Noble metal aerogels rapidly synthesized by ultrasound for electrocatalytic reaction

Abstract

Noble metal aerogels (NMAs), belonging to the porous material, have exhibited excellent catalytic performance. Although the synthesis method continues to improve, it still exists some problems which hindered the experimental process, such as high concentration of noble metal precursors, long synthesis cycle, expensive production cost, and uncontrollable ligament length. In this work, ultrasonic wave and reducing agent NaBH4 were simultaneously applied to gelation process. With the cavitation of ultrasound, it can generate huge energy with heating and stirring, thus gelation reaction proceeded quickly, and even completed the process in only a few seconds, that is much faster than the recorded. A wide concentration range was successfully expanded from 0.02 mmol/L to 62.5 mmol/L. Further, we extended this method to a variety of noble metal elements (Au, Ru, Rh, Ag, Pt, Pd), and this method is adaptive for the synthesis of single metal aerogels (Au, Ag, Ru, Rh, Pd), bimetal and trimetal aerogels (Au-Ag, Au-Rh, Au-Ru, Au-Pt, Au-Pd, Au-Pt-Pd). In addition, the ligament size of alloy aerogels are 10 nm or less. Moreover, their brilliant properties were demonstrated in hydrogen evolution reaction (HER) and ethanol oxidation reaction (EOR).