Large-scale stationary hydrogen storage is critical if hydrogen is to fulfill its promise as a global energy carrier. While densified storage via compressed gas and liquid hydrogen is currently the dominant approach, liquid organic molecules have emerged as a favorable storage medium because of their desirable properties, such as low cost and compatibility with existing fuel transport infrastructure. This perspective article analytically investigates hydrogenation systems' technical and economic prospects using liquid organic hydrogen carriers (LOHCs) to store hydrogen at a large scale compared to densified storage technologies and circular hydrogen carriers (mainly ammonia and methanol). Our analysis of major system components indicates that the capital cost for liquid hydrogen storage is more than two times that for the gaseous approach and four times that for the LOHC approach. Ammonia and methanol could be attractive options as hydrogen carriers at a large scale because of their compatibility with existing liquid fuel infrastructure. However, their synthesis and decomposition are energy and capital intensive compared to LOHCs. Together with other properties such as safety, these factors make LOHCs a possible option for large-scale stationary hydrogen storage. In addition, hydrogen transportation via various approaches is briefly discussed. We end our discussions by identifying important directions for future research on LOHCs.

We estimate the energies of intrinsically coupled (0001)-Zn/O faces of wurtzite ZnO using a heterojunction model.

Modern quantum chemical electronic structure methods typically applied to localized chemical bonding are developed to predict atomic structures and free energies for meso-tetraalkylporphyrin self-assembled monolayer (SAM) polymorph formation from organic solution on highly ordered pyrolytic graphite surfaces. Large polymorph-dependent dispersion-induced substrate−molecule interactions (e.g., −100 kcal mol⁻¹ to −150 kcal mol⁻¹ for tetratrisdecylporphyrin) are found to drive SAM formation, opposed nearly completely by large polymorph-dependent dispersion-induced solvent interactions (70–110 kcal mol⁻¹) and entropy effects (25–40 kcal mol⁻¹ at 298 K) favoring dissolution. Dielectric continuum models of the solvent are used, facilitating consideration of many possible SAM polymorphs, along with quantum mechanical/molecular mechanical and dispersion-corrected density functional theory calculations. These predict and interpret newly measured and existing high-resolution scanning tunnelling microscopy images of SAM structure, rationalizing polymorph formation conditions. A wide range of molecular condensed matter properties at room temperature now appear suitable for prediction and analysis using electronic structure calculations. Significance First-principles free energy calculations, characterizing polymorphism of self-assembled monolayers (SAMs) of porphyrin molecules formed from solution onto graphite, are performed using efficient methods previously applied only to small-molecule reactivity. SAM structures are typically optimized in the absence of solvent using density functional theory embodying explicit dispersion corrections. Added then are dispersion-dominated implicit solvation energies and SAM formation entropies derived from both molecular and phonon vibration frequencies. Scanning tunneling microscopy (STM) images are measured, and polymorph formation free energies are approximated. Close parallels between experiment and theory support the hypothesis that the first seconds of SAM formation are under thermodynamic control, despite formed SAMs being kinetically trapped. Polymorphism is associated with large opposing changes to entropy and substrate−molecule and solvent−molecule interaction energies.