Synthesis of Pt mesoflowers as electrocatalysts for water splitting

Electrocatalytic water splitting is considered a hopeful technology in the production of hydrogen as affordable green energy. Electrocatalysts are used to enhance the electrokinetics of the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Compared to other noble metals, platinum (Pt) has the highest efficiency and stability in HER electrocatalyst in acid or base electrolytes. Literature studies show that the electrocatalytic efficiency of nanostructured Pt is greatly affected by the shape, size, and surface of the crystal facets. For this reason, this research carried out the synthesis of Pt particles on a glass substrate coated with indium tin oxide (ITO) using square-wave pulse (SWP) electrodeposition with two variations in the electrolyte solution (KCl and KCl+H₂SO₄) to obtain certain crystal facets on the surface. The results show that the growth of Pt particles was affected by the presence of certain ions in the sulfuric acid electrolyte (HSO_4⁻ and SO₄^2-). These ions promoted the formation of anisotropic, flower-like particles, while using KCl by itself as an electrolyte produced only spherically shaped Pt particles. Our Pt mesoflowers (MFs) showed better catalytic performance in the HER and a lower overpotential and slope than the Pt mesospheres (MSs). This result might be due to the presence of the high-index facets (220) and (311), which work as active sites that can break the bonding chains of compounds. On the other hand, the dominant crystal facets of the Pt MSs are (100) and (002), which are more favorable for the catalytic activity of the OER.