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Simple and Scalable Synthesis of Vertically Aligned Anatase Nanowires for Enhanced Photoelectrochemical Performance

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journal contribution
posted on 04.09.2020, 20:15 by Kevin Reilly, Baizeng Fang, Fariborz Taghipour, David P. Wilkinson
Vertically aligned 2.45 μm anatase nanowires were produced via a simple chemical bath deposition technique using a low-cost, easy to handle, water-soluble titanium salt precursor. The nanowires were grown from the substrate surface as layered titanate, and then converted to anatase by calcination. The factors controlling nanowire growth and performance, such as the concentration of HNO3, the amount of H2O2, melamine, and urea, are discussed. It was found that an increase in the concentration of HNO3 could result in a slow rate of hydrolysis, which would effectively reduce homogeneous nucleation in the solution and favor heterogeneous nucleation on the substrate surface, resulting in the growth of long nanowires (i.e., 2.45 μm). It was also noted that an increasing concentration of HNO3 resulted in a slight decrease in the nanowire diameter from 62 to 52 nm due to the adsorption of NO3 onto certain facets of the nanowires, which promotes anisotropic growth. In addition, H2O2, melamine and urea were also found to play important roles in the growth of nanowires. As a representative application, the as-developed TiO2 nanowires were explored as a photoanode, which demonstrated considerably enhanced photoelectrochemical performance compared to the rutile nanorods and P25 TiO2.