Confined growth of ultrasmall Rh nanocrystals on B- and N-codoped hollow carbon spheres for efficient methanol oxidation

Abstract

Direct methanol fuel cells (DMFCs) are widely recognized as an environmentally benign energy-conversion system, while their current development is constrained by the suboptimal performance of conventional precious metal-based anode catalysts. In this work, we present a controllable and robust two-step method to realize the confined growth of ultrasmall Rh nanocrystals on boron- and nitrogen-codoped hollow carbon spheres (Rh/BNHCS) as high-performance anode catalysts for DMFCs. Capitalizing on the distinctive architectural merits, including high specific surface area, plentiful mesoporous channels, rich B and N species, uniform Rh distribution, and exceptional electrical conductivity, the as-derived Rh/BNHCS catalyst exhibits a superior methanol oxidation performance with a large electrochemical active surface area of 113.4 m2 g-1, a high mass activity of 1362.9 mA mg-1, remarkable CO tolerance, and good long-term stability, which delivers decisive competitive advantages over conventional carbon-supported Rh catalysts as well as commercial Pt/carbon black and Pd/carbon black catalysts.