Indian scientists develop 'black gold'

Using gold nanoparticles Indian scientists have developed a new material called “black gold”, which can potentially be used for applications ranging from solar energy harvesting to desalinating seawater, according to a study.

To develop the material, the team from Mumbai-based Tata Institute of Fundamental Research (TIFR) rearranged size and gaps between gold nanoparticles. It has unique properties such as capacity to absorb light and carbon dioxide (CO2), the researchers said.

Gold does not have these properties, therefore ‘black gold’ is being called a new material. In appearance it is black, hence the name ‘black gold’, according to the findings published in Chemical Science journal.

“We have not doped gold nanoparticles with any other material or added other materials. We varied inter-particle distance between gold nanoparticles using a cycle-by-cycle growth approach by optimising the nucleation-growth step, using dendritic fibrous nanosilica, whose fibers were used as the deposition site for gold nanoparticles,” said Vivek Polshettiwar, who led the research team, while speaking to India Science Wire.

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 CO2 into methane at atmospheric pressure and temperature using solar energy.

“If we develop an artificial tree with leaves made out of back gold, it can perform artificial photosynthesis, capturing carbon dioxide and converting it into fuel and other useful chemicals,” Polshettiwar added.

The efficiency of conversion of CO2 into fuel, at present, is low but researchers believe it could be improved in future.

To understand 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.

The material can be used as a nano-heater to covert seawater into potable water with good efficiency, the researchers said.

“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,” according to the researchers. (India Science Wire)

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