Significant Enhancement of Electrocatalytic Activity of Nickel-Based Amorphous Zeolite Imidazolate Frameworks for Water Splitting at Elevating Temperatures

Numerous synthesis strategies have been adopted to promote the electrocatalytic behavior of electrocatalysts for water splitting. Suitable conditions can effectively influence and enhance the electrocatalytic activity. Oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) activities of the Ni4gZIF structure have been characterized at various temperatures. Elevating the temperature removed the energy barriers from the surface of the electrocatalysts. Higher electrical conductivity and increased temperature promoted the adsorption and desorption processes of active atoms on the electrocatalyst surface, which enhanced the electrocatalytic activity of the Ni4gZIF structure. The Ni4gZIF structure showed an overpotential of 224 mV at 80 °C to approach a current density of 10 mA cm–2 for the OER process. The Ni4gZIF structure exhibits a good Tafel slope of 78 mV dec–1 with a turnover frequency of 314.80 ms–1 for the OER process. Similarly, the Ni4gZIF structure exhibits an overpotential of 184 mV at 25 °C, which was improved to 82 mV at 80 °C for the HER process. The Ni4gZIF structure exhibits a good Tafel slope of 83 mV dec–1 at 80 °C for the HER process. The intralayer spacing of the Ni4gZIF structure was increased during stability tests at higher temperatures. UV–visible measurements of supernatant solutions did not show any leaching and colloidal particles after stability tests in 1 M KOH. Results indicate that the Ni4gZIF structure exhibits good electrocatalytic behavior at suitable conditions for water splitting.