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[Display omitted] • Four-step strategy for selecting dopants based on binding energy. • Proposing Cu and Au-doped CNTs as promising candidates at near ambient temperatures. • Achieving the DOE target for gravimetric capacity with 5–6% impurity in Cu-doped SWCNTs. • Analyzing hydrogen storage performance of CNTs with various copper cluster sizes. • Strategy evaluation, desorption temperatures and gravimetric capacities of excluded dopings. Identifying a nanostructure suitable for hydrogen storage presents a promising avenue for the secure and cost-effective utilization of hydrogen as a green energy source. This study introduces a systematic approach for selecting optimal doping on porous materials, emphasizing the intricate interplay between doping with the material's structure and the interaction between doping and hydrogen. Our proposed approach serves as a framework for evaluating and predicting the performance of doped materials. To validate the efficacy of our strategy, we conduct a comprehensive investigation in carbon nanotubes (CNTs). Applying our criteria, we systematically screen several dopants in CNTs. The results highlight Cu-doped CNTs as promising candidates for hydrogen storage applications. Focusing on Cu-doped CNTs, we analyze binding energy, charge transfer, partial density of states (PDOS), and desorption temperature to assess the performance of modified CNTs. Additionally, we explore the feasibility of doped CNTs featuring various sizes of copper clusters and the effect on the release temperature, i.e., complete regeneration. The findings indicate that incorporating 5 to 6% copper impurity onto CNT surfaces renders these nanostructures highly applicable for reversible hydrogen storage near ambient conditions. [ABSTRACT FROM AUTHOR]

In a world where capture and separation processes represent above 10% of global energy consumption, novel porous materials, such as Metal-Organic Frameworks (MOFs) used in adsorption-based processes are a promising alternative to dethrone the high-energy-demanding distillation. Shape and size tailor-made pores in combination with Lewis acidic sites can enhance the adsorbate-adsorbent interactions. Understanding the underlying mechanisms of adsorption is essential to designing and optimizing capture and separation processes. Herein, we analyze the adsorption behaviour of light hydrocarbons (methane, ethane, ethylene, propane, and propylene) in two synthesized copper-based MOFs, Cu-MOF-74 and URJC-1. The experimental and computational adsorption curves reveal a limited effect of the exposed metal centers on the olefins. The lower interaction Cu-olefin is also reflected in the calculated enthalpy of adsorption and binding geometries. Moreover, the diamond-shaped pores' deformation upon external stimuli is first reported in URJC-1. This phenomenon is highlighted as the key to understanding the adsorbent's responsive mechanisms and potential in future industrial applications. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • Gold-doped carbon-based structures for hydrogen storage. • Effect of a single atom and small nanocluster formation on the performance. • Maximum volumetric and gravimetric capacity about 5 wt% and 300 g/l for Au-CNT. • Reversible hydrogen storage-release near room conditions. Hydrogen as a clean energy source is receiving great attention, and over-ground storage using porous materials has been identified as a promising alternative to current solutions. The general disadvantage is the relatively weak solid–gas interaction and adsorption energy, providing low gravimetric and volumetric capacities and extreme operational conditions. Here we propose Au-doped carbon nanotubes (CNTs) as an efficient alternative for reversible hydrogen capture at high temperatures. This work investigates the properties of several modified CNTs using density functional theory. We analyze the binding and formation energies of the uniformed Au-doped CNTs and assess their adsorption capability. The hydrogen storage mechanisms of the nanostructures are studied in depth using partial density of states and charge transfer analysis showing that the increase of diameter has a positive effect on the outcome. Our findings show that the modified structures are able to capture from six to nine hydrogen molecules per gold atom, achieving volumetric capacities ranging from 154 to 330 g/l, surpassing the DOE target. In addition, the calculated desorption temperatures indicate high performance of Au-doped CNTs, obtaining hydrogen capture-release working conditions above 200 K. [ABSTRACT FROM AUTHOR]

• CO 2 /CH 4 selective adsorption in Metal Organic Frameworks (MOFs) was analyzed. • Computational screening of 3000 MOFs structures from CoREMOF database. • Selection of 13 MOFs with highest selectivity (>80 in dry and humid conditions) • Structures performing best in dry or in humid environment identified. • Competition between water and CO 2 adsorption observed and discussed. Competitive adsorption of water is an important issue in the adsorption-based industrial processes of bio- and flue gases separation. The dehumidification of gases prior to separation would increase process complexity and lower its economic interest. In this work, large-scale computational screening was applied to identify Metal-Organic Frameworks (MOFs) structures which exhibit high CO 2 /CH 4 selectivity and total loading higher than 0.5 mol/kg (in the presence of water). High-throughput Grand Canonical Monte Carlo (GCMC) screening of nearly 3000 existing MOF materials was carried out. Initial selection assumed fixed values of pore limiting diameter (PLD) and Henry's constant for water and allowed one to preselect 764 structures. After GCMC simulations carried for 50/50 CO 2 /CH 4 mixture, at ambient conditions (p = 1 bar, T = 298 K), and variable gas humidity (0%, 5%, 30% and 40%) the final selection revealed 13 most promising MOFs structures. We focused on analysis of the correlations between the properties of the selected MOFs and the separation selectivity. We show that the selectivity is a complex function of the porous materials characteristics and finding selective sorbent, performing well in dry and wet conditions requires careful analysis of available MOFs. [ABSTRACT FROM AUTHOR]