In situ growth engineering of ultrathin dendritic PdNi nanosheets on nitrogen-doped V ₂ CT _x MXenes for efficient hydrogen evolution

Immobilizing metal nanoparticles on a support is crucial for catalysts' stability and spatial distribution. MXenes are promising substrates for in situ growth engineering of various electrocatalysts owing to their merits. A stronger binding capacity can be achieved between the in situ-fabricated catalysts and MXenes compared to a common physical combination. Thus, synergistically utilizing morphology modulation, composition optimization, and the interfacial interaction between metal catalysts and supports will maximize the electrocatalytic activity. However, most reported in situ-formed catalysts on MXenes result in solid 0D nanoparticles and in situ growth of nanoalloy catalysts on MXenes with a precisely controlled morphology is still lacking. Herein, nanodendritic PdNi alloys are in situ grown on nitrogen-doped V₂CT_x, serving as efficient electrocatalysts toward the hydrogen evolution reaction (HER). Thanks to the synergistic effect of the unique nanodendritic structure of PdNi, the merits of N-TBA-V₂CT_x nanosheets, and the strong metal-support interaction between the PdNi and the N-TBA-V₂CT_x support, the in situ-formed Pd₅₈Ni₄₂/N-TBA-V₂CT_x electrocatalyst shows excellent HER performance with an ultralow overpotential of 44.1 mV to achieve 10 mA cm^-2 and a lowest Tafel slope of 39.4 mV dec^-1, which outperforms Pd₅₈Ni₄₂/TBA-V₂CT_x, Pd₅₈Ni₄₂, and Pd/C. Remarkably, the Pd₅₈Ni₄₂/N-TBA-V₂CT_x catalyst can maintain 92.3% of its initial activity even after 50 h of continuous operation.