Synergetic action of 0D/2D/3D N-doped carbon nanocages and NbB2 nanocatalyst on reversible hydrogen storage performance of lithium borohydride
Yuxiao Jia, Panpan Zhou, Xuezhang Xiao, Xuancheng Wang, Bo Han, Jianchuan Wang, Fen Xu, Lixian Sun, Lixin Chen
Abstract
A synergetic approach of nanoconfinement coupling with in-situ formed nanocatalysts was developed to fabricate a novel and robust nano-LiBH 4 system. The nanoconfining scaffold exhibits an unparalleled 3D hierarchical architecture featuring micro-, meso-, and macro-pores assembled by 2D interconnected nanosheets that consist of 0D hollow nitrogen-doped carbon nanocages. This structure possesses an accumulated pore width of 7.79 nm, extremely high pore volumes of 3.16 cm 3 /g, and a theoretical loading capacity of 67.9 wt% for LiBH 4 . The in-situ formed NbB 2 species transformed from initial NbF 5 nanoparticles is confirmed as the final active nanocatalyst. It is worth mentioning that the defective N heteroatoms within the scaffold can serve the role of coordinating with Nb cations and weaken the B-H bonds as supported by the DFT calculations. With an optimized loading of 50 wt% LiBH 4 , the initial dehydrogenation temperatures can be reduced to 140.6 °C, and the system can rapidly release 7.55 wt% H 2 at 320 °C within 39 min. Furthermore, the nanoconfined system exhibits excellent low-temperature reversibility, retaining 93 % of its capacity after 20 cycles at 300 °C. This study provides innovative perspectives on the design of novel scaffold structures doped with defective heteroatoms for the nanoconfinement and synergetic catalysis of de/rehydrogenation for metal borohydrides.