Study: Single-crystal nanowires of niobium arsenide may replace copper wires

Niobium arsenide cannot replace copper in wires or cables, for two reasons, it is many times more expensive and it is fragile, so it cannot bend.

Moreover, at normal sizes it is not a better conductor than copper, so it would have no advantage anyway.

According to this research, it could replace copper for one or for a few conducting layers inside an integrated circuit, those with the finest pitch, while the thick conducting layers used for carrying great currents would remain of copper.

The toxicity of arsenic is irrelevant. Only extremely small quantities are necessary and they are sealed inside the integrated circuit. Almost all integrated circuits already contain arsenic, as it is the best N-doping element for silicon (because the size of the arsenic atoms is better matched with the size of silicon atoms than the sizes of phosphorus or antimony atoms).