Achieving Excellent H₂ Evolution Activity of Silver Nanocatalyst by a Simple Electrochemical Treatment Process

Silver nanoparticles (AgNPs) were synthesized in an aqueous solution via the reduction of AgNO₃ employing citrate reducing agent. The resultant AgNPs were first assayed for the catalytic H₂ evolution in an acidic electrolyte, namely pH 0.3 H₂SO₄ solution, showing negligible activity. The AgNPs were then conditioned in the same electrolyte solution while repeating the cyclic potential polarization between -0.25 V and 0.95 V (or 1.8 V) versus RHE. Effects of the electrochemical treatment to the morphology, crystalline, surface chemistry and H₂ evolution catalytic activity of AgNPs were examined. It was found that the electrochemical treatment remarkably boosted the H₂ evolution catalytic activity of AgNPs. The electrochemically activated AgNPs represents an attractive Pt-free catalyst for the H₂ evolution in acidic medium.