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The adsorption behavior and mechanism of H 4 Ti 5 O 12 (1 1 0) and H 4 Ti 5 O 12 (1 1 1) were systematically investigated by experiments and theory calculations, which indicates H 4 Ti 5 O 12 (1 1 1) has more potential on Li+ recovery. [Display omitted] • The H 4 Ti 5 O 12 with (1 1 0) and (1 1 1) facets exposed were synthesized. • The adsorption uptake of H 4 Ti 5 O 12 (1 1 1) is higher than that by H 4 Ti 5 O 12 (1 1 0). • The adsorption of [Li(H 2 O) 4 ]+ on H 4 Ti 5 O 12 (1 1 1) is more stable than (1 1 0). • Li+ is easier diffused from (1 1 1) facet into Li 4 Ti 5 O 12 crystal than (1 1 0) facet. The improved adsorption capacities by increasing specific surface area methods are merely reached about 50% of H 4 Ti 5 O 12 's theoretical adsorption capacity, and the adsorption behavior and mechanism of lithium on special facets of H 4 Ti 5 O 12 remain unclear. In this study, a flower-shaped Li 4 Ti 5 O 12 and an octahedral Li 4 Ti 5 O 12 were prepared with the specific surface areas of 176.23 and 83.02 m2/g, and the corresponding adsorption behaviors of the obtained adsorbents exposed with (1 1 0) and (1 1 1) facets were investigated by using experimental and computational methods. The maximum Li+ uptake values on H 4 Ti 5 O 12 (1 1 0) and H 4 Ti 5 O 12 (1 1 1) are 26.85 mg/g and 33.56 mg/g at 45 °C in 24 mM LiCl solutions, respectively. The fifth reuse ability of H 4 Ti 5 O 12 (1 1 1) still remains 88.9% of the original's, which is higher than H 4 Ti 5 O 12 (1 1 0) (76.3%). Although with lower specific surface area, the octahedral H 4 Ti 5 O 12 have higher ions selectivity, greater adsorption capacity, and better reuse ability than flower-shaped H 4 Ti 5 O 12 , which may due to the special (1 1 1) facet exposed. Firstly, H 4 Ti 5 O 12 (1 1 1) owned small hole sizes can inhibit other ions diffusing into H 4 Ti 5 O 12 and improve the ion selectivity. Secondly, the immigration paths by the First-principles calculations revealed that the Li+ migrate onto the Li 4 Ti 5 O 12 (1 1 1) is easier to than Li 4 Ti 5 O 12 (1 1 0) through 8a-16c-8a-16c sites. At last, [Li(H 2 O) 4 ]+ can form the stable complexes and its adsorption energies on (1 1 1) are higher than on (1 1 0) facets, which may lead to larger adsorption capacity and better reuse ability. This work will help to understand the [Li(H 2 O) 4 ]+ adsorption behavior and mechanism on different crystal facets by experiments and computations. [ABSTRACT FROM AUTHOR]

[Display omitted] • H 3 LiTi 5 O 12 (HTO) nanoparticles with high Li+ selectivity were synthesized. • HTO-AC based cathode was used to electro-sorb Li+ from both simulated and raw brine. • Electricity can enhance the Li+ adsorption kinetics and capacity by HTO. • Li+ adsorption energy on HTO surface was analyzed by DFT calculation. The rapid consumption of lithium ion (Li+) battery for electronic devices has significantly increased the demand for lithium resource in recent years. The salt-lake brine is considered as the ideal source for Li+ extraction, but the co-existing cations, such as Na+ and K+ limit its recovery efficiency when the adsorption method is applied. In this study, the H 3 LiTi 5 O 12 nanoparticles (HTO) with a spinel structure were synthesized as Li+-selective adsorbent. The static adsorption experiments showed that the Li+ absorption capacity of HTO was significantly affected by the pH of bulk solution, and exhibited a high separation factor of Li+/Na+ and Li+/K+ at 37 and 16, respectively. When HTO was mixed with activated carbon (AC) and coated on the cathode plate, the Li+ adsorption kinetics (rate constant) was significantly enhanced from 0.18 to 0.25, due to the accelerated rate of the film diffusion driven by the electric field. Density functional theory (DFT) calculation result showed that applying electricity can strengthen the hydrogen bond between Li and O atom on the HTO (1 1 1) facet. When the AC mixing ratio was increased from 10% to 50%, the Li+ desorption efficiency increased from 47% to 90%, but at the expense of sacrificing the adsorption capacity, which decreased from 18.1 mg/g to 9.8 mg/g. In terms of the overall recovery efficiency of Li from brine, the weight ratio of HTO:AC at 9:1 was suggested for the electro-sorption method. Finally, the Li+ recovery from actual brine was successfully demonstrated, with 7.1 mg/g of adsorption capacity and well stability. [ABSTRACT FROM AUTHOR]