Adsorption of urea on metal-functionalized Si nanowires for a potential uremia diagnosis: A DFT study

• Urea is adsorbed on metal decorated silicon nanowires (SiNW). • The metal adatom rises the adsorption energy of urea on the SiNW. • Urea adsorption provokes a significant change in the work function of SiNW. • Charge transfer from urea to the SiNW could change its electrical resistivity. • The largest band gap change upon adsorption is of 0.34 eV, for the pristine case. Uncommon concentrations of urea in the human body could be indicative of uremia, which is a symptom of kidney malfunctioning. In this paper, we investigate the effect of urea adsorption on Ag-, Au-, and Cu-decorated silicon nanowires (SiNW). We considered SiNWs grown along the [1 0 0] direction with (1 1 0) exposed surfaces and passivated with hydrogen. For the metal-decorated SiNWs, an H passivating atom on the SiNW surface is replaced by an Au, Ag, or Cu atom, which is used as adsorption site for the urea molecule. The results show that the metalized SiNWs are capable to adsorb the urea molecule, having the highest adsorption energy for the Cu case, followed by the Ag and Au cases. The adsorption of urea on the metal-decorated SiNW modifies the electronic states inside the valence and conduction bands, this hybridization confirms that the urea molecule is adsorbed by the metalized SiNW. Also, a noticeable change in the work function of the systems, provoked by the urea adsorption, could allow the detection of the molecule. These nanostructures could be used for urea capture and detection, which could lead to a potential nanosensor for the diagnosis of uremia.