Few-layer tellurium : cathodic exfoliation and doping for collaborative hydrogen evolution

Abstract

2D tellurium is a suitable electrocatalyst support that can assist electron transport while hosting active sites, yet its production remains challenging. Herein, a cathodic exfoliation method that can exfoliate Te crystal directly to Te nanosheets at low potential, also enabling simultaneous transition metal doping on Te nanosheet surface is presented. In situ Raman spectra and ex situ characterizations reveal that the cathodic exfoliation relies on the electrostatic repulsion between Te flakes covered with in situ generated ditelluride (Te22−) anions. The Te22− anions can anchor metal ions to the surface, and the doping concentration can be tuned by adjusting the concentration of metal ion in the electrolyte. The metal-doped Te nanosheets exhibit highly improved hydrogen evolution activities. In particular, Pt-doped Te outperforms polycrystalline Pt at high overpotential. A collaborative hydrogen production mechanism via Volmer–Heyrovsky pathway is suggested: Te22− adsorbs protons and assists the mass transfer to adjacent Pt atoms where the protons are reduced and released as hydrogen.