Laminar MoS2 Nanosheets Embedded into Organosilica Membranes for Efficient H2 Separation

Abstract

Two-dimensional (2D) molybdenum disulfide (MoS2) with a unique action on H2 was incorporated into 1,2-bis(triethoxysilyl)ethane (BTESE)-derived bridged microporous organosilica networks to form a composite membrane for H2 separation by a sol–gel method. Due to their opposite ζ-potentials, a continuous surface without lamellar boundary defects was formed between BTESE sols derived by the hydrolysis–polymerization reaction and MoS2 nanosheets. When the MoS2 content increased in BTESE networks, the H2 permeance showed an overall increasing trend in the range of 1.85–2.89 × 10–7 mol·m–2 s–1 Pa–1 (552–864 GPU), which was higher than that of pristine BTESE membrane with the H2 permeance of 491 GPU. In addition, optimized MoS2/BTESE membranes showed a much higher H2/N2 permselectivity of 129 than that of the pristine BTESE membrane of 17 at 100 °C. The synergistic effect of BTESE and MoS2 nanosheets plays an important role. Through adsorption isotherm test and diffusivity as well as energy calculation, BTESE networks became denser by nonporous MoS2 addition that prevented N2 from passing, while H2 was promoted with excellent adsorption on charged edges of MoS2, resulting in improved H2 separation performance both in permeance and selectivity. This provides an attractive mechanism for hydrogen separation.