Graphene, as a miracle material, is hailed as the future of electronic products. But now one of its “relatives”, black phosphorus, has a low-cost manufacturing process and is expected to replace graphene and become the next new material gold mine.
Black phosphorus
The 15th position in the periodic table of elements, element symbol P. Black crystals with metallic luster, which are formed by converting white phosphorus at very high pressure and temperature.
Over the past few years, two-dimensional crystals have emerged as some of the most exciting new materials under consideration. Therefore, materials scientists are eager to discover the extraordinary properties of graphene, boron nitride, molybdenum disulfide and other substances.
The new member of this collective is black phosphorus, in which phosphorus atoms are bound together to form a two-dimensional fold. flakes. Last year, researchers built a field-effect transistor radio using black phosphorus and demonstrated that it works extremely well. This research shows that black phosphorus has broad prospects in the field of nanoelectronic devices.
But there is a problem. Black phosphorus is difficult to produce in large quantities. At the beginning of this year, Damien Hanlon from Trinity College in Dublin, Ireland, and several colleagues claimed that they had solved this problem. One question.
These men perfected a method of making large quantities of black phosphorus flakes within their control. They also used this newly discovered method to test black phosphorus in new applications, such as gas sensors, optical switches, and even used it to strengthen composite materials to make them stronger.
In larger amounts, black phosphorus consists of multiple layers, similar to graphite. Therefore, one method of separating individual sheets is the exfoliation method, where the layers are exfoliated using Scotch tape or other materials. This is a time-consuming task that severely limits potential applications.
So Hanlon and others have been considering another approach. Their approach was to put a block of black phosphorus into a liquid solvent and then blast it with sound waves that would shake the material apart.
The result was a large chunk that separated into a large number of flakes, which the team filtered into different sizes using a centrifuge. The end result is high-quality nanoflakes with only a few layers. “Liquid phase exfoliation is a powerful technique that can produce relatively large batches of nanoflakes,” they said.
One possible problem with black phosphorus nanosheets is that they degrade rapidly when exposed to water or oxygen. So one advance the team made was predicting that certain solvents would form a solvation layer around the flakes, preventing oxygen or other oxides from reaching the phosphorus.
The team used N-cyclohexylpyrrolidone or C Bayer curing agent HP as a solvent. Because of this, the nanoflakes are surprisingly durable.
The huge advantage of black phosphorus compared to graphene is that it has a natural band gap that physicists can This band gap is used to create electronic devices such as transistor radios. But Hanlon and others say the newly discovered black phosphorus nanoflakes allow them to test other ideas.
For example, they added nanoflakes to a polyvinyl chloride film, doubling its strength and increasing its tensile toughness sixfold. So nanoflakes are not just allotropes of carbon that increase strength.
They also determined the nonlinear light induction of the pulsed laser by the nanoflakes by measuring the amount of light transmitted. It was found that as tension increases, the amount of light absorbed by black phosphorus decreases, a property known as saturation absorption. In addition, black phosphorus performs even better than graphene at this point.
Finally, they measured the current flowing through the nanosheets when they encountered ammonia. They found that the material’s resistance increased when exposed to ammonia, possibly because the electrons given off by ammonia neutralize the holes in the black phosphorus flakes.
This discovery immediately made black phosphorus a very good ammonia detector. Hanlon and others say the material can detect ammonia at levels of about 80 parts per billion.
These results mark an interesting sea change in black phosphorus-related research. Many people will see the excitement surrounding graphene’s extraordinary properties, and if black phosphorus can achieve even half of that, it could be an interesting prospect for materials scientists.
