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 via 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.