Transition metal Ti coated porous fullerene C24B24: Potential material for hydrogen storage. (14th December 2015)

• Record Type: Journal Article
• Authors: Tang, Chunmei; Chen, Shengwei; Zhu, Weihua; Kang, Jing; He, Xiang; Zhang, Zhenjun
• Is Part Of: International journal of hydrogen energy. Volume 40:Number 46(2015)
• Page Start: 16271
• Page End: 16277
• Publication Date: 2015-12-14
• Subjects: Fullerene -- C24B24 -- Hydrogen storage -- Density functional theory; Hydrogen as fuel -- Periodicals; Hydrogène (Combustible) -- Périodiques; Hydrogen as fuel; Periodicals; 665.81
• DOI: 10.1016/j.ijhydene.2015.05.159
• Languages: English
• ISSNs: 0360-3199

Abstract

Abstract: The hydrogen storage capacity of transition metal Ti atoms decorated porous fullerene C24 B24 is investigated by the pseudopotential density functional method. The C24 B24 cage contains six B4 rings with the average diameter of 3.88 Å. The Ti atoms are strongly bound to six B4 rings. Each Ti atom can adsorb up to six H2 molecules. The calculated average adsorption energies per H2 for (Ti-nH2 )6 C24 B24 (n = 1–6) are in the energy range from 0.24 to 0.55 eV, which is suitable for hydrogen storage at near-ambient conditions. The Dewar–Kubas interaction dominates the adsorption of H2 on the outer surface of Ti6 C24 B24 . The largest hydrogen gravimetric density of (Ti–6H2 )6 C24 B24 is 8.1 wt%, exceeding the 5.5 wt% by the year 2017 specified by the US department of energy (DOE). Therefore, the stable Ti6 C24 B24 can be applied as one candidate for hydrogen storage materials at near-ambient conditions. Graphical abstract: Total 12 carbon atoms of six equivalent C–C bonds of C60 are removed and 24 carbon atoms in six rings are replaced by boron atoms, generating the C24 B24 cage. Six Ti atoms are located on the hollow site of six B4 rings. The calculated binding energy (Eb ) of Ti6 C24 B24 at the Perdew-Burke-Ernzerhof functional based on the generalized gradient approximation (PBE/GGA) level is 8.58 eV, which is larger than the corresponding experimental metal cohesive energy (6.43 eV at the PBE/GGA method). Therefore, the problem of the Ti atoms aggregative to form cluster is expected to be overcome, and the material will be stable for designing a recyclable hydrogen material. It is known from the consecutive adsorption energy (Er ) that each Ti atom can adsorb 6 hydrogen molecules at absolute zero temperature. The average binding energy per atom (Ead /H2 ) of (Ti-nH2 )6 C24 B24 (n = 1–6) basing on the PBE/GGA method are between 0.24 and 0.55 eV, which is between physisorbed and chemisorbed states, so Ti6 C24 B24 should be a good candidate for reversible hydrogen storage at near-ambient conditions. Highlights: Ti atoms can bind strongly the surface of Ti6 C24 B24 and do not suffer from clustering. Each Ti atom can store six hydrogen molecules with the moderate average adsorption energy per H2 . The (Ti–6H2 )6 C24 B24 can release more H2 molecules at higher temperature.