Indian scientists develop ‘black gold’ that could harvest solar & purify seawater

Indian scientists have tinkered with the chemistry of gold and turned it into ‘black gold’ which they say can be potentially used for applications ranging from solar energy harvesting to desalinating seawater.

Scientists at the Mumbai-based Tata Institute of Fundamental Research (TIFR) used gold nanoparticles and by rearranging size and gaps between them developed a new material which has unique properties such as capacity to absorb light and carbon dioxide. It is black in appearance, hence the name.

Black gold has fascinating properties

One of the most fascinating properties of the new material is its ability to absorb the entire visible and near-infrared region of solar light. It does so because of inter-particle plasmonic coupling as well as heterogeneity in nanoparticle size. Black gold could also act as a catalyst and could convert carbon dioxide into methane at atmospheric pressure and temperature using solar energy.

In order to study solar energy harvesting ability of the new material, researchers dispersed it into water and exposed the solution to light for one hour and the temperature of the solution was measured. The temperature of the solution with pure silica spheres rose to 38 degrees while the ones with different concentrations of black gold rose to 67 to 88 degrees. The maximum increase in temperature was attributed creation of thermal hotspots due to the heterogeneity of the particle sizes as well as optimum inter-particle coupling.

Researchers said the ‘black gold’ can be used as a nano-heater to convert seawater into potable water with good efficiency. “Our results indicate the potential application of black gold in purification of seawater to potable water via steam generation using solar energy under atmospheric reaction conditions,” say the researchers.

This work is a way forward to develop “Artificial Trees” which capture and convert CO2 to fuel and useful chemicals. Although at this stage, the production rate of fuel is low, in coming years, these challenges can be resolved. We may be able to convert CO2 to fuel using sunlight at atmospheric condition, at a commercially viable scale and CO2 may then become our main source of clean energy.

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