Carbon nanotube-bridged MXene nanoarchitectures decorated with ultrasmall Rh nanoparticles for efficient methanol oxidation

Rational design and precise synthesis of cost-effective and highly-active Pt-alternative anode catalysts are important paths to accelerate the application and promotion of direct methanol fuel cell. Herein, a robust and controllable synthetic strategy is developed to the bottom-up construction of carbon nanotube-bridged Ti₃C₂T_x MXene nanoarchitectures decorated with ultrasmall Rh nanoparticles (Rh/CNT-MX) through a facile co-assembly process. The existence of MXene nanosheets with abundant anchoring sites can immobilize nanosized Rh crystals and facilitate their dispersion, while the integration of CNT skeletons effectively separates the neighboring MXene layers and offers unimpeded electron transport channels, which are conducive to making full use of respective catalytic functions for each component. As a consequence, the optimized Rh/CNT-MX catalyst expresses superior methanol oxidation performance with a considerable electrochemically active surface area of 89.4 m² g^-1, high mass/specific activity of 911.0 mA mg^-1/1.02 mA cm^-2, and reliable long-term durability, which has obvious competitive advantages over the conventional Rh/carbon black, Rh/CNT, Rh/MXene as well as commercial Pt/carbon black and Pd/carbon black catalysts.