Effect of pH on Hydrothermal Synthesis of ZrO2 Nanoparticles and their Electrocatalytic Activity for Hydrogen Production

Electrolytic hydrogen production needs heavy-duty electrocatalyst to lower the overpotential to economical values. With this respect, we scrutinized the effect of pH on the phase formation, microstructure and hydrogen production activity of ZrO2 generated under hydrothermal processing. At both low and high pHs (2.61 and 14) the products are single phase monoclinic ZrO2. However, at intermediate pHs (7.0-11.0), the produces are biphasic mixture of tetragonal and monoclinic nano crystallites. The particles size slightly increases (from 11 to 14 nm) with increasing the pH up to 11. However, at pH=14.0, the particle size abruptly increases to 98 nm. The vibration spectra demonstrated that monoclinic ZrO2 comprise intense surface hydroxyl functional groups, that enhance the electrocatalytic activity of ZrO2 nanoparticles. Thus, the hydrogen evolution activity increases with increasing the monoclinic phase contents. Zr02 produced at low pH (2.61) showed the highest electrocatalytic activity.