Au aerogel for selective COelectroreduction to CO: ultrafast preparation with high performance.

Noble metal aerogels (NMAs) have been used in a variety of (photo-)electrocatalytic reactions, but pure Au aerogel (AG) has not been used in COelectroreduction to date. To explore the potential application in this direction, AG was prepared to be used as the cathode in COelectroreduction to CO. However, the gelation time of NMAs is usually very long, up to several weeks. Here, an excess NaBHand turbulence mixing-promoted gelation approach was developed by introducing magnetic stirring as an external force field, which therefore greatly shortened the formation time of Au gels to several seconds. The AG-3 (AG with Au loading of 0.003 g) exhibited a high CO Faradaic efficiency (FE) of 95.6% at an extremely low overpotential of 0.39 V, and over 91% of CO FE was reached in a wide window of -0.4 to -0.7 V versus the reversible hydrogen electrode (RHE). Partial current density in CO was measured to be -19.35 mA cmat -0.8 V versus RHE under 1 atm of CO. The excellent performance should be ascribed to its porous structure, abundant active sites, and large electrochemical active surface area. It provides a new method for preparation of AG with ultrafast gelation time and large production at room temperature, and the resulting pure AG was for the first time used in the field of COelectroreduction.