Scientists at the Tata Institute of Fundamental Research (TIFR) in Mumbai have developed a completely new materialthat they call ‘black gold’, formed not by adding other materials or chemicals to the original precious metal gold, but just modifying the amount of space between each gold nanoparticle.
The ‘wonder material’ can potentially be used for applications ranging from solar energy harvesting to desalinating seawater.
The findings have been announced in the journal Chemical Science, published by the Royal Society of Chemistry, media reports said.
“We have not doped gold nanoparticles with any other material or added other materials,” Vivek Polshettiwar, who led the research team, told India Science Wire.
“We varied the inter-particle distance between gold nanoparticles using a cycle-by-cycle growth approach by optimizing the nucleation-growth step, using dendritic fibrous nanosilica, whose fibers were used as the deposition site for gold nanoparticles,” he said.
Basically, they sort of “grew” the gold in the exact nanostructure they wanted by laying a silica foundation first. The result is a black material, hence the name black gold.
This black gold has the ability to absorb both light and carbon dioxide, something traditional gold can’t do. This is, thus, an entirely new material.
It can absorb the entire visible and near-infrared region of solar light, “because of inter-particle plasmonic coupling as well as heterogeneity in nanoparticle size”. This makes it perfect for use in high-efficiency solar panels.
Black gold could also act as a catalyst and could convert carbon dioxide 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,” added Polshettiwar.
The conversion from CO2 to fuel is currently low-yield, but the researchers believe it can be improved in future.
Because of its ability to absorb solar energy, the researchers also believe the black gold can be used in portable nano-heaters, which can convert seawater into drinking water.
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.
“Our results indicate the potential application of black gold in the purification of seawater to potable water via steam generation using solar energy under atmospheric reaction conditions,” they said. This could be helpful in mitigating the looming drinking water crisis.
The research team included Mahak Dhiman, Ayan Maity, Anirban Das, Rajesh Belgamwar, Bhagyashree Chalke and Vivek Polshettiwar (TIFT); Yeonhee Lee, Kyunjong Sim and Jwa-Min Nam (Seoul National University). The study was funded by the Department of Science and Technology (DST) and the Department of Atomic Energy (DAE).