Correction to: J Mater Sci (2020) 55:14401–14414 https://doi.org/10.1007/s10853-020-04995-8

We regret an error in the original article regarding some units for the amount of Ni(NO3)2 · 6 H2O and urea used for the precursor solutions. The second sentence of the Experimental section should read: Therefore, 8.00 g or 7.12 g Ni(NO3)2 · 6 H2O (98%, Alfa Aesar) were completely dissolved in 5.1 mL ethanol (≥ 99.9%, Roth) or 8.0 mL acetone (≥ 99.5%, Roth), respectively, and were allowed to rest overnight, before 0.5508 g or 0.4902 g urea (≥ 99.5%, Sigma Aldrich) were added, respectively, to establish a molar ratio of 1/3 between the nickel and urea and were allowed to rest overnight, again.