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Researchers synthesize silver sulfide/reduced graphene oxide composite catalysts

(Nanowerk News) The development of efficient electrocatalyst to produce molecular hydrogen from water is receiving considerable attention, in an effort to decrease our reliance on fossil fuels. Silver sulfide (Ag2S) nanocrystals have attracted enormous interests due to its excellent properties.
At present, the performance of hydrogen generation reaction (HER) catalysts based on Ag2S nanocrystals are still at a certain distance from expectations. One of the main reasons is that the impeded charge transfer and decreased active sites caused by aggregation of Ag2S nanocrystals.
To solve this problem, a research team led by Prof. YU Weili from the Changchun Institute of Optics, Fine Mechanics, and Physics (CIOMP) of the Chinese Academy of Sciences and Prof. Hicham Idriss of King Abdullah University of Science and Technology (KAUST) synthesized Ag2S/rGO composite catalysts with smaller crystal size and better charge transfer properties by the solution fabrication strategy.
The study was published in Catalysts ("Effect of Ag2S Nanocrystals/Reduced Graphene Oxide Interface on Hydrogen Evolution Reaction").
Schematic of the HER reaction catalyzed by Ag2S/rGO
Schematic of the HER reaction catalyzed by Ag2S/rGO (Image: CIOMP)
The researchers combined the high quality Ag2S nanocrystals with reduced graphene oxide with high carrier mobility, and prepared efficient HER catalysts.
Compared to catalyst based on pure Ag2S nanocrystals, the Ag2S/rGO composites catalyst showed a significant decrease of overpotential, Tafel slope and electrochemical resistance. Transmission electron microscope (TEM) images showed that the induced rGO provided abundant nucleation sites, thus preventing the aggregation of Ag2S nanocrystals.
The average size of Ag2S nanocrystals grown on rGO was calculated to be about 7 nm.
Time-resolved photoluminescence (TRPL) studies showed that the improvement of the catalystic performance was mainly attributed to the efficient charge transfer of the Ag2S/rGO composites.
In this study, Ag2S nanocrystals and two-dimensional material rGO are effectively combined to improve the catalytic performance through the synergistic advantages of the two materials in carrier transfer and aggregation inhibition.
The study provides a new way for the preparation of high performance composite HER catalysts.
Source: Chinese Academy of Sciences
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