Ultrasmall Pd nanocrystals confined into Co-based metal organic framework-decorated MXene nanoarchitectures for efficient methanol electrooxidation

The natural scarcity and insufficient utilization of noble metal-based catalysts bring a heavy block in the way of the widespread applications of direct methanol fuel cells. Herein, we propose a feasible bottom-up approach to the construction of ultrasmall Pd nanocrystals confined into Co-based metal organic framework-decorated Ti3C2Tx MXene (Pd/MOF-MX) nanoarchitectures via a controllable solvothermal process. The ultrathin MXene nanolamellas and porous Co-based MOFs constitute an ideal hybrid carrier with high electron conductivity and large accessible surface areas, which not only facilitates the size restriction and uniform dispersion of Pd nanocrystals, but also ameliorates their intrinsic catalytic activity through the direct electronic interactions. By virtue of the pronounced synergistic coupling effects, the newly-developed Pd/MOF-MX nanoarchitectures exhibit markedly enhanced electrocatalytic properties towards the methanol oxidation reaction, including a large electrochemically active surface area of 116.7 m2 g−1, a high mass activity of 1700.4 mA mg−1 as well as a satisfactory long-term durability, which are superior to those of traditional Pd electrocatalysts anchored on carbon blacks, carbon nanotubes, graphene, and undecorated MXene matrixes.