Spherical Carbon Derived from Sustainable Sources and Decorated with Silver Nanoparticles as a Catalyst for Hydrogen Release

TL;DR

This paper presents a sustainable catalyst made from spherical carbon and silver nanoparticles that efficiently releases hydrogen from a storage material.

Contribution

The study introduces a novel catalyst using glucose-derived carbon and silver nanoparticles for efficient hydrogen release.

Findings

AgSC showed superior catalytic activity with high hydrogen generation under neutral pH and elevated temperatures.

The catalyst had an activation energy of 54 kJ mol−1 and high turnover numbers and frequencies.

AgSC retained ~95% activity after five cycles, showing good reusability.

Abstract

The reliance on carbon-based fuels remains a major contributor to greenhouse gas emissions, emphasizing the need for sustainable alternatives such as hydrogen. Sodium borohydride (NaBH4), with a hydrogen content of 10.6 wt%, is a promising chemical hydrogen storage material capable of releasing four moles of H2 per mole through hydrolysis; however, effective catalysts are essential for practical implementation. In this study, silver nanoparticles supported on glucose-derived carbon microspheres (AgSC) were synthesized and evaluated for catalytic NaBH4 hydrolysis. Structural characterization (XRD, TEM, SEM, EDS) confirmed the uniform dispersion of metallic silver nanoparticles on the carbon support with no detectable Ag2O phase. AgSC exhibited superior catalytic activity compared to unsupported Ag or bare carbon, achieving the highest hydrogen generation under neutral pH, elevated temperatures, and 835 µmol NaBH4. The catalyst displayed an activation energy of 54 kJ mol−1, turnover numbers (TONs) of 1.4 × 105–1.9 × 105, and turnover frequencies (TOFs) of 7.1 × 104–9.3 × 104 h−1, demonstrating efficient utilization of active sites. pH-dependent studies revealed optimal hydrogen yield under neutral conditions, while acidic and basic media reduced performance due to surface poisoning and BH4− stabilization, respectively. Reusability tests showed only ~5% activity loss after five cycles. These findings establish AgSC as a stable, efficient, and recyclable catalyst for on-demand hydrogen generation, supporting sustainable clean fuel technologies.

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