Effective and environmentally friendly Co nanocatalyst on sodium borohydride hydrolysis in different solvents

Abstract

This study investigates the development and performance of a cobalt (Co) nanocatalyst supported by carbon quantum dots (CQDs) for hydrogen production via sodium borohydride (NaBH₄) hydrolysis. The CQDs were synthesized using a hydrothermal method from caffeine and subsequently used to support the cobalt catalyst. The structure and properties of the synthesized catalyst were characterized using techniques such as X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and energy dispersive spectroscopy (EDX). The catalytic performance was evaluated in various solvents, with the highest hydrogen production rate observed in ethanol. The optimal conditions for Co@CQDs catalyst synthesis were identified as an 8-h hydrothermal treatment with a 3 mmol metal loading. The catalyst demonstrated excellent reusability, maintaining 100% hydrogen production efficiency after seven cycles. The activation energy for the hydrolysis reaction was found to be lower for catalysts synthesized in ethanol (25.48 kJ mol−1) compared to those synthesized in water (35.57 kJ mol−1), indicating enhanced catalytic activity. Under optimum conditions, the hydrolysis reaction in the presence of Co@CQDs (water) catalyst produced 23753 mL min−1 g−1 of hydrogen, while the hydrolysis reaction in the presence of Co@CQDs (ethanol) catalyst produced 28751 mL min−1 g−1. This study highlights the potential of CQDs-supported Co nanocatalysts for efficient and sustainable hydrogen production.