Two-Dimensional SnS Mediates NiFe-LDH-Layered Electrocatalyst toward Boosting OER Activity for Water Splitting.

NiFe-layered double hydroxides (NiFe-LDHs), as promising electrocatalysts, have received significant research attention for hydrogen and oxygen generation through water splitting. However, the slow oxidation kinetics of NiFe-LDH, due to the limited number of active sites and the low conductivity, hinders the improvement of the water-splitting efficiency. Therefore, to overcome the obstacles, two-dimensional (2D) SnS was first explored to tailor the prepared NiFe-LDH via the hydrothermal method. A NiFe-LDH/SnS heterojunction is built, which is observed from the microstructural investigations. SnS incorporation could greatly improve the conductivity of the NiFe-LDH sheets, which was reflected by the reduced charge transfer resistance. Moreover, SnS layers modulated the electronic environment around the active sites, favoring the adsorption of intermediates during the oxygen evolution reaction (OER) process, which was verified by density functional theory calculations. A synergistic effect induced by the NiFe-LDH/SnS heterostructure promoted the OER activities in electrical, electronic, and energetic aspects. Consequently, the as-prepared NiFe-LDH/SnS electrocatalyst greatly improved the electrocatalytic performance, exhibiting 20% and 27% reductions in the overpotential and Tafel slope compared with those of pristine NiFe-LDH, respectively. The results provide a strategy for regulating NiFe-based electrocatalysts by using emerging 2D materials to enhance water-splitting efficiency.

In Situ Synthesis of Ni-BTC Metal-Organic Framework@Graphene Oxide Composites for High-Performance Supercapacitor Electrodes.

In response to serious ecological and environmental problems worldwide, a novel graphene oxide (GO) induction method for the in situ synthesis of GO/metal organic framework (MOF) composites (Ni-BTC@GO) for supercapacitors with excellent performance is presented in this study. For the synthesis of the composites, 1,3,5-benzenetricarboxylic acid (BTC) is used as an organic ligand due to its economic advantages. The optimum amount of GO is determined by a comprehensive analysis of morphological characteristics and electrochemical tests. 3D Ni-BTC@GO composites show a similar spatial structure to that of Ni-BTC, revealing that Ni-BTC could provide an effective framework and avoid GO aggregation. The Ni-BTC@GO composites have a more stable electrolyte-electrode interface and an improved electron transfer route than pristine GO and Ni-BTC. The synergistic effects of GO dispersion and Ni-BTC framework on electrochemical behavior are determined, where Ni-BTC@GO 2 achieves the best performance in energy storage performance. Based on the results, the maximum specific capacitance is 1199 F/g at 1 A/g. Ni-BTC@GO 2 has an excellent cycling stability of 84.47% after 5000 cycles at 10 A/g. Moreover, the assembled asymmetric capacitor exhibits an energy density of 40.89 Wh/kg at 800 W/kg, and it still remains at 24.44 Wh/kg at 7998 W/kg. This material is expected to contribute to the design of excellent GO-based supercapacitor electrodes.

Single-cell transcriptomic atlas reveals distinct immunological responses between COVID-19 vaccine and natural SARS-CoV-2 infection.

To control the ongoing coronavirus disease-2019 (COVID-19) pandemic, CoronaVac (Sinovac), an inactivated vaccine, has been granted emergency use authorization by many countries. However, the underlying mechanisms of the inactivated COVID-19 vaccine-induced immune response remain unclear, and little is known about its features compared to (Severe acute respiratory syndrome coronavirus 2) SARS-CoV-2 infection. Here, we implemented single-cell RNA sequencing (scRNA-seq) to profile longitudinally collected PBMCs (peripheral blood mononuclear cells) in six individuals immunized with CoronaVac and compared these to the profiles of COVID-19 infected patients from a Single Cell Consortium. Both inactivated vaccines and SARS-CoV-2 infection altered the proportion of different immune cell types, caused B cell activation and differentiation, and induced the expression of genes associated with antibody production in the plasma. The inactivated vaccine and SARS-COV-2 infection also caused alterations in peripheral immune activity such as interferon response, inflammatory cytokine expression, innate immune cell apoptosis and migration, effector T cell exhaustion and cytotoxicity, however, the magnitude of change was greater in COVID-19 patients, especially those with severe disease, than in immunized individuals. Further analyses revealed a distinct peripheral immune cell phenotype associated with CoronaVac immunization (HLA class II upregulation and IL21R upregulation in naïve B cells) versus SARS-CoV-2 infection (HLA class II downregulation and IL21R downregulation in naïve B cells from severe disease individuals). There were also differences in the expression of important genes associated with proinflammatory cytokines and thrombosis. In conclusion, this study provides a single-cell atlas of the systemic immune response to CoronaVac immunization and revealed distinct immune responses between inactivated vaccines and SARS-CoV-2 infection.

Anion-triggered melamine based self-assembly and hydrogel.

We found that melamine in its protonated form could be triggered by oxoanions such as NO(3)(-), PO(4)(3-), ATP, and SO(4)(2-) to form superstructures and to gelate a large amount of water molecules, presumably resulting from the electrostatic and hydrogen bonding interactions operating in a synergistic manner; the gelation can be reversibly switched off/on by increasing/decreasing pH or temperature.