A NiCoP nanocluster-anchored porous Ti₃C₂T_<i>x</i> monolayer as high performance hydrogen evolution reaction electrocatalysts

Abstract

MXenes have received much attention as promising candidates for noble metal-free hydrogen evolution reaction (HER) electrocatalysts due to their high electrical conductivity, surface hydrophilicity, abundant surface functional groups, and great potential for rational hybridization with other materials. Herein, a novel porous monolayered-Ti₃C₂T_x@NiCoP (P-Ti₃C₂T_x@NiCoP) nanostructure was synthesized with uniform distribution of bimetallic compounds for improved charge transfer capability and electrocatalytic activity. In experiments, H₂O₂-utilized oxidation formed a highly mesoporous structure with a maximized surface area of monolayered MXenes as the support. A subsequent solvothermal process followed by phosphidation enabled successful anchoring of highly HER-active NiCoP nanoclusters onto abundantly exposed terminal edges of the P-Ti₃C₂T_x support. The structural porosity of the P-Ti₃C₂T_x nanoflakes played an important role in creating additional room for embedding catalytically active species while stably imparting high electrical conductivity to accelerate charge transfer to NiCoP nanoclusters. With structural modification and effective hybridization, P-Ti₃C₂T_x@NiCoP showed highly enhanced HER activity with significantly lower overpotentials of 115 and 101 mV at a current density of -10 mA cm^-2 in 0.5 M H₂SO₄ and 1.0 M KOH, respectively, along with showing long-term stability over 60 h. As such, our approach of designing structurally modified-Ti₃C₂T_x and hybridizing with other electrocatalytically active species would function as a solid platform for implementing Ti₃C₂T_x-based hetero-nanostructures to achieve state-of-the-art performance in next-generation energy conversion applications.