Synergistic charge transfer and proton enrichment in Pt/PDDA-modified CNTs for enhanced hydrogen evolution reaction

Abstract

Herein, Pt nanoparticles/poly dimethyl diallyl ammonium chloride (PDDA) modified carbon nanotubes (CNTs) were synthesized through reduction by ethylene glycol (EG), denoted as EG-Pt/pCNTs. At a Pt loading of 2.31 wt%, EG-Pt/pCNTs were found to exhibit significant electrochemical hydrogen evolution reaction (HER) performance with a Tafel slope of 137 mV dec⁻¹ and 35 mV dec⁻¹ in alkaline and acid solutions, respectively. As control experiments, X-ray photoelectron spectroscopy (XPS) and Raman spectra showed that electrons can be transferred from PDDA to Pt atoms, which was more favorable for adsorbing H* species. Density functional theory (DFT) calculations further confirmed intermolecular charge transfer and charge rearrangement for the Pt atoms. In addition, the experimental results demonstrated that EG-Pt/pCNTs exhibited a strong capacity for proton enrichment. Ultimately, the HER kinetics dramatically improved for EG-Pt/pCNTs. This strategy can be used to transform inert CNTs into highly efficient HER electrocatalysts with low noble metal loading.