Single tungsten nanowires as pH sensitive electrodes

This study explores the development and characterization of single tungsten nanowires as pH-sensitive electrodes, demonstrating the applicability of tungsten oxide in the nanoregime for pH detection. The researchersprepared these nanowire samples, typically 100-200 nm in diameter and covered with their native oxide, through a meticulous process involving selective etching of a directionally solidified NiAl-W eutectic alloy. This fabrication method allowed for the precise control of nanowire dimensions and subsequent electrochemical modification to optimize their pH sensing capabilities. The methodological approach involved measuring the electrochemical potentials by monitoring the open circuitpotential of the nanowire electrodes across various pH values and comparing their performance to macroscopic tungsten oxide samples. The key contribution is the successful demonstration of tungsten oxide's pH sensitivity at the nanoscale,with the production method advanced beyond the prototype stage to enable gram-scale manufacturing. This work highlights the significant potential for further miniaturization and the use of these nanowire pH probes in confined environments like corrosion pits or biological cells.