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.