Thermostable carbon-supported subnanometer-sized (<1 nm) Pt clusters for the hydrogen evolution reaction

Abstract

The downsizing of catalysts to the atomic scale or subnanometer size can effectively maximize the atomic utilization and enhance the electrocatalytic activity. Carbon-supported Pt single atoms or sub-nanometer-sized Pt clusters (Pt_c/C) are promising catalysts for the electrocatalytic hydrogen evolution reaction (HER). However, critical challenges remain in the mass production of high-quality Pt_c/C catalysts. Herein, we report a facile synthesis method to achieve highly dispersed and highly dense Pt_cs (average diameter of ∼0.4 nm) on various carbon supports (CSs). A tannic acid (TA) monolayer (TA_i)-functionalized CS surface was achieved through π–π interactions without destroying the conjugated structure of CSs. TA_i aids the adsorption of the Pt_c precursor monolayer on CSs in a facile impregnation process. Notably, the thermally treated TA fragment-stabilized Pt_cs strongly anchored to the carbon surface to form a highly thermostable Pt_c/C catalyst, reported here for the first time. The synthesized Pt_c/C catalyst (Pt_c(250)/C) exhibits an exceptionally high Pt mass activity (i_mPt)/turnover frequency (TOF) at η = 60 mV (154.5 A mg⁻¹/156.1 s⁻¹), which are ∼106 times higher than those of commercial Pt/C (1.46 A mg⁻¹/1.48 s⁻¹) and superior to those of the state-of-the-art Pt-based catalysts.