Tuantuan Zhou

In this paper, we systematically investigated the influence of fluoride on the morphology and electrochemical property of Co₃O₄ nanostructures for hydrazine detection. The results showed that with the introduction of NH₄F during the synthesis process of Co₃O₄, both Co(CO₃)_0.5(OH)·0.11H₂O and Co(OH)F precursors would be generated. To understand the influence of F on the morphology and electrochemical property of Co₃O₄, three Co₃O₄ nanostructures that were respectively obtained from bare Co(CO₃)_0.5(OH)·0.11H₂O, Co(OH)F and Co(CO₃)_0.5(OH)·0.11H₂O mixtures and bare Co(OH)F were successfully synthesized. The electrochemical tests revealed the sensing performance of prepared Co₃O₄ nanostructures decreased with the increase in the fluoride contents of precursors. The more that dosages of NH₄F were used, the higher crystallinity and smaller specific surface area of Co₃O₄ was gained. Among these three Co₃O₄ nanostructures, the Co₃O₄ that was obtained from bare Co(CO₃)_0.5(OH)·0.11H₂O-based hydrazine sensor displayed the best performances, which exhibited a great sensitivity (32.42 μA·mM⁻¹), a low detection limit (9.7 μΜ), and a wide linear range (0.010–2.380 mM), together with good selectivity, great reproducibility and longtime stability. To the best of our knowledge, it was revealed for the first time that the sensing performance of prepared Co₃O₄ nanostructures decreased with the increase in fluoride contents of precursors.

In this work, we report on a novel sodium dodecyl sulfate (SDS)-assisted magnesium oxide (MgO)-based porous adsorbent synthesized by hydrothermal method for intermediate CO₂ capture. For industrial MgO, its CO₂ adsorption capacity is normally less than 0.06 mmol g⁻¹, with a specific surface area as low as 25.1 m² g⁻¹. Herein, leaf-like MgO nanosheets which exhibited a disordered layer structure were fabricated by the introduction of SDS surfactants and the control of other synthesis parameters. This leaf-like MgO adsorbent showed an excellent CO₂ capacity of 0.96 mmol g⁻¹ at moderate temperatures (~300 °C), which is more than ten times higher than that of the commercial light MgO. This novel mesoporous MgO adsorbent also exhibited high stability during multiple CO₂ adsorption/desorption cycles. The excellent CO₂ capturing performance was believed to be related to its high specific surface area of 321.3 m² g⁻¹ and abundant surface active adsorption sites. This work suggested a new synthesis scheme for MgO based CO₂ adsorbents at intermediate temperatures, providing a competitive candidate for capturing CO₂ from certain sorption enhanced hydrogen production processes.

This research introduces a completely new environmental benign synthesis route for obtaining two kinds of inter-mediate and high temperature CO₂ sorbents, Mg-Al layered double hydroxide (LDH) and Li₄SiO₄, from vermiculite. The mineral vermiculite was leached with acid, from which the obtained SiO2 was used for the synthesis of Li₄SiO₄ and the leaching waste water was used for the synthesis of Mg-Al LDH. Therefore, no waste was produced during the whole process. Both Li₄SiO₄ and Mg-Al LDH sorbents were carefully characterized using XRD, SEM, and BET analyses. The CO₂ capturing performance of these two sorbents was comprehensively evaluated. The influence of the Li/Si ratio, calcination temperature, calcination time, and sorption temperature on the CO₂ sorption capacity of Li₄SiO₄, and the sorption temperature on the CO2 sorption capacity of LDH, were investigated. The optimal leaching acid concentration for vermiculite and the CO₂ sorption/desorption cycling performance of both the Li₄SiO₄ and Mg-Al LDH sorbents were determined. In sum, this demonstrated a unique and environment-friendly scheme for obtaining two CO₂ sorbents from cheap raw materials, and this idea is applicable to the efficient utilization of other minerals.

Expanded multilayered vermiculite (VMT) was successfully used as catalyst support and Ni/VMT synthesized by microwave irradiation assisted synthesis (MIAS) exhibited excellent performance in our previous work. We also developed a two-dimensional porous SiO2 nanomesh (2D VMT-SiO2) by mixed-acid etching of VMT. Compared with three-dimensional (3D) MCM-41, 2D VMT-SiO2 as a catalyst support provided a superior position for implantation of NiO species and the as-obtained catalyst exhibited excellent performance. In this paper, we successfully synthesized a layered double hydroxide (LDH) using the spent liquor after mixed-acid etching of VMT, which mainly contained Mg2+ and Al3+. The as-calcined layered double oxide (LDO) was used as a catalyst support for CO methanation. Compared with Ni/MgAl-LDO, Ni/VMT-LDO had smaller active component particles; therefore, in this study, it exhibited excellent catalytic performance over the whole temperature range of 250–500 °C. Ni/VMT-LDO achieved the best activity with 87.88% CO conversion, 89.97% CH4 selectivity, and 12.47 × 10−2·s−1 turn over frequency (TOF) at 400 °C under a gas hourly space velocity of 20,000 mL/g/h. This study demonstrated that VMT-LDO as a catalyst support provided an efficient way to develop high-performance catalysts for synthetic natural gas (SNG) from syngas.