Abstract
Aiming to achieve enhanced photocatalytic activity and stability toward the generation of H2 from water, we have synthesized noble metal-free core-shell nanoparticles of graphene (G)-wrapped CdS and TiO2 (CdS@G@TiO2) by a facile hydrothermal method. The interlayer thickness of G between the CdS core and TiO2 shell is optimized by varying the amount of graphene quantum dots (GQD) during the synthesis procedure. The most optimized sample, i.e., CdS@50G@TiO2 generated 1510 µmole g−1 h−1 of H2 (apparent quantum efficiency (AQE) = 5.78%) from water under simulated solar light with air mass 1.5 global (AM 1.5G) condition which is ~2.7 times and ~2.2 time superior to pure TiO2 and pure CdS respectively, along with a stable generation of H2 during 40 h of continuous operation. The increased photocatalytic activity and stability of the CdS@50G@TiO2 sample are attributed to the enhanced visible light absorption and efficient charge separation and transfer between the CdS and TiO2 due to incorporation of graphene between the CdS core and TiO2 shell, which was also confirmed by UV-vis, photoelectrochemical and valence band XPS measurements.
Highlights
The burning of fossil fuels to meet the energy demands of modern society is increasing global warming exponentially and leading to the depletion of conventional energy sources which may soon result in a severe energy crisis [1]
We have demonstrated enhanced photocatalytic activity for H2 generation along with promising catalyst stability by synthesizing the core-shell nanoparticles of cadmium sulfide (CdS) and TiO2 [16]
Motivated to avail the benefits of placing the conductor layer in the heterojunction of two semiconductors and to further enhance the photocatalytic activity of our previously developed core-shell nanoparticles of CdS and TiO2 [16], we have introduced a conductive layer of graphene (G) between the CdS core and TiO2 shell (CdS@G@TiO2 )
Summary
The burning of fossil fuels to meet the energy demands of modern society is increasing global warming exponentially and leading to the depletion of conventional energy sources which may soon result in a severe energy crisis [1]. To mitigate these serious issues, a renewable and environmentally friendly alternative energy transformation carrier is urgently needed. In the past few years, extensive efforts have been devoted to explore and investigate new approaches for the development of highly efficient and stable photocatalyst for H2 generation from water.
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