Morphological and Surface Electronic Structure Design of Alloys Electrocatalyst for Alkaline HER

Abstract

Among the various hydrogen production methods, water electrolysis provides numerous advantages, including high purity of the produced hydrogen and low carbon emission. In this context, one of the concerns is associated with the replacement, or partial replacement, of noble-metal electrocatalyst for hydrogen evolution reaction (HER) by low-cost, commercially viable ones. To achieve this objective, alloying provides a direct way to tailor the electronic structure of active site and hence is expected to effectively reduce the usage of noble metal. Furthermore, increasing the surface area through morphology design is considered a promising method for enhancing catalyst activity. Among the diverse strategies to increase the surface area, dealloying plays a unique role by generating porous structure, thereby offering advantages in terms of cost-effectiveness and controllable structure. In this study, we have synthesized various Zn-Ni based alloy electrocatalysts using a facile solvothermal method, followed by a dealloying process. Scanning electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and inductively coupled plasma mass spectrometry are used to examine the morphology, composition, and electronic structure. The electrochemical performance is investigated using linear sweep voltammetry, electrochemical impedance spectroscopy, cyclic voltammetry, and electrochemical specific surface area analyses. We demonstrate that resulting HER alloy electrocatalyst exhibits a low overpotential and Tafel slope, and good stability over 200 hours.