Photo-Energized MoS2/CNT Cathode for High-Performance Li-CO2 Batteries in a Wide-Temperature Range

Li-CO2 batteries are considered promising energy storage systems in extreme environments such as Mars; however, severe performance degradation will occur at a subzero temperature owning to the sluggish reaction kinetics. Herein, a photo-energized strategy adopting sustainable solar energy in wide working temperature range Li-CO2 battery was achieved with a binder-free MoS2/carbon nanotube (CNT) photo-electrode as cathode. The unique layered structure and excellent photoelectric properties of MoS2 facilitate the abundant generation and rapid transfer of photo-excited carriers, which accelerate the CO2 reduction and Li2CO3 decomposition upon illumination. The illuminated battery at room temperature exhibited high discharge voltage of 2.95 V and mitigated charge voltage of 3.27 V, attaining superior energy efficiency of 90.2% and excellent cycling stability of over 120 cycles. Even at an extremely low temperature of - 30 °C, the battery with same electrolyte can still deliver a small polarization of 0.45 V by the photoelectric and photothermal synergistic mechanism of MoS2/CNT cathode. This work demonstrates the promising potential of the photo-energized wide working temperature range Li-CO2 battery in addressing the obstacle of charge overpotential and energy efficiency.

Au Catalyst-Modified MoS2 Monolayer as a Highly Effective Adsorbent for SO2F2 Gas: A DFT Study

To ensure the stable operation of gas-insulated equipment, removal of SF₆ decomposition products of sulfur hexafluoride (SF₆) is one of the best methods. SO₂F₂ is one of the typical decomposition products of SF₆, while the Au-modified MoS₂ (Au-MoS₂) monolayer is a novel gas adsorbent. Therefore, based on the first-principles calculation, the adsorption properties of the SO₂F₂ molecule on the Au-MoS₂ monolayer are calculated. Furthermore, the adsorption energy, charge transfer, and structure parameters were analyzed to obtain the most stable adsorption structure. These results indicate that all of the adsorption processes are exothermic. To better study the adsorption mechanism between the SO₂F₂ molecule and the Au-MoS₂ monolayer, the density of states, the highest occupied molecular orbital, the lowest unoccupied molecular orbital, and electron density difference were obtained. At last, we conclude that the interaction between the SO₂F₂ molecule and the Au-MoS₂ monolayer was chemisorption. This study provides a theoretical basis to prepare the Au-MoS₂ monolayer for the removal of SF₆ decomposition products.

The Modulation Effect of MoS₂ Monolayers on the Nucleation and Growth of Pd Clusters: First-Principles Study

The geometries, electronic structures, adsorption, diffusion, and nucleation behaviors of Pdn (n = 1⁻5) clusters on MoS₂ monolayers (MLs) were investigated using first principles calculations to elucidate the initial growth of metal on MoS₂. The results demonstrate that Pd clusters can chemically adsorb on MoS₂ MLs forming strong Pd⁻S covalent bonds with significant ionic character. We investigated the initial growth mode of Pd clusters on MoS₂ monolayers and found that Pdn clusters tend to adopt pyramid-like structures for n = 4⁻5 and planar structures lying on MoS₂ substrates for n = 1⁻3. It can be explained by the competition between adsorbate⁻substrate and the intra-clusters' interactions with the increasing coverage. Compared with pristine MoS₂ MLs, the work function was reduced from 5.01 eV upon adsorption of Pd monomer to 4.38 eV for the case of the Pd₅ clusters due to the charge transfer from Pd clusters to MoS₂ MLs. In addition, our calculations of the nucleation and diffusion behaviors of Pd clusters on MoS₂ MLs predicted that Pd is likely to agglomerate to metal nanotemplates on MoS₂ MLs during the epitaxial stacking process. These findings may provide useful guidance to extend the potential technological applications of MoS₂, including catalysts and production of metal thin films, and the fabrication of nanoelectronic devices.

An efficient cluster model to describe the oxygen reduction reaction activity of metal catalysts: a combined theoretical and experimental study

An efficient model containing only 7 metal atoms was proposed to describe the ORR activity of metal catalysts by DFT calculation.