Scalable Silver Oxo-Sulfide Catalyst for Electrochemical Water Splitting

Abstract

One of the bottlenecks toward the successful implementation of alternative energies is the lack of methods for sustainable generation of hydrogen fuel as an energy carrier. Given that water will be at the very least an important component of the hydrogen production feedstock, sustainable catalysts are needed for the electrochemical generation of hydrogen from water. Herein, we report on the electrochemical activation of a silver-based catalyst for the efficient hydrogen evolution reaction (HER) in acidic conditions at high current densities. After activation, the catalyst is chemically and electrochemically stable over days. The starting material, silver sulfide, is synthesized by a simple and scalable chemical vapor deposition process. Upon electrochemical activation, the pristine material is converted to mesoporous silver coated with a silver oxo-sulfide layer which is highly active toward HER. Detailed microscopy and spectroscopy demonstrate the formation of both hydroxyl and sulfoxide groups on the surface of the catalyst. Interestingly, the density functional theory calculations suggest that only in the presence of these hydroxyl groups will sulfur atoms exhibit high catalytic activity with a hydrogen binding energy of −0.35 eV.

Scalable Synthesis of Few-Layered 2D Tungsten Diselenide (2H-WSe2) Nanosheets Directly Grown on Tungsten (W) Foil Using Ambient-Pressure Chemical Vapor Deposition for Reversible Li-Ion Storage

“…Note that we used the “fast heat technique” according to the thermal annealing reported in our previous papers, but performed a slow cooling of our sample to room temperature while it was still inside the furnace. We also synthesized our material in a two-furnace system rather than a three-zone furnace, which we described during our earlier reports . When we took out the final product from the furnace, we observed a dull gray coating covering the upper exposed surface of the W foil.…”

“…We also synthesized our material in a two-furnace system rather than a three-zone furnace, which we described during our earlier reports. 65 When we took out the final product from the furnace, we observed a dull gray coating covering the upper exposed surface of the W foil. We refined the process parameters further by varying the growth times of tungsten diselenide (WSe 2 ) at 1 min, 5 min, 15 min, 30 min, 45 min, 1 h, 1.5 h, and 2 h. We also tested lower growth temperatures of 600, 650, 700, 750, 800, and 850 °C, but none of them showed any observable growth on the surface of the tungsten (W) foil (the details being explained further in the Results and Discussion section).…”

Higher Ultrasonic Frequency Liquid Phase Exfoliation Leads to Larger and Monolayer to Few-Layer Flakes of 2D Layered Materials

“…Natural graphite flakes (99.9%, mesh 10, Alfa Aesar), copper sulfide (Cu 9 S 5 ), and silver sulfide (Ag 2 S), synthesized according to a procedure reported in our previous papers, , were used as starting materials for our exfoliation experiments. Graphite was used as purchased without any additional treatments.…”