(Left) A single copper-doped tungstic acid nanocrystal; (right) Atomic resolution image of the nanocrystal. Credit: Melbert Jeem
Systematic copper doping boosts all-solar utilization in tungstic acid nanocrystals.
Sunlight is an inexhaustible source of energy, and utilizing sunlight to generate electricity is one of the cornerstones of renewable energy. More than 40% of the sunlight that falls on Earth is in the infrared, visible, and ultraviolet spectra; however, current solar technology utilizes primarily visible and ultraviolet rays. Technology to utilize the full spectrum of solar radiation—called all-solar utilization—is still in its infancy.
Research Findings From Hokkaido University
A team of researchers from Hokkaido University, led by Assistant Professor Melbert Jeem and Professor Seiichi Watanabe at the Faculty of Engineering, have synthesized tungstic acid-based materials doped with copper that exhibited all-solar utilization. Their findings were recently published in the journal Advanced Materials.
“Currently, the near- and mid-infrared spectra of solar radiation, ranging from 800 nm to 2500 nm, is not utilized for energy generation,” explains Jeem. “Tungstic acid is a candidate for developing nanomaterials that can potentially utilize this spectrum, as it possesses a crystal structure with defects that absorb these wavelengths.”
A summarized relative light absorption of the tungstic acid crystals ranging from ultraviolet to infrared light. 1, 5, and 10 are the copper concentrations resulting in opto-criticality of the nanocrystals. Credit: Melbert Jeem, et al. Advanced Materials. July 29, 2023
Methodology and Results
The scientists used a photo-fabrication technique they had previously developed, submerged photo-synthesis of crystallites, to synthesize tungstic acid nanocrystals doped with varying concentrations of copper. The structures and light-absorbing properties of these nanocrystals were analyzed; their photothermal, photo-assisted water evaporation, and photo-electrochemical characteristics were measured.
The copper-doped tungsten oxide nanocrystals absorb light across the spectrum, from ultraviolet through visible light to infrared; the amount of infrared light absorbed was greatest at 1% copper doping. 1% and 5% copper-doped nanocrystals exhibited the highest temperature elevation (photothermal characteristic); 1% copper doped crystals also exhibited the greatest water evaporation efficacy, at approximately 1.0 kg per m2 per hour. Structural analysis of the 1% copper-doped nanocrystals indicated that the copper ions may be distorting the crystal structure of tungsten oxide, leading to the observed characteristics when light is absorbed.
Concluding Remarks
“Our discoveries mark a significant advance in advancement in the design of nanocrystallites capable of both synthesizing and harnessing all-solar energy,” concludes Watanabe. “We have demonstrated that copper doping grants tungstic acid nanocrystal a variety of characteristics via all-solar utilization. This provides a framework for further research in the field as well as for the development of applications.”
Reference: “Defect Driven Opto-Critical Phases Tuned for All-Solar Utilization” by Melbert Jeem, Ayaka Hayano, Hiroto Miyashita, Mahiro Nishimura, Kohei Fukuroi, Hsueh-I Lin, Lihua Zhang and Seiichi Watanabe, 29 July 2023, Advanced Materials.
DOI: 10.1002/adma.202305494
This work was supported by Japan Society for the Promotion of Science (JSPS) KAKENHI (20H00295, 21K04823). This work was partly achieved through a supercomputer system at the information initiative center, Hokkaido University. This work was conducted in Hokkaido University, supported by Advanced Research Infrastructure for Materials and Nanotechnology in Japan (ARIM) of the Ministry of Education, Culture, Sports, Science and Technology (MEXT).
How much of the energy of sunlight is in each of those ranges (uv/visible/ir)? Is the IR that we are missing out on a significant chunk?
Please note the second sentence of the first paragraphs says approx 40% of the energy is in the 800 to 2400 nm range. That said, the sentence was a little vague, so if you had a quick query with chatGPT 3.5 you would learn the following: The solar intensity at different wavelengths in the electromagnetic spectrum varies, and it follows a spectrum known as the solar irradiance spectrum. This spectrum represents the distribution of solar energy at different wavelengths emitted by the Sun.
