Superior Performance of Ag over Pt for Hydrogen Evolution Reaction in Water Electrolysis under High Overpotentials

Abstract

There has been a substantial research effort worldwide to develop non-noble metal catalysts in electrolyzers for H2 production from renewable energy sources. Pt catalysts are found to display the highest hydrogen evolution reaction (HER) activity under typical experimental conditions with relatively low acidity and overpotentials. However, it is noted that catalytic activity is highly dependent on acidity and applied potential used. In real practice of a high workload electrolyzer, high acidity and large negative potentials are required to optimize the HER activity. We hereby report that inexpensive silver catalysts, particularly the cubic form of silver nanoparticles, can clearly exhibit superior HER activity over Pt with a different rate-determining step in an electrolyzer when such conditions are reached. This is attributed to the weaker Ag–H bond at the surface than Pt–H which is more favorable for H recombination to form H2. It is thus believed that this study provides new insights into designing economical and highly efficient catalysts that can replace the expensive noble metal analogues in a working electrolyzer.