This paper reports the design of ultrasmall triphenylphosphine-stabilized Pt6 nanoclusters for electrocatalytic hydrogen oxidation reaction in alkaline solution. These nanoclusters exhibit high mass activity and stability, outperforming Pt single atoms and Pt nanoparticle analogues. The enhanced performance is attributed to the triphenylphosphine ligand's bifold effect: tuning the nanocluster structure and shifting the d-band center of Pt atoms for favorable adsorption kinetics. The nanocluster electrocatalyst also shows high CO-tolerance.
