Surface engineering of non-platinum-based electrocatalysts for sustainable hydrogen production: Encapsulation, doping, and decoration approach

Abstract

The hydrogen evolution reaction's electrocatalytic reduction of water to molecular hydrogen may one day provide a long-term sustainable source of energy. However, the use of precious platinum catalysts makes it difficult to commercialize. So far, all alternatives to platinum are based on non-precious metals and transition metals. Hence, tuning the catalytic activity of nanomaterials through surface engineering might offer significant advantages. Herein, we step-wisely modulate the surface of all carbon fullerene nanomaterial by encapsulation, doping and decoration with alkali and transition metals to produce a hybrid catalyst which demonstrated excellent hydrogen evolution activity with comparable Gibbs free energy with both experimentally developed and theoretically modelled electrocatalyst. The adsorption of H* intermediate on the doped and decorated metal sites has been investigated in comparison with the pristine C24 fullerene structure. The electronic properties, the density of state (PDOS), reaction-free energy (ΔG) and transition states have all been carefully considered at appropriate theoretical levels. The ΔG of hydrogen adsorption on H@IndecNidopMgencC24 was found to be closer to zero (0.0328 eV) because of the concomitant effect of the encapsulation, doping and decoration with transition metals thus, demonstrating the effectiveness of this approach to tuning catalytic activity. The encapsulated metal enhanced the catalyst surface's conductivity and electronic attributes, leading to improved HER activity. The catalytic HER was also found to follow the Volmer-Tafel pathways, resulting in a lower free energy barrier. Overall, this work demonstrates a simple structure-activity relationship between metallic effects and substrate engineering and could open new dimensions for the development of novel non-platinum-based electrocatalysts.