Electrochemical reduction of carbon dioxide (CO 2 ) to high-value liquid fuel with high selectivity is appealing for energy conversion and storage. Here we report a bismuth phosphate (BiPO 4 ) derived 2D nanosheet-like electrocatalyst for efficiently converting CO 2 into liquid-phase formate. The catalyst presents a formate Faradaic efficiency over 90% and a cathodic energy efficiency of 73% at an industrially relevant current density of 200 mA cm -2 in flow cell. The in-situ generation of the Bi-O active species on the catalyst surface is determined via operando Raman measurement. Morphological and X-ray photoelectron spectroscopy analyses reveal the origin of the high activity for formate electrosynthesis from CO 2 and water: the 2D structure together with the rich oxygen atoms insertion in the surface of the BiPO 4 derived nanosheets.