To determine the solar intensity in the range from 800 nm to 2400 nm, we can use data from the solar irradiance spectrum. However, the exact values may vary depending on factors such as atmospheric conditions, location, and time of day. I can provide you with approximate values for solar irradiance at a standard reference condition (often referred to as the “Air Mass 1.5” spectrum) for terrestrial solar energy applications.
Here are some approximate values of solar irradiance in watts per square meter per nanometer (W/m²/nm) for selected wavelengths within the range you specified:
At 800 nm: Approximately 400 W/m²/nm
At 1000 nm (1 micrometer): Approximately 300 W/m²/nm
At 1500 nm (1.5 micrometers): Approximately 100 W/m²/nm
At 2000 nm (2 micrometers): Approximately 40 W/m²/nm
At 2400 nm (2.4 micrometers): Approximately 20 W/m²/nm
These values are approximate and can serve as a general reference for the solar intensity in the specified wavelength range. Actual solar irradiance values can vary depending on location, time of day, and atmospheric conditions. For precise data, you may want to consult solar irradiance databases or resources provided by relevant scientific organizations or agencies.
User
And also what is the approx W per square meter for the visible portion of sunlight?
ChatGPT
The visible portion of sunlight spans roughly from 400 nanometers (nm) to 700 nm in terms of wavelength. The solar irradiance in the visible range of the electromagnetic spectrum can vary somewhat depending on various factors like location, atmospheric conditions, and time of day. However, I can provide you with approximate values for solar irradiance in the visible spectrum under standard reference conditions (often referred to as the “Air Mass 1.5” spectrum) for terrestrial solar energy applications.
Here are approximate values of solar irradiance in watts per square meter per nanometer (W/m²/nm) for selected wavelengths within the visible range:
At 400 nm (violet-blue range): Approximately 1000 W/m²/nm
At 500 nm (green range): Approximately 1000 W/m²/nm
At 600 nm (yellow-orange range): Approximately 800 W/m²/nm
At 700 nm (red range): Approximately 400 W/m²/nm
Again, please note that these values are approximate and can serve as a general reference for the solar intensity in the visible portion of sunlight. The actual solar irradiance values can vary depending on factors like location, time of day, and atmospheric conditions. For precise data, you may want to consult solar irradiance databases or resources provided by relevant scientific organizations or agencies.
Emanual , please if you type into chatgpt3.5 the exact sentence you asked in the comments. Emmanuel Crisp, you might get something similar to the following …. How much of the energy of sunlight is in each of those ranges (uv/visible/ir)? Is the IR that we are missing out on a significant chunk?
ChatGPT
The energy distribution of sunlight across different portions of the electromagnetic spectrum can be described in terms of the spectral power distribution or spectral irradiance. The UV (ultraviolet), visible, and IR (infrared) portions of sunlight each contribute to the total solar energy, but their relative contributions can vary depending on factors such as the time of day, location, and atmospheric conditions. Here’s a general breakdown of the energy distribution:
Ultraviolet (UV) Range (typically below 400 nm):
UV radiation carries a relatively small portion of the total solar energy, typically less than 10%.
While UV radiation is important for processes like photosynthesis and vitamin D synthesis, it accounts for a smaller fraction of the overall energy received on Earth’s surface.
Visible Range (400 nm to 700 nm):
The visible portion of sunlight carries the majority of the solar energy, typically around 40-50%.
This is the range of light that our eyes are sensitive to, and it plays a crucial role in driving photosynthesis in plants.
Infrared (IR) Range (700 nm to 1 mm and beyond):
The IR portion of sunlight carries a significant amount of energy, often comprising around 40-50% of the total.
This energy is primarily responsible for warming the Earth’s surface and plays a crucial role in the Earth’s energy balance.
So, while the UV range carries a relatively small fraction of the energy, both the visible and IR ranges are significant contributors. The IR portion is not a “missed” chunk of energy; rather, it’s a crucial component of the solar energy spectrum that contributes to heating the Earth and maintaining its temperature.
The exact proportions can vary based on location, time of day, and atmospheric conditions. It’s also worth noting that some specialized applications may harness specific parts of the spectrum (e.g., solar panels for electricity generation primarily capture visible light), but in terms of the overall energy balance on Earth, all three ranges (UV, visible, and IR) are important.