The electrolyte pH has been determined to be an important factor that has a direct influence on the formation of film morphologies. Herein, we investigate the effect of electrolyte pH on the formation of nickel oxide (NiO_x) films in borate solutions and examine their corresponding electrochromic characteristics. The result shows that the formation of hexa-aquo Ni complexes due to an appropriate electrolyte pH can aid the electrodeposition of NiO_x films and produce a film of small grains. Raman and in situ X-ray absorption fine structure (XAFS) measurements indicate that the structure of the NiO_x films in their oxidized state is similar to γ-NiOOH, regardless of the electrolyte pH, although the grain size of the films is dependent on the electrolyte pH. The different grain size results in significant differences in electrochromic performance. The film made of small grain size exhibits the best electrochromic performance. The optical contrast of the NiO_x film achieved 87%. The coloration efficiency increased by about 50% to 51 cm²/C and the switching time reduced to 5.4 s for bleaching. These results demonstrate the imperative for an appropriate electrolyte pH to enable sustained electrochemical activity, reactive site formation, and functional stability.

已经确定电解质的pH是直接影响膜形态形成的重要因素。在本文中，我们研究了电解质pH值对硼酸盐溶液中氧化镍（NiO _x）膜形成的影响，并研究了其相应的电致变色特性。结果表明，由于适当的电解质pH而形成的六水合Ni络合物可以帮助NiO _x膜的电沉积并产生小晶粒的膜。拉曼和原位X射线吸收精细结构（XAFS）测量表明，NiO _x的结构尽管电解质的pH值取决于薄膜的粒径，但无论电解质的pH值如何，处于氧化态的薄膜都类似于γ-NiOOH。不同的晶粒尺寸导致电致变色性能的显着差异。小粒径的薄膜具有最佳的电致变色性能。NiO _x膜的光学对比度达到87％。着色效率提高了约50％，达到51 cm ² / C，漂白时间缩短到5.4 s。这些结果表明，必须有合适的电解质pH值才能实现持续的电化学活性，反应位点形成和功能稳定性。