Two-Dimensional BiPS ₄ -Derived Catalyst for the Selective Electroreduction of CO ₂ : The Synergistic Effect of Phosphorus and Sulfur along with Bismuth

Electrochemical CO2 reduction is a promising route to produce value-added fuels and chemicals, though it is an energy-intensive technique. However, achieving high faradaic efficiency and excellent activity in a broad potential range is crucial for further use in applications such as storage batteries. In this direction, electrochemical reduction of carbon dioxide (ECO2RR) to formic acid with high selectivity is considered one of the promising strategies. Bismuth-based catalysts possess chances of success, with room for improvement. The present study describes the use of a two-dimensional phosphochalcogenide to construct an active catalyst for CO2 reduction. Bismuth reconstructed from exfoliated 2D BiPS4 nanosheets is reported for the selective reduction of CO2 to formate. Various techniques like XPS, XRD, and in situ Raman spectroscopy reveal the transformation of the catalyst, identifying the formation of the sulfur-guided (012) facets preferentially as active sites for CO2 reduction. A high faradaic efficiency of 92% of HCOOH is obtained at a potential of −1.2 V vs RHE in an H-type cell with high stability. Scanning electrochemical microscopy (SECM) further confirms selective formate production during the electrolysis. In situ ATR-IR measurements reveal that the *OCHO intermediate is formed during the conversion of CO2 to formate. Due to its high efficiency and selectivity, the catalyst is further utilized as a cathode for the Zn–CO2 battery system, and the performance and cyclability are found to be good at various current densities. These findings highlight the probability of developing bismuth-based catalysts containing sulfur and phosphorus to improve the performance of ECO2RR and thus mark a viable path toward good electrocatalysts.