Hydrogen Storage: A Nano Sorbent Development, Capacity Assessment, and Structure-Property Relationship Investigation

Abstract

The increased consumption of fossil fuels for energy production has led to higher greenhouse gas emissions, necessitating sustainable, low-carbon energy solutions. Efficient hydrogen storage plays a crucial role in this transition, offering promise for energy storage applications. Adsorption-based storage gas (AGS) systems can reduce high-pressure requirements, and improve energy density, cyclability, and system efficiency. However, conventional hydrogen storage technologies face challenges related to cost, safety, and efficiency. This dissertation aims to develop high-performance nanoporous adsorbents optimized for hydrogen uptake and delivery, addressing these limitations. The goal is to meet the Department of Energy&rsquo;s 2025 hydrogen storage targets of 40 g/L volumetric and 5.5 wt.% gravimetric capacity with intermediate binding energies (&Delta;H = 15&ndash;25 kJ/mol). This research focuses on three key objectives: (1) developing advanced nanoporous sorbents, (2) assessing hydrogen storage capacity under different conditions, and (3) investigating the structure-property relationships for optimizing material performance.&nbsp;Key challenges for AGS technologies include low room-temperature capacities, stability, and efficiency over repeated cycling. This work explores the synthesis and functionalization of advanced nanoporous materials to balance gravimetric and volumetric storage capacities, focusing on working capacities, adsorption-desorption kinetics, binding strength, packing density, and cyclic stability. The dissertation is organized into three phases: (1) enhancing gravimetric storage in activated carbon (AC) at reduced pressures, (2) improving volumetric capacities in metal-organic frameworks (MOFs) through densification, and (3) optimizing graphitic carbon nitride (g-C3N4) for hydrogen storage via combined physisorption and chemisorption mechanisms.&nbsp;This dissertation enhances the design of nanoporous adsorbents, offering scalable hydrogen storage solutions for a sustainable, low-carbon energy future.</p