A team of researchers co-led by the City University of Hong Kong and German scholars identified the quantum confinement effect in a photocatalyst of a 3D-ordered macroporous construction.

ScienceDaily report specified that green hydrogen production from solar water splitting had attracted a substantial deal of interest in the past several years as hydrogen is a fuel of high energy density.

Essentially, the quantum confinement impact was discovered to enable the production of hydrogen beneath visible light. The discoveries provide an option for dealing with energy and environmental problems.

The study was co-led by Associate Professor Dr. Ng Yun Hau from CityU's School of Energy and Environment or SEE, and German researchers.

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Science Times - Quantum Confinement in Nano-Photocatalyst: Hydrogen from Solar Water Splitting Contributes Its Production from Green Resources
(Photo: Yshen8 on Wikimedia Commons)
Quantum confinement

Photocatalyst for Solar Water Splitting

An expert in photocatalysis study, Dr. Ng, pointed out that the usual photocatalyst for solar water splitting can absorb ultraviolet light solely from the solar spectrum, accounting for roughly four percent of the energy from sunlight.

On the contrary, a metal oxide photocatalyst called bismuth vanadate or BiVO4, responsive to ultraviolet and visible light, can absorb the energy's maximum of 30 percent in the solar spectrum.

BBC-Edition reported BiVO4 in a so-called 3DOM or 3D-ordered macroporous structure had received substantial attention owing to its optimal performance.

Moreover, this structure's improved photocatalytic activities are frequently attributed to the larger area of the surface, high absorption of light, and "suppressed charge recombination," this study indicated.

Nevertheless, no systematic studies associated the charge transport's impact of highly ordered porous nanostructure on photoactivity.

Dr. Ng, together with his team, took on this particular challenge and examined the unique carrier dynamics of 3DOM and plate-like BiVO4 samples, not to mention their effectiveness in photocatalysis.

Quantum Confinement

Dr. Wu Hao, the first author of the paper, published in the ACS Energy Letters scientific journal, the energy stream leader in the laboratory of Dr. Ng, shared one of the study's highlights.

He explained they discovered that quantum confinement that arises from the ultrathin, crystalline wall of 3DOM BiVO4 raised its conduction band.

It allows photocatalytic protons to decrease to hydrogen beneath visible-light illumination, producing hydrogen from water splitting.

Quantum confinement pertains to changes in optical and electronic properties like energy levels and band gaps when the material's size is decreased to the nanoscale.

Waste-Water Splitting

This research signifies an essential step in understanding charge transport in metal oxide semiconductors, as well as a highly organized porous structure.

The next goal of Dr. Ng, together with his team, is to split wastewater and explore procedures to scale up photocatalytic systems, a similar Phys.org report specified.

Ng explained, Hydrogen generated from solar water splitting is a green process minus any emissions of carbon. He added that they are expecting such technology to have a more extensive application in the future, as there is a high demand for hydrogen from green resources.

Dr. Ng and Dr. Fatwa Abdi, from the Institute for Solar Fuels, Helmholtz-Zentrum Berlin, are the Paper's corresponding authors.

Dr. Hao, Postdoctoral Fellow in CityU's SEE, is the first author of the study. Meanwhile, a postdoctoral in the SEE, Dr. Chung Hoi-ying, also took part in the study.

Related information about quantum confinement in nanoparticles is shown on UW Clean Energy Institute's YouTube video below:


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