WSe2 Flakelets on N-Doped Graphene for Accelerating Polysulfide Redox and Regulating Li Plating

The practical application of lithium-sulfur batteries is still limited by the lithium polysulfides (LiPSs) shuttling effect on the S cathode and uncontrollable Li-dendrite growth on the Li anode. Herein, elaborately designed WSe₂ flakelets immobilized on N-doped graphene (WSe₂ /NG) with abundant active sites are employed to be a dual-functional host for satisfying both the S cathode and Li anode synchronously. On the S cathode, the WSe₂ /NG with a strong interaction towards LiPSs can act as a redox accelerator to promote the bidirectional conversion of LiPSs. On the Li anode, the WSe₂ /NG with excellent lithiophilic features can regulate the uniform Li plating/stripping to mitigate the growth of Li dendrite. Taking advantage of these merits, the assembled Li-S full batteries exhibit remarkable rate performance and stable cycling stability even at a higher sulfur loading of 10.5 mg cm^-2 with a negative to positive electrode capacity (N/P) ratio of 1.4 : 1.

In situ albumin-binding and esterase-specifically cleaved BRD4-degrading PROTAC for targeted cancer therapy

Proteolysis-targeting chimeras (PROTACs) have recently been of great interest in cancer therapy. However, the bioavailability of PROTACs is considerably restricted due to their high hydrophobicity, poor cell permeability, and thereby low tumor targeting ability. Herein, esterase-cleavable maleimide linker (ECMal)-conjugated bromodomain 4 (BRD4)-degrading PROTAC (ECMal-PROTAC) is newly synthesized to exploit plasma albumin as an 'innate drug carrier' that can be accumulated in targeted tumor tissues. The BRD4-degrading ECMal-PROTAC is spontaneously bound to albumins via the thiol-maleimide click chemistry and its esterase-specific cleavage of ECMal-PROTAC is characterized in physiological conditions. The albumin-bound ECMal-PROTACs (Alb-ECMal-PROTACs) have an average size of 6.99 ± 1.38 nm, which is similar to that of free albumins without denaturation or aggregation. When Alb-ECMal-PROTACs are treated to 4T1 tumor cells, they are actively endocytosed and reach their highest intracellular level within 12 h. Furthermore, the maleimide linkers of Alb-ECMal-PROTACs are cleaved by the esterase to release free BRD-4 degrading PROTACs and the cell-internalized PROTACs successfully catalyze the selective degradation of BRD4 proteins, resulting in BRD4 deficiency-related apoptosis. When ECMal-PROTACs are intravenously injected into tumor-bearing mice, they exhibit a 16.3-fold higher tumor accumulation than free BRD4-PROTAC, due to the shuttling effect of albumin for tumor targeting. Finally, ECMal-PROTACs show 5.3-fold enhanced antitumor efficacy compared to free BRD4-PROTAC, without provoking any severe systemic toxicity. The expression of Bcl-2 and c-Myc, the downstream oncogenic proteins of BRD4, are also effectively suppressed. In summary, the in situ albumin binding of ECMal-PROTAC is proven as a promising strategy that effectively modulates its pharmacokinetics and therapeutic performance with high applicability to other types of PROTACs.

Bimetallic selenides heterostructure embedded in urchin-like core/shell conductive rhombic dodecahedron as sulfur host for high-energy-density lithium-sulfur battery

Lithium-sulfur (Li-S) batteries, characterized by the exceptional theoretical energy density, have emerged as a highly up-and-coming competitor for next-generation power batteries. However, the notorious shuttle effect of lithium polysulfides (LiPSs) and sluggish redox reaction kinetics, particularly under high S loading and lean electrolyte, significantly impeded the commercialized progress of Li-S batteries. Herein, we rationally designed and synthesized a novel urchin-like core/shell rhombic dodecahedron as a S host for the first time, wherein the nanoparticles of bimetallic selenides (CoSe2/Sb2Se3) heterojunction are uniformly encapsulated within nitrogen-doped carbon layer and spiny-like CNTs (NC-CNTs) (denoted as CoSe2/Sb2Se3@NC-CNT). The well-distributed CoSe2/Sb2Se3 heterostructure endows the carbon frame with excellent adsorptivity, catalyzing and conductivity towards LiPSs, enhancing the redox kinetics. Benefiting from these superior properties, the remarkable electrochemical performances exhibit in Li-S batteries. At a high rate of 2 C, after an ultra-long and stable 1000 cycles, the capacity reaches 818.8 mAh g-1, accompanied by an ultralow decay of 0.021 % per cycle from coin battery. Notably, even under high S loading (10.2 mg cm-2) and limited electrolyte (E/S, 3.47 μL mg-1), it still achieves a high areal capacity of 8.14 mAh cm-2 (specific capacity of 797.8 mAh g-1) after 100 cycles at 0.5 C. More strikingly, for pouch battery, it obtains a specific capacity 600.5 mAh g-1 (2.76 mAh cm-2) after 150 cycles at 1 C. Designing and developing a novel heterostructure is a promising strategy, which can enhance high S utilization and extend long-cycle life for the high-energy-density in Li-S battery.

Theory-guided optimization of central metal for efficient MOFs bidirectional catalysis in lithium-sulfur batteries

The migration and shuttling of polysulfides between electrodes during the charge-discharge process pose a considerable challenge in the practical application of lithium-sulfur (Li-S) batteries. To address this, the development of functional separators represents an accessible and cost-effective approach to mitigate the shuttling effect and enhance the chemical kinetics of Li-S systems. In this study, a series of MOFs were constructed by tuning the central metal and used as separation modification to explore the effect of the metal ions in the MOFs on the catalytic conversion of polysulfides. Among them, Co-BTTC exhibited fast ion transport and efficiently captured polysulfides, which accelerated the redox kinetics in Li-S batteries. Consequently, the Co-BTTC-modified separator in coin battery achieves a high reversible capacity of 786 mAh g-1 at 1C more than 800 cycles and a minimum capacity degradation of 0.033 % per cycle. In addition, the battery also achieves a capacity of 500 mAh g-1 at 5C after 200 cycles, exhibiting commendable cycle stability. These findings highlight the potential of Co-BTTC as a separator modifier to advance the performance and cyclability of Li-S batteries.

rGO@TiO2-x Schottky heterojunction for enhanced bidirectional catalysis in polysulfide conversion

The shuttling and sluggish conversion kinetics of lithium polysulfides (LiPSs) lead to poor cycling performance and low energy efficiency in lithium-sulfur batteries (LSBs). In this work, a hierarchically structured nanocomposite, synthesized through a surfactant-directed hydrothermal growth following dopamine-protected pyrolysis, serves as a bidirectional catalyst for LSBs. This nanocomposite comprises N-doped reduced graphene oxide (rGO) nanosheets anchored with uniformly distributed TiO2-x nanoparticles via interfacial N-Ti and C-Ti bonding, resulting in the formation of abundant 2D/0D Schottky heterojunctions (rGO/TiO2-x). Density functional theory (DFT) calculations and in situ Raman characterizations demonstrate that rGO/TiO2-x effectively inhibits the shuttling of LiPSs with enhanced redox kinetics, achieving high utilization of the sulfur cathode and improving the overall reversibility. A high areal capacity is attained at a high sulfur loading and a low electrolyte/sulfur ratio. The initial specific capacity reaches 1010 mA h g-1 at a current density of 0.2C (1C = 1675 mA g-1), and a retention of 86.4 % is attained over 100 cycles. A light-emitting diode (LED) screen using two LSBs with rGO/TiO2-x demonstrates their high potential for practical applications.