Publication: Comparison between oxide formed on pure ti, pure ni and tini alloys for photocatalytic hydrogen generation application
Date
2024-08-01
Authors
Tan Zi Wei
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Abstract
Hydrogen energy has emerged as a promising and sustainable solution to address current energy challenges and future environmental concerns. The preparation of photoanodes for photoelectrochemical (PEC) applications involves addressing challenges such as light absorption and charge separation within the semiconductor, as well as the charge transfer across the semiconductor–electrolyte interface. This study focuses on Ti-Ni alloy photoanodes with various Ni content aim to get NiO-TiO2 P-N junction in the surface.to enhance the photoconversion performance. Ti-Ni alloy samples were prepared using powder metallurgy and formed into pellets (with varying Ni content: 10, 25, and 50%). Then, the pellets were anodized in ethylene glycol + 5vol% H2O + 0.7wt% NH4F or Na2CO3 for one hour to synthesize nanotubes on the surface. The anodized pellets were annealed for three hours to promote the crystallization of oxide phases. The samples were characterized using FESEM and HR-TEM for nanostructure analysis, XRD, Raman Spectroscopy, and XPS for phase studies, PL Spectroscopy for semiconductor properties and ICP-MS for dissolution studies during anodization. Sample for anodized Ti-10Ni with ethylene glycol + 5vol% H2O + 0.7wt% NH4F in 1 hour anodizing duration showed successful formation of nanotubular structures, although nickel dissolution occurred greatly during the anodization. Phase analysis confirmed the presence of mixed oxides, and PL spectroscopy showed that the introduction of Ni reduces the recombination of electron-hole pairs. The optimized photoanodes exhibited enhanced PEC performance, with the Ti-10Ni sample showing the greatest photocurrent density, 4.03 mA/cm² at 0.6V versus Ag/AgCl in 1.0M KOH. This study demonstrates that Ti-Ni alloy photoanodes with the formation of NiO-TiO2 through anodization are a cost-effective and promising clean renewable source for water-splitting applications.