The researchers prepared three doped samples using ammonium nitrate quantities of 1.2, 2.4, and 3.6 grams, designated ANT-1, ANT-2, and ANT-3, alongside a control sample synthesized without nitrogen doping. This design allowed the degree of nitrogen incorporation to be varied directly through the amount added during synthesis. Among the doped materials, the lowest dopant loading, ANT-1, outperformed the heavier loadings in the hydrogen evolution tests.

Structural and spectroscopic measurements characterized how the dopant altered the material. X-ray diffraction analysis showed that the anatase phase remained dominant in the doped materials, with a particle size of 25.02 nanometers. Fourier transform infrared spectroscopy revealed a vibration mode close to 500 per centimeter, consistent with the lattice features of the doped oxide. Morphological imaging showed the characteristic one-dimensional order of nanowires, which the authors interpret as evidence of successful anisotropic growth, meaning the crystals elongated preferentially along one direction rather than growing uniformly in all dimensions.

Optical and electrochemical measurements pointed to the electronic effects accompanying the doping. Ultraviolet-visible diffuse reflectance spectroscopy showed a redshift in the absorption profile of the doped nanowires, indicating a reduced electronic bandgap. Electrochemical impedance spectroscopy, which probes how charge carriers move and recombine at an electrode surface, showed the smallest Nyquist semicircle for the ANT-1 sample. The team cites this result as support for improved charge separation in that composition, the sample that also delivered the leading hydrogen yield.

The findings are drawn from laboratory synthesis and characterization of the doped nanowire samples described in the study. The reported 2.2-fold improvement and the 2.6 micromole per square centimeter yield are measured outcomes for these specific compositions and conditions rather than predictions for large-scale devices. Within the series tested, the results identify ammonium nitrate as the nitrogen source used to tune the doping level, and ANT-1 as the composition combining the measured structural, optical, and charge-separation properties with the highest hydrogen evolution among the samples examined.

Subject of Research: Nitrogen-doped titanium oxide nanowires for photocatalytic hydrogen production

Article Title: Strategic engineering of nitrogen-doped titanium oxide with tuned electronic and structural properties for high-efficiency photocatalytic hydrogen production

Article References: Wellia, D. V., Fauziah, D., Djojo, V. M., Putri, Y. E., Wendari, T. P., Ivansyah, A. L., Arramel, A., Kusumawati, Y., & Saepurahman (2026). Strategic engineering of nitrogen-doped titanium oxide with tuned electronic and structural properties for high-efficiency photocatalytic hydrogen production. Journal of Materials Science. https://doi.org/10.1007/s10853-026-13927-x

Image Credits: AI Generated

DOI: 10.1007/s10853-026-13927-x

Keywords: photocatalysis, hydrogen evolution, titanium oxide, nitrogen doping, nanowires, anatase, bandgap, ammonium nitrate, charge separation, X-ray diffraction, electrochemical impedance spectroscopy, materials science