Researchers at the University of Central Florida, with colleagues at Pacific Northwest National Laboratory (PNNL) and Tsinghua University, developed a new hybrid nanomaterial—a nonmetal plasmonic MoS2@TiO2 heterostructure—for highly efficient photocatalytic H2 generation from water.
As reported in an open access paper in the RSC journal Energy & Environmental Science, the new catalyst is not only able to harvest a much broader spectrum of light than other materials, but can also stand up to the harsh conditions found in seawater.
To create the hybrid material, the team, led by UCF researcher Yang Yang, chemically etched tiny nanocavities onto the surface of an ultrathin film of titanium dioxide, the most common photocatalyst. Those nanocavity indentations were coated with nanoflakes of molybdenum disulfide, a two-dimensional material with the thickness of a single atom.
Typical catalysts are able to convert only a limited bandwidth of light to energy. With its new material, Yang's team is able to significantly boost the bandwidth of light that can be harvested. By controlling the density of sulfur vacancy within the nanoflakes, they can produce energy from ultraviolet-visible to near-infrared light wavelengths, making it at least twice as efficient as current photocatalysts.
Broad spectral response ranging from ultraviolet-visible (UV-Vis) to near-infrared (NIR) wavelengths and finite element frequency-domain simulation suggest that this MoS2@TiO2 heterostructured photocatalyst enhances activity for H+ reduction. A high H2 yield rate of 181 μmol h-1 cm-2 (equal to 580 mmol h-1 g-1 based on the loading mass of MoS2) is achieved using a low catalyst loading mass.
The spatially uniform heterostructure, correlated to plasmon-resonance through conformal coating MoS2 that effectively regulated charge transfer pathways, is proven to be vitally important for the unique solar energy harvesting and photocatalytic H2 production.—Guo et al.
Fabricating the catalyst is relatively easy and inexpensive. Yang’s team is continuing its research by focusing on the best way to scale up the fabrication, and further improve its performance so it’s possible to split hydrogen from wastewater.
Limin Guo, Zhenzhong Yang, Kyle Marcus, Zhao Li, Bingcheng Luo, Le Zhou, Xiaohui Wang, Yingge Du and Yang Yang (2017) “MoS2/TiO2 Heterostructures as Nonmetal Plasmonic Photocatalysts for Highly Efficient Hydrogen Evolution” Energy & Environmental Science doi: 10.1039/C7EE02464A