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New hybrid photocatalyst for highly efficient hydrogen production from water

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.

Resources

  • 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

Comments

HarveyD

Turning fresh, waste and sea water into H2, using free solar energy, could further reduce the cost of clean H2 for practical-competitive use in FCEVs?

Alternatively, the same/similar process could eventually produce clean e-energy in huge quantities to replace current polluting CPPs and NGPPs?

SJC

Solar is 4-5 hours per day, we need 24/7.

JMartin

Why?

HarveyD

A string of solar sites installed on a new Coasts to Coasts grid could supply H2 and e-energy in huge quantities for an average of 9+ hours/day.

Some of the excess H2 could be mixed with NG to produce cleaner energy or used to feed large FCs to produce energy outside solar plants production hours.

Of course, a few more thousand larger wind mills installed on higher towers would/will also help.

Lighter Electrified vehicles being 2X to 3X times more efficient than current heavy ICEVs would use less energy. Electric airplanes and trains are also more efficient and could contribute to higher ernergy usage efficiency?

Up-to-date higher efficiency heat pumps could replace current low efficiency furnaces/heaters and AC to further reduce e-energy consumption.

SJC

No, we have three time zones that still give 4 hours each. You are not going to transport H2 across time zones, that makes no sense. Use renewable power contracts, those work 24/7 with the grid.

HarveyD

Come on SJC. H2 and e-energy (electricity) could be produced alone the way (from East to West Coast), in each time zone and more and distributed as required.

NG, Oil and Coal will not last forever but the Sun will probably be there for another few billion years.

SJC

Capital investment wants to be paid back ASAP 24/7.

HarveyD

The alternative may be to continue to pay for weather related disasters at an increasing rate from $250B to $1,000B/year?

SJC

No, situations where this makes sense maybe.
Coal causes sickness and death but they never paid for that.

HarveyD

Eventually, a class action will be used to support (and win) a huge claim against polluters from Coal mines, oil refineries, tar snds operations, CCPs, ICEVs manufacturers and end users?

The $30B that VW is paying for ceating is peanuts.

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