristine CuInP2S6, lithium intercalation in Li-CIPS facilitates the rapid production of ultrathin CuInP2S6 nanosheets through simple soaking in water. Experimental and theoretical investigations reveal that these ultrathin Li-CIPS nanosheets contain abundant sulfur vacancies (Vs), which can substantially enhance the CO2RR activity while suppressing the competing hydrogen evolution reaction. As a result, the Li-CIPS catalyst achieves over 90% Faradaic efficiency (FE) for formate production across wide current densities ranging from 100 to 800 mA cm-2, and it maintains stable operation over 100 h at 200 mA cm-2. This study highlights a promising and selective AMP2X6-based electrocatalyst for efficient CO2-to-formate conversion in practical applications.