A nanocatalyst with an interface between Pt and NiSx on carbon black (PtNiSx/CB) was synthesized, exhibiting superior electrocatalytic activities toward the oxygen reduction reaction (ORR) and 5-hydroxymethylfurfural (HMF) oxidation reaction. Based on bifunctional PtNiSx/CB, a new type of direct HMF fuel cell was assembled, which can continuously convert HMF to value-added 2,5-furandicarboxylic acid with stable discharging performance.