Aggregation-Resistant 3D MXene-Based Architecture as Efficient Bifunctional Electrocatalyst for Overall Water Splitting

The MXene combining high conductivity, hydrophilic surface, and wide chemical variety has been recognized as a rapidly rising star on the horizon of two-dimensional (2D) material science. However, strong tendency to intersheet aggregate <i>via</i> van der Waals force represents a major problem limiting the functionalities, processability, and performance of MXene-based material/devices. We report a capillary-forced assembling strategy for processing MXene to hierarchical 3D architecture with geometry-based high resistance to aggregation. Aggregate-resistant properties of 3D MXene not only double the surface area without loss of the intrinsic properties of MXene but also render the characteristics such as kinetics-favorable framework, high robustness, and excellent processability in both solution and solid state. Synergistically coupling the 3D MXene with electrochemically active phases such as metal oxide/phosphides, noble metals, or sulfur yields the hybrid systems with greatly boosted active surface area, charge-transfer kinetics, and mass diffusion rate. Specifically, the CoP-3D MXene hybrids exhibit high electrocatalytic activity toward oxygen and hydrogen evolution in alkaline electrolyte. As a bifunctional electrocatalyst, they exhibit superior cell voltage and durability to combined RuO₂/Pt catalysts for overall water splitting in basic solution, highlighting the great promise of aggregation-resistant 3D MXene in the development of high-performance electrocatalysts

MXene-Based Electrode with Enhanced Pseudocapacitance and Volumetric Capacity for Power-Type and Ultra-Long Life Lithium Storage

Powerful yet thinner lithium-ion batteries (LIBs) are eagerly desired to meet the practical demands of electric vehicles and portable electronic devices. However, the use of soft carbon materials in current electrode design to improve the electrode conductivity and stability does not afford high volumetric capacity due to their low density and capacity for lithium storage. Herein, we report a strategy leveraging the MXene with superior conductivity and density to soft carbon as matrix and additive material for comprehensively enhancing the power capability, lifespan, and volumetric capacity of conversion-type anode. A kinetics favorable 2D nanohybrid with high conductivity, compact density, accumulated pseudocapacitance, and diffusion-controlled behavior is fabricated by coupling Ti₃C₂ MXene with high-density molybdenum carbide for fast lithium storage over 300 cycles with high capacities. By replacing the carbonaceous conductive agent with Ti₃C₂ MXene, the electrodes with better conductivity and dramatically reduced thickens could be further manufactured to achieve 37–40% improvement in capacity retention and ultra-long life of 5500 cycles with extremely slow capacity loss of 0.002% per cycle at high current rates. Ultrahigh volumetric capacity of 2460 mAh cm^–3 could be attained by such MXene-based electrodes, highlighting the great promise of MXene in the development of high-performance LIBs