Lithium doping in Na-based double perovskite for hydrogen storage and improving their optoelectrronic properties: First-principles investigation

Abstract

The effect of lithium doping on novel double perovskite materials for hydrogen storage has been investigated through first-principles calculation. The lithium doping would cause phase change due to different crystal symmetry. Based on tolerance factors, cohesive energy and Born-Huang criteria, the materials are all stable. The analysis of hydrogen storage properties indicates that lithium doping can both improve the gravimetric storage capacity to 4.41% and 5.08%, and decrease the desorption temperature to 348.7 K and 325.0 K for K2LiScH6 and K2LiAlH6, respectively. And to a certain extent, the introduction of lithium improves the optoelectronic properties especially the photoresponse in ultraviolet region, which demonstrates the applicable potential in photocatalysis. The results are consistent with the wide bandgap values. Our study provides some reference for further experimental studies of double perovskites in hydrogen storage materials.