Galvanic displacement reaction of nickel to form one-dimensional trigonal tellurium structures in acidic solutions

Abstract

Trigonal tellurium micro-wires and tubes were synthesized by galvanic displacement of nickel in acidic sulfate solutions where the growth mechanism was elucidated using various electroanalytical methods and material characterization. The effects of solution composition, including concentrations of tellurium precursor and sulfate, were studied. The transition from micro-wires to tubes with an increase in HTeO2+ concentration was observed, which might be attributed to the comparable diffusion length scale of tellurium on the cylindrical seed surface to the radius of the seed. On the other hand, increasing H2SO4 concentration led to transformation of microtubes to microwires owing to reduction deposition rate and limited mass transfer of HTeO2+ ions. The effect of other anions (i.e., Cl− and NO3−) on galvanic displacement reaction was also studied. As a strong oxidant, HNO3 dissolved nickel faster than SO4−2 and Cl−, but showed slower tellurium deposition tellurium nanowires, which might be due to co-reduction of nitrate ions. The preferential adsorption of Cl− increased both dissolution of nickel and the deposition of tellurium, resulting in larger tellurium microtubes.