Superconductors — materials that carry electricity with zero resistance — usually need either extreme cold or extreme pressure to work. Now a computational study published in Physical Review Letters predicts that a material made of just two stacked layers of boron could superconduct at 68 kelvin (−205 °C) under normal atmospheric pressure: a new upper limit for single-element superconductors.

Boron is a light element with a rich chemistry, and in recent years theorists have focused on 'borophene' — atomically thin sheets of boron. The new study, by researchers in China, examined bilayer borophene, two such sheets stacked together like the layers of graphite. Using first-principles calculations, they found that the stacked structure should host phonon-mediated superconductivity — the classic BCS mechanism — with a transition temperature of 68 K.

That figure would nearly double the previous record for an elemental superconductor. Even more importantly, it would be achieved at ambient pressure, in contrast to hydrogen-rich 'superhydride' superconductors that require crushing pressures of millions of atmospheres.

The mechanism is unusual: the interaction between electrons and lattice vibrations is enhanced in the two-dimensional bilayer, boosting the critical temperature beyond what either single layer could reach. The study establishes bilayer borophenes as the new upper limit for elemental superconducting transition temperatures.

If experiments can confirm the prediction, the material would be a milestone for practical superconductivity — potentially enabling lossless power lines, powerful magnets and more efficient quantum computers at temperatures reachable with relatively simple cooling. For now, the 68 K superconductor exists only in silico — but it gives experimentalists a precise target to shoot for.

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