The Effect of Atomic Ordering Transformation of PtNi Nanoparticles on Alkaline Hydrogen Evolution: Unexpected Superior Activity of the Disordered Phase

Compared to the acidic hydrogen evolution reaction (HER), the sluggish reaction rate in an alkaline electrolyte makes it a priority to develop highly efficient and cost-effective catalysts. Incorporation of Pt with transition metals to form alloy nanocrystals with different structures and atomic distributions has been reported as a promising approach to enhance HER activity and improve Pt utilization. However, whether the structural ordering of the Pt-based bimetallic alloy affects the HER activity still remains unknown. Here, we synthesized PtNi/C nanoparticles through a modified coprecipitation method and obtained their ordered and disordered phases at different annealing temperatures in a reducing atmosphere. It is contrary to our expectation that the disordered PtNi/C exhibited a superior activity toward the HER in alkaline media compared with the ordered PtNi/C. To understand this interesting phenomenon, a systematic study combining X-ray diffraction (XRD), transmission electron microscopy (TEM), X-r...